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IJCST 13,1
Progress towards effective garment CAD D.X. Gong, B.K. Hinds and J. McCartney
12 Received June 1998 Revised June 2000 Accepted June 2000
School of Mechanical and Manufacturing Engineering, The Queen's University of Belfast, Belfast, UK Keywords Drape, Fabric, Garments, Fabric drape Abstract The requirements in CAD modelling of garments are first considered and alternative user interfaces are considered. Features which occur in block patterns and for which accurate simulation is required are identified. An energy based modeller, developed for drape simulation, is introduced and applied to model garment constructional details in fabric test specimens of variable stiffness. The modeller is further applied to garment pieces in contact with a mannequin to compare drape with and without constructional features.
Introduction The use of computers to model and visualise garments has been a topic for development over the past few years. Early systems simply used the computer as a medium to provide 2D sketches, but the realism of the images could be greatly enhanced by adding fabric textures, obtained from scans or textile CAD systems. The further ability to warp textures and to substitute textures on primary photographic images also improved the appearance of synthesised images. The task of modelling a garment as a 3D geometric entity is much more difficult. There are fundamental problems associated with the curvature complexity of garment surfaces and the fact that the shape assumed by the garment is usually determined as the response of the garment assembly to the underlying form to which it has been applied. This contrasts with 3D CAD applied in the mechanical engineering and other sectors, where the geometry information is dictated by the designer and remains invariant after definition, except perhaps in those circumstances where off-line structural analysis indicates that dimensions should be changed. Effective CAD based on 3D modelling should predict accurately the shape taken by a garment on a body form. Designers might reasonably expect a realistic indication of appearance and feedback based on fabric material characteristics. The question of the type of user interface in relation to the precise inputs and outputs is still an unresolved issue and it is possible to envisage alternative scenarios. Figure 1 shows the most obvious and simple case where a CAD system is used to provide a visualisation of how predefined or existing block patterns would appear when applied as an assembly to a body form.
International Journal of Clothing Science and Technology, Vol. 13 No. 1, 2001, pp. 12-22. # MCB University Press, 0955-6222
This work is sponsored by EPSRC grant REF. GR/L 35638. The first author was supported by a visiting studentship from the Queen's University of Belfast and an ORS awarded from the CVCP. The help of those involved is gratefully acknowledged. Delaunay triangulations involved in the paper were produced by a Delaunay Triangulator provided by Jonathan R. Shewchuk in Carnegie Mellon University, to whom the authors would like to offer their thanks.
Progress towards effective garment CAD 13
Figure 1. Scenario one for 3D garment design
An alternative approach is shown in Figure 2 in which the garment pieces are defined by the user during the design cycle. This procedure is used in the footwear industry but the problem in the present context is the developability of the panels as prescribed. In the footwear industry, a 2D pattern can usually
Figure 2. Scenario two for 3D garment design
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be determined for the equivalent 3D piece due to the stretch capability of the shoe upper material. However, in certain circumstances the shapes defined as garment pieces by the designer would require the insertion of darts and occasionally gussets in order to realise the 3D shape, even with some contribution from material deformation. The concept in Figure 2 is more attractive in that it offers the capability of creating new designs from scratch. This paper recognises the importance of accurate drape simulation in the context of a complete garment CAD system. Typical circumstances which would have to be modelled are identified in existing block patterns. A fabric deformation model based on energy minimisation is introduced below and is used to model particular garment features. In this respect, the present work goes beyond the drape simulation of simple cases reported in the literature and addresses the particular circumstances which arise with fitting procedures in garment construction, namely darts and the assembly of pieces with dissimilar edges. The contribution of fabric properties is considered and the important link between the level of discretisation and simulation detail is considered. First, a short review of previous relevant work is presented. Relevant previous work Drape modelling There is currently a great deal of interest in drape modelling. A recent comprehensive review has been presented by Ng and Grimsdale (1996). Three approaches are identified for modelling fabric deformation. These have been named as the geometrical, physical and hybrid approaches. The group referred to as physical models is the most relevant for accurate CAD simulation of fabric deformation, being based on parameters which reflect the deformational characteristics which distinguish one fabric from another. Two approaches are used. Energy-based techniques (Feynam, 1986; Breen et al., 1994; Okabe et al., 1992) regard a piece of fabric as having an energy sum, made up of potential energy and internal strain energy. The positions of points of the fabric are allowed to relax until there is equilibrium between the potential energy and the internal strain energy. An alternative approach uses force-based techniques (Terzopoulos, et al., 1987; Chen and Govindaraj, 1995; Aono, 1990). Modelling the fabric as a mesh of points of finite mass on a rectangular or triangular grid, the forces between the points are represented in differential equations of motion. Integration on time steps gives the dynamic positions of the fabric. Ng and Grimsdale (1996) comment that the energy-based methods are used to produce static simulations while force-based techniques are used in dynamic simulations or animation. Modelling with 3D CAD While there is significant interest in modelling fabric, there has been relatively less interest in the problems of incorporating fabric deformation methods within CAD systems or in addressing the situations which occur in garment construction.
Okabe et al. (1992) present details of an energy-based modeller incorporated Progress in a 3D CAD system. Examples of simulated garments, associated with paper towards effective patterns, are shown on a mannequin. The Asahi Apparel CAD 3D-PDS system garment CAD (Niki, 1995) is also a 3D system which allows designers to model patterns which incorporate a fabric stiffness parameter. Both these systems accept the mechanical properties of fabrics as measured by KES, the Kawabata 15 measurement system. However, it is important to appreciate that the garment construction method also has an important influence on the shape taken by the garment. Hu et al. (1997) have examined the effect of seams on fabric drape. They conclude that seam position, type, structure, direction and testing method all contribute to the draped shape. On this basis, it is imperative that 3D garment modelling can handle the level of detail that is required when making decisions on the acceptability of designs. The next section considers patterns for a simple garment and identifies particular features which drape simulation would have to deal with. Consideration of assembly of garment pieces Figure 3 shows the block patterns for a lady's T shirt. Essentially some primary 3D shape is incorporated in the finished garment by introducing darts and dissimilar adjoining edges on separate pieces. For example, the dart at AA0 will enforce a conical shape around the breast area. The assembly of B to B0 and C to C0 introduce curvature changes which give much better fit to the sleeve to shoulder areas of the garment. In modelling terms it becomes necessary to simulate the effect on fabric deformation and appearance caused by these features. The dart AA0 has approximately equal sides which are drawn together. The assemblies of BB0 and CC0 require the drawing together of edges which are of different curvatures and perhaps of different lengths. Also the
Figure 3. Block patterns for a simple lady's T shirt
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edge seam of D and D0 forms a waist shape which is normal for ladies garments. In addition, seams will introduce additional weight and stiffness which will also contribute to the final shape taken.
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Energy-based fabric deformation model In order to explain the modelling problems of garment constructions, an energy based modeller with the following attributes was developed. A piece of fabric is considered to have energy components due to gravity, tension, shear and bending. Each energy component is represented by a term in the energy equation: Etotal Egravitational Etensile Eshear Ebending :
1
Etotal is the total energy of the fabric; Egravitational is the potential energy; Etensile is the tensile or compressive energy component due to extension or compression of weft and warp yarns; Eshear is the shear energy between warp and weft yarns, and Ebending is the energy component due to the yarn bending. The model can deal with garment panels of arbitrary shape, modelled as a set of triangular facets in 3D space. A Delaunay triangulation or similar scheme can be used to equalise triangle size and avoid extreme triangle shapes. The direction of the grain line can be taken into account by defining warp and weft directions. Details of the energy model are now considered in more detail. Gravitational energy The gravitational energy is the sum of potential energy of all triangles. For each triangle this is given by Eg A g h0 ;
2
where, is the mass per unit area, A is the area of an original triangle, g is the gravitational acceleration, and h0 is the height of the centroid of the current triangle. Tensile and shear strain energy The sum of the tensile strain energy and the shear strain energy represents the total internal energy of all triangles. Consider a single triangle in the fabric defined in a u; v frame prior to deformation (Figure 4). Under deformation, the 2D triangle form undergoes an affine transformation to its 3D shape. Moving a vertex of a triangle causes a shape change which relates to an energy change in the model. Note that triangle rotation and translation do not change the internal tensile and shear energies of a triangle, but scaling and shear do. The scaling factors Su ; Sv and shear angles 'u ; 'v in two orthogonal directions associated with the change from the original triangle to the deformed triangle determine the internal tensile and shear energies. The scaling factors Su ; Sv and shear angles 'u ; 'v can be calculated from the affine transformation (Wolberg, 1990).
Progress towards effective garment CAD 17
Figure 4. 2D and 3D triangle
The tensile strain energy of a triangle along two directions is: ZZ ZZ 1 1 2 Es Ksu
Su ÿ 1 dudv Ksv
Sv ÿ 12 dudv 2 2
3
o 1 n A Ksu
Su ÿ 12 Ksv
Sv ÿ 12 ; 2 where, Ksu A is the area of the original triangle. Ksv are the tensile constants for the weft and warp directions. The shear energy of a triangle is given by: ZZ 1 1 1 Er
4
Kr '2u Kr '2v dudv A
Kr '2u Kr '2v 2 2 2
where Kr is the shear modulus. The total of the tensile strain energy Etensile and the shear energy Eshear of the fabric is the sum of the tensile strain energy and the shear energies of all triangles. Bending energy Bending energy exists between two neighbouring triangles that share one edge but are not in the same plane. The bending energy along one edge is given as 1 Eb Kb l
ÿ 2 : 2
5
l is the length of the edge; and is the angle between two planes of two triangles, i.e. the angle of two normals to the triangles. The total bending energy Ebending is the sum of the bending energy of all edges except for the edges that are on the boundaries.
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Relaxation method The total energy of the fabric is calculated as the sum of the above four energies of which the independent variables are the geometric positions of all nodes, i.e. the three co-ordinates in 3-D space. The relaxation model operates on points in the grid and modifies their positions to minimise the energy. The Fletcher-Reeves-Polak-Ribiere method (FRPR) and the Broyden-Fletcher-Goldfarb-Shanno (BFGS) minimisation are often recommended. The BFGS requires somewhat more intermediate storage than the FRPR routine, but it works well with a globally convergent strategy that requires only approximate line minimisation, and can therefore be more efficient (Vetterling et al., 1992). The BFGS optimisation method is employed in the present model. The modeller is written in C and runs on a Silicon Graphics O2 with a R5000 processor. Application of modeller for garment construction In order to assess the problems of modelling darts and other features, the modeller was used to simulate two cases in rectangular test pieces ± a simple dart with equal length straight sides and a more complex dart, again with straight edges but having unequal lengths. In both cases, the test piece is suspended from two corners positioned at the same height but closer together than the edge length. The results for the first case are shown in Plate 1. Plate 1(a) shows the triangulation of the test piece and Plate 1(b), (c) and (d) are simulation images associated with increasing values of bending stiffness. The characteristics 1:5 10ÿ5 kg/mm2, Ksu Ksv 10:0N/mm, Kr 10:0N/mm were used in the three simulations, but increasing bending stiffness Kb 0:01N in (b), Kb 0:1N in (c) and Kb 1:0N in (d) is tested. A dense triangulation was adopted around the edges of the dart and assembly is applied by forcing nodes on one side of the dart to adopt the same position as corresponding nodes on the other side. No additional stiffness associated with seams or stitching was specified in these simulations but if suitable experimental values were available the model could be readily updated. The overall shape taken by the fabric is dependent on the presence of the dart which would be expected to impose a conical shape. In the less stiff fabric model, substantial buckling of the fabric occurs due to the weight and asymmetry of the piece. The transition to a stiffer fabric reduces the buckling and the predominant conical shape emerges. Plate 2 considers the case of a dart with dissimilar lengths of sides. The same number of nodes occur on each side of the dart but are obviously more closely spaced on the shorter side. Again, Plate 2(b) and (c) are simulations with increasing bending stiffness. The assembly of unequal lengths causes compression on one side of the dart and stretch on the other side. The effect of the increase in bending stiffness causes a transition from frequent minor buckling to fewer, larger wavelength buckles which carry across the dart line.
Progress towards effective garment CAD 19
Plate 1. Simulation of a rectangular test piece with a simple dart associated with increasing values of bending stiffness
An important aspect of the model is the interaction between the fabric stiffness, the triangle density and the number of wavelengths. If a user expects to be warned of puckering or minor wrinkles, it is necessary that the triangulation is capable of demonstrating the occurrence of the wrinkles by having a sufficiently high density of triangles to approximate the shape locally. With heavier, stiffer fabrics, the wrinkles may not be inclined to occur and a lower triangulation density would be sufficient.
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Plate 2. Simulation of a test piece having a dart with dissimilar length of sides associated with increasing values of stiffness
Modelling of darts in a front body panel To extend the modelling of darts to drapes against a body form, a comparative test was carried out. The drape simulation now has to consider the presence of the body. This is conventionally done by adding a repulsion force when a node of the fabric comes close to the body surface so as to prevent breakthrough. In the present case, a body panel without darts is compared with a panel which includes darts, a dart to a sleeve edge and a waist suppression dart together with some straightening of edges. In both cases, the garment pieces are anchored to the body form at particular corner points A, B, C and D. The results are shown in Plate 3, together with the triangulations used in the simulations.
Progress towards effective garment CAD 21
Plate 3. Modelling of the front body panels without and with darts
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A reduced density of triangles around the darts is adopted compared with the previous case as no minor wrinkles along the darts are expected. Also, since no additional seam stiffness is included, a sharp edge across the dart at the waist is suggested by the simulation. Comparison between the two cases shows wrinkles occurring down the front edge of the plane pattern together with a fold running from the breast point. In overall terms, the inclusion of the darts gives a better fit and a smoother overall appearance. Concluding remarks The work described here represents an initial attempt to provide garment designers with authentic predictions of garment shape modelling within a CAD environment. Future work will concentrate on modelling garment piece assemblies which include traditional fitting devices such as darts and seams. Additional garment features such as padding and linings must also be considered. The relationship between the density of triangulation, bending stiffness and the detail expected in simulations is an issue which requires further investigation. Modelling detailed deformations is possible but at a greater computational cost. The simulations in Plate 1 and 2 took typically around 8 minutes on the Silicon Graphics O2 platform, but since these were only features which might be included in a whole garment simulation, it is possible that adaptive meshing techniques could be applied to tune mesh density to material characteristics and localised areas of variable curvature. References Aono, M. (1990), ``A wrinkle propagation model for cloth'', Proceedings of Computer Graphics International'90, Springer, Tokyo, pp. 96-115. Breen, D.E., House, D.H. and Wozny M.J. (1994), ``Predicting the drape of woven cloth using interacting particles'', SIGGRAPH'94, Computer Graphics Proceedings, Annual Conference Series, pp. 365-72. Chen, B. and Govindaraj, M. (1995), ``A physically based model of fabric drape using flexible shell theory'', Textile Res. J., Vol. 65 No. 6, pp. 324-30. Feynman, C.R. (1986), ``Modelling the appearance of cloth'', MSc thesis, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, MA, Cambridge. Hu, J., Chung, S. and Lo, M. (1997), ``Effect of seams on fabric drape'', International Journal of Clothing Science and Technology, Vol. 9 No. 3, pp. 220-27. Ng, H.N. and Grimsdale, R.L. (1996), ``Computer graphics techniques for modelling cloth'', IEEE Computer Graphics and Applications, Vol. 16 No. 5, pp. 28-41. Niki, T.C. (1995), ``The Asahi Apparel CAD 3D-PDS system, one of the many exciting new exhibits at Bobbin'95'', CAD Developments, Apparel International, December, pp. 35-7. Okabe, H., Imaoka, H., Tomiha, T. and Niwaya, H. (1992), ``Three dimensional apparel CAD system'', Computer Graphics, Vol. 26 No. 2, pp. 105-10. Terzopoulos, D., Platt, J.C., Barr, H. and Fleischer, K. (1987), ``Elastically deformable models'', Proceedings of SIGGRAPH'87, Computer Graphics, Vol. 21 No. 4, pp. 205-14. Vetterling, W.T., Teukolsky, S.A., Press, W.H. and Flannery, B.P. (1992), Numerical Recipes, Example Book [C], 2nd ed., Cambridge University, Cambridge, pp. 168-84. Wolberg, G. (1990), Digital Image Warping, IEEE Computer Society Press, London, pp. 45-51.
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Drape formation based on geometric constraints and its application to skirt modelling Xiaoqun Dai, Takao Furukawa, Shigeru Mitsui, Masayuki Takatera and Yoshio Shimizu
Drape formation
23
Faculty of Textile Science and Technology, Shinshu University, Japan Keywords Modelling, Drape, Particle, Clothing Abstract Drape is a characteristic behaviour of flexible cloth, so it is important in modelling cloth. The paper introduces a novel method to model drape using a few shape parameters, predicted according to the pattern structure and mechanical properties of cloth. The technique is used to visualize the 3-D drapeability of cloth and is then extended to simulation of a skirt. The general shape of a flared skirt of large deformation is predicted based on several shape parameters. Moreover, the constructed skirt model is used as pre-draped initial shape for the popular physically-based model ± particle system. Kawabata Evaluation System (KES) plots of cloth are applied for accurate mechanical calculation. The simulated results show good agreement with actual cloth materials.
1 Introduction As cloth modelling is increasingly important for textiles and apparel CAD/CAM, character animation, electronic commerce and related areas, it has attracted considerable attention in computer graphics as well as in textile manufacturing. The computer graphics community has been driven by a desire to include realistic, physically-based cloth objects in images and animations. As they are more interested in visual appearance than in the precise simulation of texture, most of their work has focused on developing computationally tractable models that produce cloth-like behaviour. The textile community has focused more on describing the complex mechanics inherent in cloth. In their early research, variation in cloth behaviours was related to traditional mechanical parameters: Young's modulus, bending modulus and Poisson's ratio. More recently, the Kawabata Evaluation System (KES) for woven fabrics was developed to measure cloth mechanical properties (Kawabata, 1980). This community aims to introduce such mechanical properties to cloth modelling. Drape, as a typical behaviour of flexible cloth that influences its aesthetic appearance, has drawn much attention from the textile community. Drape ability has been regarded as a quantitative characteristic of cloth, and several devices as well as virtual systems have been developed to measure it (Booth, 1968; Jeong, 1998; Stylios and Wan, 1999). Furthermore, research predicting cloth drape according to its mechanical properties has also been This work was supported by the Ministry of Education, Sciences, Sports and Culture of Japan under a Grant-in-Aid for COE Research (No. 10CE2003).
International Journal of Clothing Science and Technology, Vol. 13 No. 1, 2001, pp. 23-37. # MCB University Press, 0955-6222
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carried out (Akiyama, 1997; Yang and Matsudaira, 1998; Zhang and Matsudaira, 1998). Integration of the above two groups' work has been expected to advance the technology and application of cloth modelling. Inspired by this, we propose a geometrical method to model cloth drape, using a few shape parameters predicted according to the pattern structure and mechanical properties of cloth. This method is first used to visualize the 3-D drapeability of cloth, and is then extended to flared skirt modelling. The skirt drape model constructed is then used as a pre-draped initial shape for further mechanical calculation, and skirts made of different materials are visualized. 2 Related work 2.1 Cloth modelling Cloth drape was initially visualized by Weil's geometrical techniques (Weil, 1986), where hanging cloth is represented as a point-grid, and the shape is derived by fitting catenary curves. This model was extended by Taillefer (1991) to reflect more complicated factors, including stretching, bending, gravitational and self-repulsion energies, but it is still unable to represent complex cloth deformation. The finite element method (FEM) is a popular technique to analyse deformation of an elastic continuum, and has been introduced into cloth modelling (Collier et al., 1991; Eischen et al., 1996). Imaoka et al. (1989; 1992) used FEM to predict 3-D drape shape of a skirt from its 2-D paper pattern. Although FEM gives a clear mathematical description of elastic objects, it is insufficient to describe complex boundary conditions in cloth simulation. Moreover, it requires excessive amounts of memory to store the stiffness matrix describing the basic relationship among elements. On the other hand, as cloth is a composite material composed of warp and weft rather than a continuous sheet, discrete models describing cloth behaviour with spring-mass or particle models have been proposed. Based on these models, Eberhardt et al. (1996) simulated the dynamic drape of tablecloths, and Thalmann (Carignan et al., 1992; Thalmann, 1998) introduced an approach to simulate the dynamic appearance of clothing on virtual actors. However, these models are insufficient to reflect the complicated mechanical properties of actual cloths. Breen et al. (1994) first described a clear non-linear relationship between measured mechanical properties of cloth and the particle system. KES bending and shearing plots were used to obtain the internal forces acting within cloth. Their simulated tablecloth showed obvious effects of different materials, while over-stretching of cloth remained a problem. Sakaguchi et al. (1994; 1998) are also developing a dressing-simulation system based on the spring-mass model, focusing on the dependency of the cloth materials, although they have not attained a clear correspondence with the mechanical properties of cloth. Stylios and Wan (1999) have also proposed a lumped-parameter model, visualizing
drape measurement by modelling cloth property parameters. Their simulation Drape formation shows general consistency with real measurements. However, the computational cost is not clear. 2.2 Drape evaluation The most widely accepted method of drape test uses the so-called Drapemeter (Booth, 1968). In this test, a circular cloth sample whose diameter is 10in. is placed on a disk with a diameter of 5in. The cloth drapes and compresses internally owing to gravity, finally resulting in a flared shape (see Figure 1). The cross-section appears as a smooth wavy curve, usually described as the hemline. Then the drape coefficient, described as the ratio of the vertical projection area to the entire sample area, is used to evaluate cloth drapeability. However, the drape coefficient alone is not sufficient to characterize cloth drapeability. The number of folds formed by a drape sample (node number) has also been used to describe cloth drapeability. To investigate the relationship between the drape shape and cloth mechanical properties, Yang and Matsudaira (1998) have proposed a geometric model based on a trigonometric function for the hemline formed by a drape test sample. Although the preservation of cloth area has not been considered and the simulation has not shown very close results to actual samples, the empirical formula obtained, shown as equation (1), does help to predict node number. Moreover, the drape-distance ratio, illustrated in Figure 1, has been proposed as an alternative to drape coefficient by Jeong (1998). Jeong made a device to measure cloth drapeability, and investigated the relationship between the ratio and cloth mechanical properties.
25
Figure 1. Definition of the drape distance ratio
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B n 12:797ÿ5:775 W
13 1 B G 2HG
2 0:373 ÿ 0:015 0:129
1 W W W
n: node number; W : cloth weight[g/cm2 ]; B: bending rigidity[gf cm2 /cm]; G: shearing rigidity[gf/deg./cm]; 2HG: shearing hysteresis [gf/cm].
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However, both node number and drape-distance ratio are abstract parameters, and are insufficient to describe cloth drape. Stylios et al. (1999) have proposed a new concept of virtual measurement ± 3-D fabric drapeability, which is to visualize the 3-D drape of a cloth sample using cloth mechanical properties. This can provide a basis for drape evaluation aesthetically and mechanically, and is helpful in textile and fashion design. 3 Drape formation Even though the behaviour of draped cloth involves complex stretching, bending and shearing deformations, the bending deformation is remarkably large while the stretching and shearing deformations are small. As a result, the length and area of cloth are roughly preserved even when the cloth shape changes greatly. The preservation of length and area are regarded as geometric constraints in cloth drape. 3.1 Node number prediction The samples used for the drape test were thick cotton, thin cotton and thin wool. In Table I, the characteristic parameters involved in equation (1) were obtained from KES measurement and the node numbers were predicted by using equation (1). In a real drape test, the thick cotton sample often results in four or five nodes; the thin cotton sample often results in five nodes, but sometimes appears as six nodes. This is consistent with the formula in equation (1). On the other hand, since the correlation coefficient of this formula is reported as 0.85 (Yang and Matsudaira, 1998), consistency for the wool sample is inadequate. The thin wool sample often results in seven or eight nodes. The pictures in the left two Table I. Characteristic parameters and node numbers of cloth samples
Sample Thick cotton (No. 1) Thin cotton (No. 2) Thin wool (No. 3)
W
B
G
2HG
n
0.0156 0.01134 0.01344
0.13 0.05 0.03
1.04 1.34 0.3
1.76 2.4 0.19
4.51 5.08 6.23
columns of Figure 2 show the test results. The figures in the right two columns Drape formation show the respective simulations using a drape formation technique to be explained. 3.2 Hemline modelling based on buckling curve In Figure 3(a), line AB represents an elastic bar. When the end A is fixed and a load P is imposed at the end B, the bar bends while its length
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Figure 2. Drape test and its simulation
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Figure 3. Hemline modelling
is approximately preserved. Curve AB shows the natural bent shape and is named a buckling curve. The bending moment at a point
x; y due to P is M ÿPy EI =r (where EI is the flexural rigidity of the bar and r the radius of curvature). Solving this equation, we can obtain equations in equation (2) describing this curve. Here, h, p and k are its shape parameters, and E
p; and F
p; are the first and second elliptic integrals, respectively (details have been given by Frisch-Fray, 1962). Since the bending of a bar is
similar to hemline deformation, the buckling curve is adopted to construct a Drape formation hemline. 8 1 > > x 2E
p; ÿ F
p; ; > > > k > > > < y 2p cos =k:
2 s F
p; =k > > 29 > > > p sin sin
=2 > > > : k 2p=h 8 2 > > XC 2E
p ÿ K
p > > k > > > > 1 > > ÿ 2E
p; C ÿ F
p; C ; > < k
3 YC 2p cos
ÿ C =k > > > > > 2 1 > > LC K
p ÿ F
p; C > > k k > > : p sin C sin
=2 R XC = tan ÿ YC :
4
To describe a nodal unit, curve BC, which is a part of the symmetric curve of AB in relation to point B, is jointed to curve AB (refer to Figure 3(a)); and AC is also adjoined to its mirror symmetric curve across the Y axis. The equations in equation (3) give the coordinates of point C and the length of AC. Let C 0 be the symmetric point of C in curve AB. Here, E
p and K
p are the first and second complete elliptic integrals, respectively. When the angle shown in Figure 3(a)) equals =n and LC equals L=2n, n such nodal units can be arranged on a circle with C 1 continuity and form a closed hemline of length L, as shown in Figure 3(b). The circle constitutes a basis for the hemline and equation (4) gives its radius (R). With the node number (n), the hemline length (L) and the radius (R) given, the shape parameters (p; k) can be solved from equations (3) and (4). By using equation (2), curve AC is obtained and then a hemline is determined uniquely. A drape specimen can be represented as a series of concentric circles from its centre to its edge. We refer to distance along the circumference of a circle as latitudinal length, and the radial distance between two near circles as longitudinal length. When the specimen is draped over a drape meter disk, the circles, other than those supported by the disk, form a series of curves referred to as hemlines. Three such hemlines are shown in Figure 3(c). From inside to outside, L increases from 2rd to 2rf while R increases from rd to rad , as illustrated in Figure 1. n can be predicted by equation (1), and rad is expected to be predicted according to Jeong's work. However, here we use n and rad resulting from real tests. The 3-D Z coordinates of these hemlines are calculated
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to keep the longitudinal length constant. During the transformation from 2-D hemlines to 3-D ones (Figure 3(d)), L may change slightly. When the length change is large, it can be adjusted. As a result, the longitudinal and latitudinal length of the cloth sample as well as its area are preserved approximately during the drape formation.
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3.3 Hemline transformation The hemline shown in Figure 3(d) is close to that formed by a cloth of good drapeability, such as the thin wool shown in Figure 2. However, the samples of thin cotton and thick cotton do not result in such full and regular nodes (see Figure 2), in part because of rigidity, anisotropy, and the initial state of the material. A specimen of high bending or shearing rigidity which results in n nodes often forms a curve similar to an n-gon in the centre, even though it is supported by the drapemeter disk. The respective hemlines also seem to lie on similar n-gonal curves consisting of lines and arcs rather than circles. Our approach here is to construct such curves and fit the circular hemlines to them with length preservation. For instance, we construct a hexagonal curve for the hemline of six nodes. First, obtain the circumscribed hexagon of the drape meter disk and replace the corners with tangent arcs. The length of each of the remaining line segments depends on the mechanical properties of the cloth. The higher the rigidity of the cloth, the longer these segments are. The precise relationship between these quantities will be found by a large number of drape test experiments. However, for this example, we determined the length by trial and error. The dashed line in Figure 4(d) is the constructed hexagonal curve. In geometry, a curve can be approximated by equation (5) when it is sampled with steps of length l=cn (l is its length and cn is the number of segments), as shown in Figure 4(a). Here, i corresponds to its curvature. To transform the curve while preserving its length, only a change of the angle i is required. 8 j i X X > l > > x x cos m > 0 > < i c m0 j0 n
5 j i > X X > l > > sin m > : yi y0 c m0 j0 n
i 1; 2; ; cn " 8 # j i X X > L 2 > > X X0 cos m ÿ m > > < i c cn m0 j0 n " # j i > X X > L 2 > > sin m ÿ m > : Yi Y0 c cn m0 j0 n
i 1; 2; ; cn :
6
Drape formation
31
Figure 4. Hemline transformation
If we sample the base circle in Figure 4(b) and the hexagonal curve in Figure 4(d) with the same number of segments (cn ), then i denotes the curvature of the hexagonal curve, while the curvature of the circle is a constant (2=cn ). Let the circumferences of both curves be l; by regarding m in equation (5) as 2=cn ÿ 2=cn m , the circle is developed into a straight line shown in Figure 4(c), and is then reconstructed into the hexagonal curve with length preservation by equation (5). Then sample the circular hemline with steps of L=cn and let i denote its curvature. Similarly, by equation (6), the hemline is developed as shown in Figure 4(c) and is then transformed into that shown in Figure 4(d) with its length preserved (more details can be found in Dai et al. (1998). By this procedure, the results shown in the right two columns in Figure 2 are obtained. In the top views in Figure 2, the horizontal direction is along the warp, while the vertical direction is along the weft. The two kinds of cotton specimens seem to have more difficulty bending in the warp direction than in the weft direction and show obvious anisotropy; the thin wool specimens form more regular nodes and show good drapeability. Although both kinds of cotton specimens form five nodes, their drape shapes differ from each other due to
IJCST 13,1
32
their different mechanical properties. The respective simulations are consistent with the actual tests. These figures confirm that the hemline model based on the buckling curve is feasible to describe 3-D cloth drape. 4 Skirt simulation Cloth drapeability has important effects on clothing shape, especially dresses and skirts. Here we focus on a flared skirt, an item of clothing that forms free drapes as a whole, and is popular for its beautiful and even folds. When worn on the body, the shape of the skirt at the waist and hip where folds do not appear is dealt with as tight clothing, and this part is described simply using the surface shape of the underlying body. Away from the hipline, the skirt shape mainly depends on the cloth's own drapeability, so that the proposed drape model is used to simulate it. 4.1 Shape parameter of a flared skirt In Section 3, a drape model described by several drape parameters has been proposed. To extend it to simulation of a skirt, shape parameters for the skirt are necessary. The relationship between the shape of a flared skirt and the mechanical parameters of cloth has been investigated (Akiyama, 1997; Zhang and Matsudaira, 1998). The proposed parameters used to describe a flared skirt are summarized as follows: . Node number. . Spreading angle: angle included by the bottom hemline and side line. . Average node size: the average width and amplitude of the node units. As mentioned above, cloth length and area are considered as constants although the skirt behaves with large drape deformation. For a skirt put on a human body, if its node number and spreading angle are given, the width and amplitude of its nodal units are roughly determined based on geometric constraints. Therefore, the general shape of the flared skirt can be described by the node number and the spreading angle, which are expected to be predicted according to the pattern structure and mechanical properties of the cloth. In this instance, we made a flared skirt as shown in Figure 6(a) with the thin cotton material. It is called an escargot skirt since its paper patterns are of spiral shape, and the seaming lines are not symmetric. The node number is 12, and the spreading angle is 81 degrees. Simulation is then carried out using these parameters and the pattern size. 4.2 Skirt modelling When a skirt is placed on a human body, its hemline depends on the shape of the body hipline. Here, we use an approach to constitute hemlines lying on the base curves of a shape similar to the hipline shown in Figure 5(b). With the skirt hemline circumference (L), node number (n), and radius of the base circle (R) (the circumference of which equals that of the hipline) given, a circular
Drape formation
33
Figure 5. Skirt hemline modelling
hemline is constructed as shown in Figure 5(a). By the method mentioned in Section 3.3, it is then transformed into that shown in Figure 5(b). A skirt model is then formed by a series of hemlines from the hipline to the bottom of the skirt. Here, the circumferences (L) of hemlines are obtained from the actual skirt, and the radii (R) of the base circles for hemlines from top to bottom are increased gradually to satisfy the condition that the spreading angle equals 81 degrees. The Z coordinates of hemlines are calculated to keep the longitudinal length of the skirt constant. Figure 6(b) shows the simulated skirt placed on a woman's body, and it is similar to the real one shown in Figure 6(a). 4.3 Validation with particle system In Section 4.2, the general shape of a flared skirt is obtained under geometric constraints. However, the real shape of the skirt is far more complicated. It results from the balance of stretching, bending and shearing forces acting within the cloth, as well as its gravity. To obtain the skirt shape that reflects the concrete mechanical properties of cloth, mechanical calculation is necessary. Here, the particle model proposed by Breen et al. (1994) is adopted. Woven cloth, which is a composite material constructed by warp and weft threads, differs from a continuous sheet. Therefore, it can be represented by a particle system in which each intersection corresponds to a particle, and cloth springs are imagined acting on the yarn segments between crossing-point particles to simulate the mechanical behaviour of cloth (refer to Figure 7). The force acting on a particle located at the position
i; j in a lattice at time t, and its equation of motion are summarized in equation (7). ( t Fij mij x tij cx_ tij :
7 Ftij Ftstretchij Ftbendij Ftshearij mij g; tij denote the velocity Here, xtij denotes the 3-D position of the particle, x_ tij and x and acceleration of the particle, respectively; while mij and c represent the mass
IJCST 13,1
34
Figure 6. Flared skirts
Figure 7. Particle system
of the particle and viscosity resistance, respectively. Spring forces Fbendij and Fshearij are extracted according to KES bending and shearing plots, basically as described by House (1998). To solve the over-stretching problem in Breen's
model, a KES stretching plot is used for calculating Fstretchij . We solve equation Drape formation (7) by the predictor-corrector method (an improved Euler method). Further details have been given by Mitsui et al. (2000). In Figure 8, the upper figures are side views and the lower ones are upward views. Figure 8(a) is the pre-draped skirt model obtained above, used as the initial state for the particle system; (b) and (c) are the results after mechanical 35 calculation using KES plots of the thin cotton and thin wool, respectively. Here, ÿ4 approximately 20,000 iterations with t 10 sec are required for convergence of the calculation. The nodes of the initial geometric model (Figure 8(a)) show unstable slender shapes; as shown in Figure 8(b), after the mechanical calculation using the KES data for thin cotton, they come to take more natural and physically stable shapes which are closer to those of the actual skirt (Figure 6(a)). However, the deformation is not great, and the comparison between Figures 8(a) and (b) confirms that the geometrical model has provided a shape quite close to that of the skirt in this case. There is a little irregular deformation in the escargot skirt (see Figure 8(a)) because of the high rigidity at the seaming lines. Since the seaming lines are not modelled in the particle system, the simulation could not reflect such effects. Figure 8(c) shows regular and full nodes that are consistent with the drape test results shown in the lower two rows in Figure 2 due to the good drapeability of thin wool. Cloth does not stretch significantly when it is simply draped under its own gravity, and the simulation results show agreement with it.
Figure 8. Skirt simulation based on particle model
IJCST 13,1
36
5 Conclusion We have proposed a drape formation method based on geometrical constraints, from which a drape model is constructed reflecting the mechanical properties of cloth. It is used to visualize the 3-D drapeability of cloth, as well as the general 3-D shape of a skirt. Comparison with a real drape test and an actual skirt confirmed that the drape model is feasible. Moreover, the skirt model worked as an initial state for further mechanical calculation, and its physically stable shape was reached. The simulation results demonstrate that the skirt model shows good consistency with the mechanical properties of cloth. The proposed method is expected to be used in textile and fashion design, apparel manufacture, and related areas. While the geometric method enables us to simulate cloth drapes simply and quickly, the details, such as effects of cloth anisotropy and seaming lines, are difficult to reflect well, even using the modified hemline model. In skirt simulation, even though our approach has provided an initial pre-draped 3-D model to the particle system, the high computational cost still remains a problem to be solved. These problems will be resolved in the future. References Akiyama, T. (1997), ``Silhouette shapes of flared skirts ± part 2: effect of hem length and fabric properties on shape of hemline'', Journal of Textile Machinery Society of Japan, Vol. 50 No. 2, pp. 91-8. Booth, J.E.(1968), Principles of Textile Testing, 3rd ed., Heywood, London. Breen, D.E., House, D.H. and Wozny, M.J. (1994), ``A particle-based model for simulating the draping behavior of woven cloth'', Textile Res. J., Vol. 64 No. 11, November, pp. 663-85. Carignan, M., Yang, Y., Thalmann, N.M. and Thalmann, D. (1992), ``Dressing animated synthetic actors with complex deformable clothes'', Proc. SIGGRAPH '92, July, pp. 99-104. Collier, J.R., Collier, B.J., O'Toole, G. and Sargand, S.M. (1991), ``Drape prediction by means of finite-element analysis'', J. Text. Inst., Vol. 82 No. 1, pp. 96-107. Dai, X., Furukawa, T., Takatera, M., Hanazato, T. and Shimizu, Y. (1998), ``Dress modelling based on paper pattern and its application to interactive apparel design and manufacture'', Proc. VSMM '98, November, pp. 102-7. Eberhardt, B., Weber, A. and Strasser, W. (1996), ``A fast, flexible, particle-system model for cloth draping'', IEEE, Computer Graphics and Applications, Vol. 16 No. 5, September, pp. 52-9. Eischen, J.W., Deng, S. and Clapp, T.G. (1996), ``Finite-element modelling and control of flexible fabric parts'', IEEE, Computer Graphics and Applications, Vol. 16 No. 5, pp. 71-80. Frisch-Fray, R. (1962), Flexible Bars, Butterworths, London, pp. 6-11. House, D.H. (1998), ``Cloth and clothing in computer graphics'', Course Notes SIGGRAPH '98, pp. B1-B17. Imaoka, H., Okabe, H., Tomiha, T., Yamada, M., Akami, H., Shibuya, A. and Aisaka, N. (1989), ``Prediction of three-dimensional shapes of garments from two-dimensional paper patterns'', SEN-I GAKKAISHI, Vol. 45 No. 10, pp. 60-6. Jeong, Y.J. (1996), ``A study of fabric-drape behaviour with image analysis'', J. Text. Inst., Vol. 89 No. 1, pp. 70-9. Kawabata, S. (1980), The Standardization and Analysis of Hand Evaluation, The Textile Machinery Society of Japan.
Mitsui, S., Komai, D., Dai, X., Furukawa, T., Takatera, M., Shimizu, Y. and Hashimoto, M. (2000), ``Particle model reflecting non-linearity and anisotropy of cloth mechanical properties and its collision and repulsion model'', Journal of the Institute of Image Information and Television Engineers, Vol. 54 No. 12. Okabe, H., Imaoka, H., Tomiha, T. and Niwaya, H. (1992), ``Three-dimensional apparel CAD system'', Computer Graphics, Vol. 26 No. 2, pp. 105-10. Sakaguchi, Y. and Harada, T.(1998), ``PARTY: virtual reality and dressing environment'', Journal of Textile Machinery Society of Japan, Vol. 49 No. 7, pp. 360-8. Sakaguchi, Y., Minoh, M. and Ikeda, K. (1994), ``PARTY: a numerical calculation method for a dynamically deformable cloth model'', Trans. IEICE (D-II), Vol. J77-D-II No. 5, pp. 912-21. Stylios, G. and Wan, T. (1999), ``The concept of virtual measurement 3D fabric drapeability'', International Journal of Clothing Science and Technology, Vol. 11 No. 1, pp. 10-18. Taillefer, F. (1991), ``Mixed modelling'', Proc. Compugraphics, pp. 467-78. Thalmann, N.M. (1998), ``Clothing virtual actors'', Course Notes SIGGRAPH '98, pp. D-1-D-26. Weil, J. (1986), ``The synthesis of cloth objects'', Proc. SIGGRAPH '86, August, pp. 49-54. Yang, M. and Matsudaira, M. (1998), ``Measurement of drape coefficients of fabrics and description of hanging shape of fabrics'', Journal of the Textile Machinery Society of Japan, Vol. 51 No. 9, pp. 68-77. Zhang, R.M. and Matsudaira, M. (1998), ``Analysis of flared skirt's silhouette'', Journal of the Textile Machinery Society of Japan, Vol. 51 No. 11, pp. 60-6.
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The current issue and full text archive of this journal is available at http://www.emerald-library.com/ft
IJCST 13,1
Geometrical modelling of garments Yves Chiricota
38 Received April 2000 Accepted November 2000
Universite du QueÂbec aÁ Chicoutimi, Chicoutimi, QueÂbec, Canada, and
Olivier Cochaux and Andre Provost
PAD System Technologies, MontreÂal, QueÂbec, Canada Keywords Garments, Apparel, Modelling, Clothing Abstract This paper describes a method for fast three-dimensional approximation of clothing from flat patterns. The pictures obtained are closely related to technical sketches used in the apparel industry. Our approach was implemented in a CAD program as currently used in the industry. Based on the parameterisation of flat polygonal curves and measurements, a geometrical approximation of the garment is achieved by reshaping the surfaces, using some curves as stating points. The methods herein described were applied to model certain elements inherent to the field of clothing design, such as collars, lapels and waistbands.
International Journal of Clothing Science and Technology, Vol. 13 No. 1, 2001, pp. 38-52. # MCB University Press, 0955-6222
Introduction Three-dimensional modelling of clothing was first envisioned within the context of computer animation. A paper by Weil (1986), in which a geometrical algorithm for computer generated images of fabric is described, figures among the earliest references on the subject. Later, Terzopoulos et al. (1987) introduced physical fabric simulation methods based on the elasticity theory. Carignan et al. (1992), Lafleur et al. (1991), and Volino et al. (1996) also worked along those lines. Also, Breen et al. (1994; 1996) presented a simulation method based on the minimisation of the energy function of a system of particles that model fabric. Other research looks to optimise the processing time of simulation data. Among them figures Provot (1995), who proposes a geometrical method based on the masses-springs system. From another perspective, Witkin et al. (1998) introduced an algorithm based on implicit integration, which significantly reduces simulation time. Finally, Desbrun et al. (1999) describe a predictioncorrection type integration algorithm that facilitates virtual environment simulations. The modelling problem is also approached from the angle of apparel CAD systems, which relies on the apparel industry. This has led to the development of a few systems. Work by Hinds et al. (1990) deals with a three-dimensional clothing design system, which makes flat patterns from virtual models. Okabe et al. (1992) developed a design system that can toggle between flat patterns and three-dimensional models. For their part, Stylios et al. (1996) presented a system adapted to virtual reality. More recently, Kang et al. (2000a; 2000b) developed a system for drape shape prediction, using finite element analysis method. A survey covering major approaches to modelling can be found in Hardaker and Fozzard (1998) and Ng and Grimsdale (1996). Of importance here is the fact that the production of clothing is subject to constraints that are not
found in computer animation. Modelling in an industrial context requires greater technical realism (close attention to pattern details). Described herein is a geometrical modelling algorithm that has been implemented in CAD software, as used in the apparel industry. This algorithm can produce a three-dimensional geometrical approximation of a garment in a few seconds, based on a flat pattern. This representation makes it possible for the designer to verify his design (collar position, waistband details, etc). The images obtained resemble the technical sketches used as illustrations by pattern designers. Our approach means that the greater part of the virtual assembly process of a garment, from a flat pattern, is automated. We have noticed that pattern makers often lack the technical skills to utilise complex design software. The methods we have developed improve on the user-friendly aspect of this type of software. The user works entirely from a window in which the flat pattern is presented. The algorithm herein described is made up of three parts. First, the polygons used to represent the pattern are measured. Second, a three-dimensional frame made up of spline curves that represent the garment, from 2-D measurements, is constructed. These curves are then used to form the Coons surfaces, which then serve as the initial conditions for a physical simulation. In the pages that follow, we will focus on the modelling of bodices; similar techniques have been used for skirts and trousers. The user interface and the data to be entered for the modelling simulation are described thereafter. The methods for measurement and parametrisation of polygons are presented in the following section. The last section deals with three-dimensional reconstruction methods. These methods are based on an automatic modelling algorithm for spline curves. A few examples of garments modelled by our system are shown in the Appendix. User input Patterns are presented as flat polygonal curves called ``pieces''. They appear in a window and the user is required to mark a number of specific points on the pattern, called ``reference points'', and then supply assembly instructions. Moreover, the pattern can include darts, which will be considered in the calculations for the three-dimensional model. A method that takes darts into account during a physical simulation will be described in the last section. Figure 1 identifies the reference points and assembly details required to model a bodice. The pattern is placed horizontally before the algorithm is applied. The algorithm is designed to consider each type of garment (bodice, skirt, trouser) from the polygonal curves, the generic shape of which is predetermined. Each curve is called ``fragment''. Figure 2 identifies the fragments used to model a bodice. The numbers in the polygons are the indexes that identify the fragments. When a pattern is made up of many pieces assembled together, a flat assembly is first performed, in which the extremities of the
Geometric modelling of garments 39
IJCST 13,1
40
Figure 1. Information required to model a bodice
Figure 2. Bodice fragments
pieces are joined by bending the contours of the polygons, whenever it is necessary. In this way, the fragments required for modelling the garment are obtained. When the reference points and assembly details have been added to the pattern, the rest of the procedure is automated. The first step of the calculations consists in measuring the fragments. This procedure will be discussed in the next section. Measurement method The Euclidean plane will be indicated by E2 , and the three-dimensional Euclidean space by E3 . The elements of E2 and E3 are points. Polygonal curves Let us first establish a few notations. If we consider P and Q, two points on the plane, the segment that links points P and Q will be denoted by
PQ. The length of a segment is defined by `
P; Q jP ÿ Qj. The notation
P; will be used to designate the point obtained by the orthogonal projection of point P on the line, as determined by segment .
Consider L
P0 ; P1 ; . . . ; Pn ; a list of points on the plane. The closed curve c
P0 ; P1 ; :::; Pn associated with these points is defined as being the list of segments:
P0 ; P1 ;
P1 ; P2 ; . . . ;
Pn ; P0 : In the same manner, an open curve is defined by the list of segments:
P0 ; P1 ;
P1 ; P2 ; . . . ;
Pnÿ1 ; Pn :
Geometric modelling of garments 41
When there is no possibility of confusion, c will be used to designate curve c
P0 ; P1 ; . . . ; Pn . So defined, the curves are evidently provided with a direction. The notation 2 c will be used to indicate that segment belongs to the list of segments defining c. In what follows, it is assumed that if c is a curve then 1 ; 2 2 c, and 1 6 2 ) 1 \ 2 1. The length P of a curve c will be noted as `
c. It is defined in an evident way by `
c 2c `
. Let us say that a point P belongs to a curve c, denoted P 2 c, if a segment of the curve includes that point. Given a simple curve c, and two points, P and Q, on that curve, the curve obtained by following c clockwise from point P to point Q will be denoted as ÿ
P; Q; c. When curve c is implicit, it will be written as ÿPQ . Consider C0 as the first point on curve c, and L `
c. A point on the curve of which the distance (measured by following the segments according to their orientation) to C0 is uL, will be denoted by c
u, (u 2 0; 1). Seen thus, curve c is a function, c:
0; 1 ! E2 , of which the range is defined by segments
Ci ; Ci1 . Measuring the fragments Let us now take a look at how the fragments are measured. In what follows, reference points will be identified as A, B; . . . ; F. To retrace how the points have been renamed, just compare Figures 1 and 3. Let us assume that the fragments are aligned in such a way that the line defined by points E and F is parallel to the horizontal axis. For each fragment, three points (X, Y and Z ) are calculated initially from reference points (A, B; . . . ; F), as illustrated in Figure 3. These points are added to the listÿof fragment reference points. They are calculated thus: X ÿAB
109 , Y ÿBC 23 and Z
X;
E; F. Three segments are then defined, 1 , 2 ,
Figure 3. Additional points
IJCST 13,1
42
Figure 4. Cutting up into subfragments
Figure 5. Exterior curves
and 3 , using the following formulae: 1
X; Z , 2
Y ;
Y ; 1 , and 3
Y ; E. These segments partition the fragment into four connected areas. The simple polygonal curves found at the borders of these areas are called ``sub-fragments'' (see Figure 4(b)). The four sub-fragments of a bodice fragment are called tubular, chest, underarm, and shoulder sub-fragments. Consider a flat surface of which the fragment is the frontier. One will notice that it is possible to bend this surface simultaneously along segments 2 and 3 , without tearing it. One of the main qualities of the algorithm is the ability to predict the result of curving the four fragments along these axes, in such a way as to fold the surfaces on themselves. The sub-curves of the fragments that correspond to the edge of the surface resulting from this operation are called ``exterior-curves''. These are defined based on the position of the reference points in the fragment. Figure 5 shows the exterior curves of a bodice fragment. Curve ÿBC is called armhole curve, and curve ÿDE is for called collar curve. The measurement of a fragment comprises two steps. First, for each subfragment, segments called ``measurement segments'' are created from the reference points. The position of the measurement segments is predetermined for each sub-fragment. In the second step, the segments are used to calculate a parametrisation of the exterior curves. This parametrisation is achieved by projecting sample points from the exterior curves onto the measurement segments. We will use a shoulder sub-fragment to illustrate the measurement method. The measurement segments defined for the shoulder sub-fragment are 1
R1 ; C where R1
C;
Y ; E, and 2
R2 ; D where R2
D;
Y ; E (see Figure 6(a)). The type of projection used to calculate the parametrisation of sample points depends on the configuration of segments
C; D and
E; Y . Initially, let us suppose that segments
C; D and
E; Y are not parallel, as shown in Figure 6(b). Consider a point W 2 ÿYC for which we wish to calculate the parametrisation. Consider U
E; Y \
C; D. The
Geometric modelling of garments 43 Figure 6. Measure of the shoulder sub-fragment
parametrisation of point W is derived through perspective projection in relation to the centre U of that point on segments 1 and 2 . To this end, consider Qi i \
U ; W (i 1; 2). The parameters of point W are defined by the triplet
l1 ; l2 ; h, where li jRi ÿ Qi j
i 1; 2 and h jQ1 ÿ W j. When segments
Y ; E and
C; D are parallel, orthogonal projection of point W can be applied to the measurement segments. We will describe how the position of point W in E3 is calculated from the triplet
l1 ; l2 ; h in the next section. Over and above the sampling of exterior curves, certain additional parameters are calculated, such as angle 1 (respectively 2 ) defined as the angle between segment 1 (respectively 2 ), and the horizontal axis (the bodice being aligned along that axis). Tubular sub-fragments are measured differently from the three other types of sub-fragments. It is important to note that these sub-fragments correspond to the cylindrical part (torso) of the bodice. The measurement segments used for this sub-fragment correspond, overall, to the intersection ÿ of a vertical tube and a horizontal plane. More precisely, consider Vi ÿAX ni (i 0; . . . ; n) and 0 Vi
Vi ;
F; Z . The sub-fragment is measured using couples
i ; hi , 0 0 where hi jF ÿ Vi j and i
Vi ; Vi . This parametrisation is illustrated in Figure 6(c). The whole of this information is finally entered into a database. They are thereafter used to create the three-dimensional geometrical model. Construction of the three-dimensional model This section discusses how a garment is put together in three dimensions, based on two-dimensional measurements. Automatic modelling of curves Modelling a garment from measurements relies on a method for automatic adjustment of curves derived by means of control points. This method allows modelling a curve by displacing control points so as to arrive at a given length.
IJCST 13,1
44
The method will be applied to BeÂzier curves. The method can be applied to any type of curve defined by control points. Given a list of control points
P0 ; P1 ; . . . Pn (where Pi 2 E3 ), the BeÂzier curve (of degree n) associated to these points is defined by: n X
P0 ; P1 ; . . . ; Pn ; t Bni
tPi ; i0
ÿ where u 2 0; 1 and Bni
t ni
1 ÿ tnÿi ti are the Berstien polynomials of degree n
0 i n. The curve will be referred to as
t when the control points are understood. Points
P0 ; P1 ; . . . Pn define a convex polyhedron denoted as
P0 ; P1 ; . . . ; Pn , which we refer to as ``control polyhedron''. The length of the BeÂzier curve, referred to as `
is defined by R1 `
0 j 0
tjdt. The three-dimensional vector space will be denoted by R3 . Given a list of points
P0 ; P1 ; . . . Pn , a function :
E3 n1 Rÿ!E3 , called ``displacement function'', is defined by: k
P0 ; P1 ; . . . ; Pn ; u Pk uVk
P0 ; P1 ; . . . ; Pn ; where u 2 R; u 0 and Vk :
E3 n1 ÿ!R3 is a function which calculates a fixed vector that depends on points Pi . Let us denote the half-line with origin Pk and direction Vk by k . The function k calculates, for each value u, a point belonging to k . In particular, if u 0, we have k
u Pk . In what follows k
u will be used when points P0 , P1 ; . . . ; Pn are understood. A modelling function is a function :
E3 n1 Rÿ!
E3 n1 defined by:
u
P0 ; P1 ; . . . ; Pn ; u
0
u; 1
u; . . . ; n
u; where each k
u
k
P0 ; P1 ; . . . ; Pn ; u) is a displacement function. For each value of parameter u, function calculates a vector
Q0 ; Q1 ; . . . ; Qn containing n 1 control points Qk k
u
k 0; 1; . . . ; n). In particular, if u 0;
u
P0 ; P1 ; . . . ; Pn . The vector calculated by function defines a BeÂzier curve
Q0 ; Q1 ; . . . ; Qn ; t. This BeÂzier curve will be denoted by
u
u; t. Parameter u thus allows adjusting a curve to a desired length by deforming an initial curve according to a predefined configuration. The following is an example of modelling functions implemented into our system (see Figure 7). Points P0 ; . . . ; P4 are given. We define the following displacement functions: k
u Pk ;
i 0; 1; 3; 4 and 2
u P2 u
P2 ÿ 12
P0 P4 : The adjustment of a curve to a given length L is achieved by resolving for u the equation: `
u ÿ L 0: In this expression, `
u is the length of the BeÂzier curve defined by the control points
u calculated by the modelling function . The resolution of
this equation is achieved using the Newton-Raphson method. However, certain conditions must be met for the equation to be solvable. Clearly, the following conditions are sufficient for the equation to have a unique solution: (1) The length of the initial BeÂzier curve (corresponding to u 0) is less than the desired length L: `
0 < L:
Geometric modelling of garments 45
(2) None of the half-lines k intersect the polygon formed by points P0 ; P1 ; . . . ; Pnÿ1 except for their origin (Pk ): 8u > 0; k
u 62
P0 ; P1 ; . . . ; Pnÿ1
k 0; 1; . . . ; n ÿ 1: (3) The half-lines k do not intersect between themselves: j 6 k ) j \ k ;
j; k 0; 1; . . . ; n ÿ 1: In fact, condition (1) ensures that the initial length is less than the length sought, and conditions (2) and (3) lead to the fact that
u is a strictly increasing function. We used the automatic modelling method to shape the tubular part of the bodice, to adjust the waistband, and to configure the parts of the bodice that correspond to the shoulder sub-fragments. Construction of the model from measurements The modelling process can be divided into two parts. The first part consists in calculating curves in E3 , which correspond to the position of the measurement segments on the actual garment. These curves are called ``primary curves''. Second, these curves, as well as the parameters calculated during measurement, are used to derive the range of the exterior curves. The result is a frame, made up of the curves that are used to reconstruct surfaces. will be used to designate the range (i.e. the position) in E3 of The notation ! a 2-D object !, using the modelling algorithm. For example, if is a measurement segment, will be the corresponding curve in E3 .
Figure 7. Modelling function
IJCST 13,1
46
Figure 8. Tubular section
Calculation of primary curves Calculation of the primary curves is done one sub-fragment at a time, starting with the four tubular sub-fragments. Each primary curve is the range of a certain number of measurement segments placed end to end. However, a given segment is never associated to more than one primary curve. The curve modelling method described previously ensures that if is the primary P curve associated to measurement segments i
i 1; 2 . . . ; n, then `
I `
i . We will next use an additional index to distinguish objects (segments and points) relative to each fragment. Thus, Ri;f designates point Ri , as measured on fragments with index f (f 1; 2; 3; 4). The same goes for segments i;f and angles i;f . Calculation of the primary curves corresponding to the tubular subfragments is achieved from couples
i;f ; hi;f , asPmeasured on the pattern (i 0; 1; . . . ; n and f 1; 2; 3; 4). Consider di f `
i;f , the sum of the length of measurement segments at level i. For each i, a planar spline curve i is created, which is adjusted to length di by the curve modelling method, as explained here. The displacement functions k are defined from six initial points defined as P0
ÿb; 0; hi , P1
ÿb; b; hi , P2
b; b; hi , P3
b; 0; hi , P4
b; ÿb; hi and P5
ÿb; ÿb; hi , where b di =8. These points lie in the plane z hi . The displacement functions k are defined as follows: 0 P0 , 1
u P1 u
P1 ÿ P0 , 2
u P2 u
P2 ÿ P3 , 3 P3 , 4 P4 u
P4 ÿ P3 and 5 P5 u
P5 ÿ P0 (see Figure 8(a)). A BeÂzier curve is calculated by solving the equation `
u di , where is the modelling function associated to the displacament function k . This calculation is done for each level i 0; 1; . . . ; n. The curves corresponding to indexes i and i 1 are therefore placed in parallel planes at distance hi1 ÿ hi from each other. The distance from the back side to the front side is directly proportional to the measured length di and the distance from the left side to the right side is determined by the curve modelling method. One will notice that the presence of a dummy is not taken into account in the calculation. Figure 8(b) illustrates the final construction. Each curve i is associated to measurement segments i;f (f 1; 2; 3; 4). The P curve modelling method ensures that `
i f `
i;f . In other words, curve length in E3 effectively corresponds to its planar length.
Once the tubular sub-fragment has been calculated, we can continue with the other sub-fragments, focusing on the fragments on the left side of the bodice. Calculations are similar to those made for the right side. For each fragment, the position of the points for R1;f and R2;f (cf. Figure 6) is calculated using 2-D measurements. These measurements allow us to define two modelling functions 1 and 2 . Let us see how 1 is calculated, which also applies to 2 . Let Vi (i 1; 2) be the vector obtained by applying a rotation with angle 1;i to vector
0; 0; 1, in accordance with axis A R1;1 ÿ R1;2 (right-hand orientation). Moreover, let Bi R1;i Vi . Function 1 is defined by applying 0
u R1;1 , 1
u B1 u
B1 ÿ R1;1 , 2
u B2 u
B2 ÿ R1;2 and 3
u R1;2 . Figure 9(a) illustrates this calculation. The ranges of measurement segments 1;1 and 1;2 are derived from the solution R u 1 of equation `
1
u ÿ
`1;1 `
1;2 0. Consider u0 to be as 0 0 j i0
tdt `1;1 . Curves 1;1 and 1;2 are defined by 1;1
u 1
uu0 and 1;2
u 1
u0 u
1 ÿ u0 (u 2 0; 1). The ranges of segments 2;1 and 2;2 are calculated in the same manner, by solving for 2 in equation `
2
u ÿ
`
2;1 `
2;2 0. Once all the curves have been calculated, a partial frame is obtained, formed with primary curves, as illustrated in Figure 9(b). This frame pinpoints the position of each measurement segment in E3 . Bodices with an open centre are processed using a variable of the algorithm described above.
Geometric modelling of garments 47
Secondary curves and reconstruction of surfaces The last step of frame construction consists in calculating the range of the exterior curves in E3 . The range of an exterior curve in E3 is called ``secondary curves''. This calculation is derived from the primary curves, which serve to calculate the position of points sampled on the exterior curves in E3 , using the method previously described. Once the position of each point has been determined, the algorithm carries out the interpolation of a spline curve that passes through these points.
Figure 9. Shoulder modelling function
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We will illustrate the method by applying it to the part of the exterior curve that belongs to the shoulder sub-fragment associated to the fragment of index 1
i i;1 ). Let us consider point W of Figure 6(c) and its parameterisation in section regarding measurement. Let ui represent the
l1 ; l2 ; h, as calculated Ru value such as 0 i ji
t0 dt li . In other words, ui represents the value such as the length of the curve, between points i
0 and i
ui , is li . Consider Ui i
ui . The range of W in E3 is then calculated using the following formula (see Figure 10(a)): U1 ÿ U2 W U1 h : jU1 ÿ U2 j Clearly, the position of point W relative to curves 1 and 2 is approximately the same as that of point W relative to 1 and 2 , on the surface obtained by curving the shoulder sub-fragment. The result of the calculation of secondary curves is shown by the solid lines in Figure 10(b). The resulting frame supplies the curves that will serve to define the square Coons surfaces (Farin, 1996). This frame is defined in such as way as to yield a Coons surface for each sub-fragment (see Figure 10(c)). Figures A1 to A4 in the Appendix, show examples of garments calculated using our method. The calculation of each model took approximately 2-3 seconds on a 350MHz Pentium-II processor. Darts simulation To increase realism, the Coons surfaces of the geometrical model are transformed into a masses-springs system, to yield a physical simulation. The technique is based on the paper by Terzopoulos et al. (1987). The masses-springs system is achieved through a triangulation of the Coons surfaces. Each edge of the triangulation represents a spring and each point a
Figure 10. Calculation of the position of a point on an exterior curve and calculation of the surfaces
Figure 11. Dart-ressort intersection
mass. To calculate the natural length (at rest) of springs, a triangulation of the sub-fragments that corresponds to the triangulation of the Coons surfaces is performed. The natural length of a spring is derived from the length of the corresponding edge of the flat sub-fragment. This method maintains the initial sub-fragment area of the three-dimensional model. The masses-springs approach takes into account the existence of darts in the original pattern. On a fragment, darts are represented by closed, simple polygonal curves. The method consists in modifying the natural length of the springs of which the corresponding edge intersects a dart in the flat pattern, as shown in Figure 11. Polygonal curve c represents an interior dart on a fragment. Edge e
P0 ; P1 and curve c intersect at Q0 and Q1 . The natural length of the spring that corresponds to e should be jP0 ÿ P1 j. In the simulation, this value is replaced by jP0 ÿ P1 j ÿ jQ0 ÿ Q1 j. Figures A5 and A6, presented in the Appendix, show the effect obtained with this method. Conclusion The automatic character of the modelling algorithm led to the design of a program with a simple interface. This program does not require advanced knowledge of computer graphics software. Our methods also perform a rapid geometrical approximation of a garment based on the flat pattern. The nature of the geometrical approach is determinist, and therefore allows for positional control of modelled elements. By using measurements as described in this paper, the exact position of collars or lapels can be calculated based on the original flat pattern. Moreover, the user is not required to manipulate objects in a three-dimensional environment. Finally, the addition of the conversion of the geometrical model into a masses-springs system, as well as the inclusion of a virtual model, augments realism significantly. References Baraff, D. and Witkin, A. (1998), ``Large steps in cloth simulation'', Computer Graphics Proceedings, Vol. 32, pp. 43-54. Breen, D., DeVaul, R. and House, D. (1996), ``Towards simulating cloth dynamics using interacting particles'', International Journal of Clothing Science and Technology, Vol. 8 No. 3, pp. 75-94. Breen, D., House, D. and Wozny, M. (1994), ``Predicting the drape of woven cloth using interesting particles'', Computer Graphics, Vol. 28, pp. 365-72. Carrigan, M., Yang, M., Thalmann, N.M. and Thalmann, D. (1992), ``Dressing animated synthetic actors with deformable clothes'', Computer Graphics, Vol. 26 No. 2, pp. 99-104. Desbrun, M., SchroÈder, P. and Barr, A. (1999), ``Interactive animation of structured deformable objects'', Proceedings of Graphics Interface '99, pp. 1-8. Farin, G. (1996), Curves and Surfaces: A Practical Guide, Academic Press, New York, NY. Hardaker, C. and Fozzard, G. (1998), ``Towards the virtual garment: three-dimensional computer environment for garment design'', International Journal of Clothing Science and Technology, Vol. 10 No. 2, pp. 114-27.
Geometric modelling of garments 49
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Hinds, B. and McCartney, J. (1990), ``Interactive garment design'', The Visual Computer, Vol. 6, pp. 53-61. Kang, T.J. and Kim, S.M. (2000a), ``Development of three-dimensional apparel-CAD system. Part 1: flat garment pattern drafting system'', International Journal of Clothing Science and Technology, Vol. 12 No. 1, pp. 26-38. Kang, T.J. and Kim, S.M. (2000b), ``Development of three-dimensional apparel-CAD system. Part 2: prediction of garment drape shape'', International Journal of Clothing Science and Technology, Vol. 12 No. 1, pp. 39-44. Lafleur, B., Thalmann, M. and Thalmann, D. (1991), ``Cloth animation with self-collision detection'', Modeling in Computer Graphics, Springer-Verlag, Berlin. Ng, H. and Grimsdale, R. (1996), ``Computer techniques for modeling cloth'', Computer Graphics and Applications, Vol. 16 No. 5, pp. 28-41. Okabe, H., Imaoka, H. and Niwaya, H. (1992), ``Three dimensional apparel CAD system'', Computer Graphics, Vol. 26 No. 2, pp. 105-10. Provot, X. (1995), ``Deformation constraints in a mass-spring model to describe rigid cloth behavior'', Proceedings of Graphics Interface, pp. 147-54. Stylios, G. and Powell, N. (1996), ``Modeling the dynamics drape of garments on synthetic humans in a virtual fashion show'', International Journal of Clothing Science and Technology, Vol. 8 No. 3, pp. 95-112. Terzopoulos, D., Platt, J., Barr, H. and Fleischer, K. (1987), ``Elastically deformable models'', Computer Graphics, Vol. 21 No. 4, pp. 42-50. Volino, P., Thalmann, N.M., Jianhua, S. and Thalmann, D. (1996), ``The evolution of a 3D system for simulating deformable cloths on virtual actors'', Computer Graphics and Applications, Vol. 16 No. 5, pp. 205-14. Weil, J. (1986), ``The synthesis of cloth objects'', Computer Graphics Proceedings, Vol. 20, pp. 49-54. Appendix This appendix contains some illustrations of our system and corresponding flat patterns.
Figure A1. Geometrical model
Geometric modelling of garments 51
Figure A2. Sweater
Figure A3. Flat pattern corresponding to sweater appearing in Figure A2
Figure A4. Geometrical model
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Figure A5. Dart simulation
Figure A6. Flat pattern corresponding to bodice appearing in Figure A5
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Simulation of seam pucker on two strips of fabric sewn together S. Inui, H. Okabe and T. Yamaraka
National Institute of Materials and Chemical Research, Ibaraki, Japan Keywords Seam pucker, Simulation, Bending behaviour
Simulation of seam pucker
53 Received August 2000 Revised November 2000 Accepted November 2000
Abstract In our previous study, seam pucker simulation baased on mechancial calculation was proposed. Here, the simulation system is extended to consider collision between fabrics and seam pucker simulation of two strips of fabric is carried out. We adopt non-linear bending rigidity observed in actual fabric tests and obtained results much closer to the real results. With the consideration of collision and the improved treatment of bending rigidity, the following results were obtained. The wave length of wrinkles is more broadly distributed when material puckering is 0.96 or 0.94 compared to the case of 0.98. The wave length increases as the value of bending rigidity does and decreases as Young's modulus increases. In the case of two strips seam pucker, the distribution of the wave length is wider than the case of the single strip.
Introduction As has been discussed in many studies on seam pucker, prediction and control of its occurrence are of premier importance in the sewing process. We proposed a measurement technique of three-dimensional seam pucker shape and an objective evaluation method of seam pucker based on its shape (Inui and Shibuya, 1992). This method is effective for evaluation of existing seam pucker. However, it is more important to predict the occurrence of seam pucker when fabrics are sewn with sewing machines under various conditions. Theoretical or experimental studies have been conducted to investigate the relationship between the mechanical properties of fabrics and the development of seam pucker (Amirbayat, 1990; Amirbayat and McLaren Miller, 1991; Amirbayat and Norton, 1990; Stylios and Lloyd, 1989a; 1989b; 1990). In experimental studies, to control the conditions of materials is difficult because it is hard to prepare a set of fabrics such that all mechanical properties except one are the same. To overcome this difficulty, we proposed a method to simulate the occurrence of seam pucker by a computational model. In the simulation, the value of mechanical properties can be set without limitation. In our previous study (Inui and Yamanaka, 1998), we conducted the simulation concerning the seam pucker of a single strip of fabric, since collision between two fabrics was not modeled. We extended our simulation system to consider The authors would like to thank Professor Kamata of Jissen Women's University for giving them an opportunity to utilize industrial sewing machines. They also acknowledge Mr Matsushita of JUKI Corp. who kindly helped them with accurate advice in tuning the condition of sewing machines when they prepared seam pucker samples.
International Journal of Clothing Science and Technology, Vol. 13 No. 1, 2001, pp. 53-64. # MCB University Press, 0955-6222
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the collision and it became possible to simulate seam pucker of double strips of fabric as in real situations. The simulation was executed with various mechanical properties and the results were compared with those of a single strip of fabric. Seam pucker simulation The model and method of seam pucker simulation are basically the same as those in our previous study (Inui and Yamanaka, 1998). The virtual fabric in the simulation is treated as an elastic body. It is modeled as a thin plate, the thickness of which is very small compared to its length and width, and bending plays an important role in deformation. In the numerical calculation, the virtual fabric is divided into triangular elements and internal stresses of these elements are calculated. The tensile, shear and bending properties are taken into account in stress calculation. The potential energy is calculated from the total strain and each component of the force acting upon a vertex of a triangle is obtained as the partial derivative of the potential energy by the corresponding coordinate of the vertex. The stable shape of the fabric is determined as the formation of the vertices altered to minimize the potential energy. See the previous paper (Inui and Yamanaka, 1998) for details of elastic mechanical calculation. Dimension of fabric strip used for the simulations is 50mm 400mm. The fabric strip is divided into squares of 2.5mm 2.5mm. The square consists of two rectangular equilateral triangles and the triangle is treated as the fundamental element for calculation. Consideration of collisions As we have noted already, the collision between strips was not included in our previous study. In order to consider the collision problem, both the geometrical detection of colliding objects and the mechanical calculation of reacting forces on them are required. In the case of seam pucker samples, self collision within one strip of fabric never happens because the two strips sewn together mutually inhibit the self collision of the other. Therefore, only collisions between two different strips of fabric should be taken into account. We consider two types of collisions in this study. One is the collision between a vertex and a triangle. In this case, the area that a vertex in one of the strips can collide with is limited to a small region of the other strip of fabric. All the triangles in the area are listed and examined if they really collide with the vertex. Collisions are determined as follows (Figure 1): let triangle A be the object of collision. We determine a right prism D with height h and the base of which is triangle B, wider than the triangle A with width d. If a vertex is found in the right prism D beneath the triangle C, a collision may be considered to occur. The other type of collision is that of an edge and a triangle. In the same way as the collision of a vertex and a triangle, the triangles in the other strip of fabric that can collide with the edge are listed. Collisions are confirmed if they are penetrated by the edge.
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Figure 1. Collision detection of vertex and triangle
When collisions actually occur, the mechanical calculation of the force that pushes out the colliding vertex is required. In collision between a vertex and a triangle, the magnitude of the force is assumed to be a function of the distance from the vertex to the triangle. In collision between an edge and a triangle, the reaction force of collision is exerted on the vertices at the ends of the edge. The direction of the force is that of the normal vector of the triangle and its magnitude is set to be a certain constant value. Non-linear bending rigidity In the previous study, B value of KES-FB2 was utilized as bending rigidity in the simulation. When the results of the simulation were compared to the shape of real seam pucker samples, bending rigidity of the virtual fabrics in the simulation seemed to be too small. B value of KES-FB2 is defined as the slope of the graph of bending torque versus curvature in the range from 0.5cm-1 to 1.5cm-1. However, the curvature of wrinkles on real seam pucker samples seems to be under the range. The slope of the tangent to the graph of bending torque versus curvature is much steeper when we begin the bending test from the state in which fabric has not been bent yet. We approximate the graph with two functions M1
and M2
shown in Figure 2. They are defined in order that B value becomes the slope of M2
and 2HB value of KES-FB2 becomes the width of hysteresis curve. The way of mechanical calculation about bending is modified with the use of bending torque from the approximated function instead of constant bending rigidity. The potential energy derived from bending is expressed as XZ
Mi
ki dki si ; Ub i
IJCST 13,1
56 Figure 2. Approximated bending curve
where si is the area of i-th triangular element. M curvature and those are defined as follows, 2 2 u 3 M
u u 6 6 v 7 M 4 M
v 5; k 4 v M uv
uv
is bending torque, is 3 7 5:
uv
The subscript u; v means directions of warp and weft as curvilinear coordinates for pattern. We neglected M uv because it has little effect on the result of the simulation. The curvature is calculated from the shape and formation of triangular elements and the value of bending torque is determined from the approximated function. The bending force f bj exerted on a vertex j is derived as gradient of the potential energy, @Ub @Ub @Ub ; ;ÿ ;ÿ f bj ÿ @xj @yj @zj where
xj ; yj ; zj is the coordinates of vertex j. Relationship between mechanical properties and seam pucker occurrence We prepare single and double strips of fabric seam pucker samples by sewing real fabrics with a single needle sewing machine (JUKI DDL-5571N). At the same time, simulations are carried out using the mechanical properties obtained from the measurement of the fabric which is used for making real seam pucker samples. The symbols of mechanical properties are shown in Table I, and the conditions in Table II. We also measured the shape of wrinkles along the seam line of real seam pucker samples by a laser displacement meter. The simulation is carried out with the condition that coordinates of all the vertices on the seam line are fixed to the measured value. The other vertices are repeatedly moved according to the calculation and then finally seam pucker shape is obtained. Figure 3 shows the real seam pucker samples of single and
double strips of fabric, and Figure 4 shows the corresponding results of the simulations. Except the region along the center line, where mesh size of the simulation ought to be much smaller to simulate very small wrinkles in actual samples, the results of the simulation well agree with the real shapes of seam pucker. Further, simulations are executed with different conditions and the influence of the mechanical properties upon the shape of seam pucker is observed. The simulation conditions are shown in Table III. The values 0.015, 0.06 and 0.3gf Symbol
Description
Unit
MP Eu , Ev G B u , Bv 2HBu u , v
Material puckering Young's modulus (u; vdirection) Shearing rigidity KES-FB2B (u; v direction) KES-FB2 2HB (u; v direction) Poisson's ratio (u; v direction)
(±) (gf/cm) (gf/cm) (gf cm2/cm) (gf cm/cm) (±)
Symbol
Single
MP Eu Ev G Bu 2HBu Bv 2HBv u , v
0.978
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Table I. List of symbols
Double 11,800 4,068 0.535 0.0376 0.0318 0.0227 0.0167 0.8
0.979
Table II. Mechanical properties of the real fabric
Figure 3. Real seam pucker samples (single strip ± left and double strips ± right)
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58 Figure 4. The result of the simulations with properties of a real fabric (single strip ± left and double strips ± right)
Table III. Simulation specifications
No.
MP
F Mp1 Mp2 Mp10 Mp20 Be1 Be2 Te1 Te2
0.96 0.98 0.94 0.98 0.94 0.96 0.96 0.96 0.96
Eu
Ev
5,000 5,000 " " " " " " " " " " " " 1,000 1,000 20,000 20,000
G
u
v
Bu
2HBu
Bv
2HBv
0.9 " " " " " " " "
0.8 " " " " " " " "
0.8 " " " " " " " "
0.06 " " 0.015 " " 0.3 0.06 "
0.04 " " 0.007 " " 0.2 0.04 "
0.06 " " 0.015 " " 0.3 0.06 "
0.04 " " 0.007 " " 0.2 0.04 "
Note: " = The value is the same as above
cm2/cm are used for B value of KES-FB2 in the simulations. 2HB value is determined with reference to the real fabrics that have similar B value. Under these conditions, Poisson's ratio for tensile is assumed to be 0.8. In these simulations, the strip of fabric is shrunk in longitudinal direction at the ratio of material puckering as the initial state of simulation. (Material puckering is the ratio of strip length after sewing to that before sewing.) The vertices on the center line are fixed during calculation. Figure 5 shows the results of the simulation under the condition F. ``s'' as the last character of the simulation condition name indicates the seam pucker of a single strip of fabric and ``d'' indicates that of double strips of fabric, such as Fs or Fd. The wave shape of wrinkles on a line located 2.5cm from the seam line is Fourier transformed. Here, the wrinkles are considered to be waves and we call the squared amplitude of the wave as ``power''. Figure 6a shows the power spectra of Fs and Fd. Accumulated distribution of power as a function of the number of waves on a strip of fabric is shown in Figure 6b.
Simulation of seam pucker
59 Figure 5. The result of simulations Fs (single strip ± left) and Fd (double strips ± right)
Figure 6a. Power spectra of the wrinkle shape of the simulation results Fs and Fd
Figure 6b. Accumulated distribution of power under the conditions Fs and Fd
In the figure, the slope of the graph of double strip seam pucker is gentler than that of the single strip. This shows the effect of the collisions between upper and lower fabric. In the result of the double strips of seam pucker simulation (Figure 5), wrinkles of shorter wave length compared to the case of single strip are observed. At the same time, in other parts of the strip of fabric, wrinkles flattened and connected to form wrinkles of longer wave length are found. Those are considered to be the reasons that the slope of the graph of double strips of fabric seam pucker is more gentle than that of single strip seam
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Figure 7a. Accumulated distribution of power under the conditions Mp1s and Mp1d
Figure 7b. Accumulated distribution of power under the conditions Be1s and Be1d
Figure 8. The reult of simulations Mp1s (single strip ± left) and Mp1d (double strips ± right)
pucker. The same tendency is observed under the conditions Mp1 and Be1 (Figure 7). Under the conditions Mp1, F and Mp2, all the properties are the same except material puckering. The results of the simulation under the condition Mp1 is shown in Figure 8. The graphs of accumulated distribution of power of double strips seam pucker under those conditions are shown in Figure 9a. The slope of the graph under the condition Mp1 where material puckering is the largest is steeper than that of F or Mp2. The graphs of accumulated distribution of power
under another condition set of Mp10 , Be1 and Mp20 , in which only material puckering is different, are shown in Figure 9b. The graph is shifted to the right side as material puckering decreases. The influence of material puckering is clearly shown in this case. Under the conditions Be1, F and Be2, all the properties are the same except bending rigidity. The resulting shapes of the simulation under the condition Be1 are shown in Figure 10. The graphs of accumulated distribution of power
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61
Figure 9a. Accumulated distribution of power under the conditions Mp1d, Fd and Mp2d
Figure 9b. Accumulated distribution of power under the conditions Mp10 d, Be1d and Mp20 d
Figure 10. The result of simulations Be1s (single strip ± left) and Be1d (double strips ± right)
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Figure 11. Accumulated distribution of power under the conditions Be1d, Fd and B2d
Figure 12. The result of simulations Te2s (single strip ± left) and Te2d (double strips ± right)
Figure 13. Accumulated distribution of power under the conditions Te1d, Fd and Te2d
under those conditions are shown in Figure 11. The graph is shifted to the left side as bending rigidity increases. It indicates that wave length of the wrinkles of seam pucker increases as the value of vending rigidity does, and this coincides with the appearance of the results of the simulations. Under the conditions Te1, F and Te2, only Young's modulus is changing. The resulting shapes under the condition Te2 are shown in Figure 12. The graphs of accumulated distribution of power under those conditions are shown in Figure 13. The graph is shifted to the right side as Young's modulus
increases. This means that the wave length is longer when Young's modulus is smaller with the same value of bending rigidity. The shape of the wrinkles is thought to be formed with the balance of tensile and bending. In the case of a small Young's modulus, wrinkles of the small wave length caused by bending cannot be formed, probably because fabric is easily stretched. On the other hand, in the case of a large Young's modulus, wrinkles of small wave length are formed by bending because the abric is hard to stretch. In the previous study, the effect of Young's modulus was not clear because bending rigidity was underestimated. Conclusion In the simulations of the previous study, the model of seam pucker consisted of a single strip of fabric and B value of KES-FB2 was used for bending rigidity. In this study, we extended the simulation system to cover the seam pucker model of double strips of fabric and improved the treatment of bending rigidity because it seemed to be underestimated. Non-linear function is adopted to approximate the observed graph of bending torque versus curvature and modified the calculation about bending. The shape of wrinkles of seam pucker is considered as wave and frequency analysis was introduced. When material puckering is 0.96 or 0.94, power spectra of shape of wrinkles are more broadly distributed compared to the case when material puckering is 0.98. The wave length increases as the value of bending rigidity does. On the other hand, shorter waves appear when Young's modulus is large. The wider distribution of wave length of wrinkles in the result of double strips seam pucker simulation compared to that of single strip is due to the collisions between upper and lower fabric. Simulations with the properties of real fabric are executed and similar shapes as real seam pucker samples are obtained. In the result of the simulation of double strips of fabric with the properties of real fabric, the effect of collisions of upper and lower fabric is not observed despite the small bending rigidity. This is probably because the wave length of wrinkles in the result is rather long owing to the effect of the seam line shaped as the real one. References Amirbayat, J. (1990), ``An energy approach to the instability problem of overfed seams, part 1'', International Journal of Clothing Science and Technology, Vol. 2 No. 1, pp. 21-5. Amirbayat, J. and McLaren Miller, J. (1991), ``Order of magnitude of compressive energy of seams and its effect on seam pucker'', International Journal of Clothing Science and Technology, Vol. 3 No. 2, pp. 12-17. Amirbayat, J. and Norton, M.L. (1990), ``An energy approach to the instability problem of overfed seams, part 2'', International Journal of Clothing Science and Technology, Vol. 2 No. 2, pp. 7-13. Inui, S. and Shibuya, A. (1992), ``Objective evaluation of seam pucker'', International Journal of Clothing Science and Technology, Vol. 4 No. 5, pp. 24-33. Inui, S. and Yamanaka, T. (1998), ``Seam pucker simulation'', International Journal of Clothing Science and Technology, Vol. 10 No. 2, pp. 128-42.
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Stylios, G. and Lloyd, D.W. (1989a), ``The mechanism of seam pucker in structural jamming woven fabrics'', International Journal of Clothing Science and Technology, Vol. 1 No. 1, pp. 5-11. Stylios, G. and Lloyd, D.W. (1989b), ``A technique for identification of seam pucker due to fabric structural jamming'', International Journal of Clothing Science and Technology, Vol. 1 No. 2, pp. 25-7. Stylios, G. and Lloyd, D.W. (1990), ``Prediction of seam pucker in garments by measuring fabric mechanical properties and geometric relationship'', International Journal of Clothing Science and Technology, Vol. 2 No. 1, pp. 6-15.
The current issue and full text archive of this journal is available at http://www.emerald-library.com/ft
A remote, on-line 3-D human measurement and reconstruction approach for virtual wearer trials in global retailing G.K. Stylios, F. Han and T.R. Wan
Approach for virtual wearer trials 65 Received March 2000 Revised October 2000 Accepted October 2000
Heriot-Watt University, Scottish Borders Campus, Galashiels, Scotland, UK Keywords Measurement, Databases, Image processing Abstract A powerful 3-D system has been developed for on-line 3-D human measurement and reconstruction that interferes with a SQL Server database for virtual wearer trials in global retailing. In this research, 3-D body profiles have been captured and analysed using an on-line image measurement and processing system developed in this research and then stored in the database system. A parametric geometric human model has been devised with an effective search algorithm that utilises body measurements obtained on-line or retrieved from the database. A SQL server database system has been constructed with user friendly interfaces which enables users to collect, manage and analyse all related information including human body images.
1. Introduction The globalisation of information sharing has been a strong motivation for the rapid expansion of the World Wide Web. The Internet provides us access to an unprecedented amount of information so that the world seems to be getting more and more data centred. Tremendous potential has arisen with the development of virtual reality (VR) environments, e-commerce and Internet business. The combination of computer virtual technologies and database Internet techniques will provide the next generation of special effects in TV/ film/advertising/games, and augmented reality environments. The fashion industry is in urgent demand of this technology, because textile and fashion products have a short market life and their success is dependent on fashion styles and price. The ultimate aim is to be able to change products not only by season and design, but also by market and customer and to be able to customise products just in time. Global retailing or remote shopping complies with the requirement in the fields of fashion, textiles and apparel industries, whose concept is to enable customers to purchase garments by conducting ``virtual wear trials'' using their own body size and shape to try the garments. Although research for virtual human modelling has been successfully developed in some fields, only a few research projects try to explore more The authors would like to thank Leona Collins of the Printed Stitch Studio, Lesley Linsey and Mark Timmins for their participation during image preparation of the female body models.
International Journal of Clothing Science and Technology, Vol. 13 No. 1, 2001, pp. 65-75. # MCB University Press, 0955-6222
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appropriate techniques for on-line 3-D human measurement and reconstruction. An effective, fast and flexible system for on-line 3-D human measurement and reconstruction has not been widely available yet. The goal of our work is to develop such a system aimed to interface with global retailing for on-line parametric geometric 3-D virtual human body modelling, image measurement and data management based on SQL Server database. Although there are a number of research efforts in the field of 3-D virtual human body construction, most of them use rather complex body models, which need huge amounts of body data. These research efforts (Armstrong and Green, 1996; Badler et al., 1993; Volino and Magnenat-Thalmann, 1998; Kalvin and Talor, 1996; Stylios and Wan, 1999) have shown some success in the modelling and animation processes; however, they appear to be complex and inconvenient when changing the shape and size of the human body (Kalra et al., 1998; Emeering et al., 1998). Moreover, thousands of vertices are needed to specify a reasonably detailed human body, which also makes storage and communication difficult and inconvenient. The problem becomes even more difficult in on-line 3-D human reconstruction. Consequently, effort is needed in developing a compact, parameterised body model suitable for fast and easy on-line communication. To cope with these new challenges, there is a need to explore a new human body modelling principle. In this approach, the date structure should be changed for increasing versatility, which means that the body modelling should be changed in a convenient way under given human body data. Volino et al. (1996) have noticed these new research requirements. Only in a few projects a certain level of versatility is provided, but the adjustments and related data structures are complex (Volino et al., 1996; Kalra et al., 1998). Computer-supported collaborative work (CSCW) often involves interaction and discussion of computer-generated information such as models, simulations, annotations, and data accessed in shared virtual environments (Earnshaw et al., 1998). These issues present significant and important developments in computer animation for virtual humans, particularly in the area of networked environments with distributed users. These developments have great potential in the areas of shared environments and interactions. However, up to now, only very few research projects could successfully combine modelling work with on-line database applications. In this paper, we report on a new approach to human body modelling based on a compact parameterised body suitable for fast and easy on-line communication. 2. The principle of on-line human body measurement and reconstruction There are three important areas which, although useful as stand-alone solutions, when integrated can introduce new ways of designing, selling and producing garments. Global retailing is an area of enormous interest because it challenges the conventional way of buying, selling, producing
and distributing clothes. The three areas are the simulation and animation of garments and humans, the on-line exchange of technical and trade data, and the on-line synthetic human modelling system (Stylios and Wan, 1999). Our project is based on a parametrical, general geometric model of a human. In a flexible and convenient way either a man or a woman can synthetically change in body size and shape on-line by real data, which can be provided by the user of the system who in most cases is the reconstructed human as well. Our research is based on developing a human model, which allows the 3-D reconstruction of the human body from 2D photos by imaging techniques. The data structure of the human model should be changed in order to represent the different shapes of individuals. Initial work has thus been concentrated on constructing a compact, parametrical, geometric virtual human body model that is easily changed under different human body data. We have achieved a convenient image measurement technique to obtain body data needed for modelling a body from 2D photos of a person. In order to implement the system, we constructed a SQL Server database in which the user is able to collect, classify, analyse and manage data. Our aim is to integrate them into a new system of on-line human body data measurement, collection, modelling reconstruction and visualisation. They constitute a comprehensive, remote, on-line human body modelling system for realistic 3-D virtual human modelling based on 2D photos for applications in a number of areas and particularly in global retailing or home shopping of clothes using virtual wearer trials. The on-line human body measurement and reconstruction system integrates the following parts: image processing and 3-D body profile recognition, a body reconstruction system, human head reconstruction and image mapping, and data storage and retrieval, as show in Figure 1.
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Figure 1. The on-line human body measurement and reconstruction system
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The paper is organised in two sections: (1) 3-D human reconstruction; (2) the principle of the measurement database system. We mainly discuss the work concerned with the geometrical body modelling and body measurement data storage and retrieval systems in this paper. The image processing system, human head reconstruction and 3-D face mapping will be reported later. 3. 3-D human reconstruction The algorithm of 3-D body reconstruction is based on the 3-D imaging information obtained via an automated image analysis system developed in this research work. In this system the front, side and back images of a person are obtained via a CCD camera or other device and are sent to the image recognition unit. More detailed key measurements are then carried out based on these raw images which are used for the reconstruction of virtual humans. The human modelling work in this research consists of a number of key tasks, in terms of representation of the body profiles by space curves, 3-D surface generation and solid body modelling. The approach presented in the current research appears powerful and efficient in handling these tasks. 3.1 Representation of body profiles Human body modelling involves smooth curves and surfaces. In order to model augmented humans, a mathematical description of a geometrical body is unavoidable, especially if the task is an on-line one. There are tremendous efforts and applications in the area of surface modelling, since BeÂzier curves were invented by BeÂzie and his method was applied to modelling 3-D car shapes in the Renault car factory. Generally, although there are many different types of curves that can be used for surface modelling, B-spline curve forms are chosen for body reconstruction in this research by virtue of their broad application and flexibility in the area of 3-D surface modelling. 3.2 Representation of space curves Body profiles obtained by image processing systems can be represented as parametrical curves, which define points on a 3-D curve by using polynomials in a single parameter. Therefore a body profile in this research work can be represented as a B-spline form: m X Pi Bi
t; 0 t 1: Q
t i0
Where t is a parameter, varies from 0 to 1. Without loss of generality, t is restricted to the [0,1] interval. Bi are the blending functions and Pi are the control points. Figure 2 shows a typical B-spline curve segment.
3.3 Profile fitting algorithm Generally speaking, whatever approach is used, one can only approximate body profile curves. The algorithm to determine the fitting curves that are approximate to the body profiles can be written as follows: (1) Input of body profiles including front, side and back image profiles and key body cross-section curves. (2) Divide each curve into feature-related curve segments and code them according to reconnection order.
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(3) Design initial B-spline curve segments to each body feature-related curve segment using data sampled on body profiles (4) Calculate the mapping errors caused by the differences between approximate curves and original body profiles. (5) Produce final approximated B-spline curves, if the mapping errors meet the pre-assigned criteria. Otherwise adjust the control points one step and go to step 3. 3.4 Surface modelling and solid modelling techniques for 3-D human reconstruction Body surface patches can be generated based the 3-D curves previously determined, as discussed above. A general form of body surface can be represented by: n X m X Pi;j Bi;j
s; t: Q
t; s i0 j0
Where, Pi;j is an array of control points and Bi;j
s; t are basis functions, which can be evaluated by: Bi;j
s; t Bi
s Bj
t: Where, Bi
s and Bi
s are the previously defined B-spline curves. Figure 3 shows a typical example of B-spline surface patch generation.
Figure 2. A typical B-spline curve segment
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3.5 3-D body reconstruction Now, we are ready to deal with the solid body modelling task based on the 3-D surface patches. Generally, a surface collection does not necessarily bound a closed volume, however, in human modelling, it is important to distinguish between the inside and the outside of the surfaces of the body. For example, one may need to determine whether two parts of the body, say an arm and shoulder, will interfere with each other. Figure 4 shows a real female body model in back view, front view and side view. Figure 5 shows the female body model reconstructed by the system using the measurements based on the images of the female body. Figure 6 shows the polygon mesh form of the model in front view. Figure 7 shows a real back, front and side views of another female body different in size and shape. Figure 8
Figure 4. The back, front and side views of a real female model
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Figure 5. The back, front and side views of a female model generated by the system
Figure 6. A polygon mesh form front view of the same female model generated by the system
shows the computer generated model in back, front and side views using the measurements based on the images of the female body shown in Figure 7. The real models and the reconstructed models are in close agreement, verifying the validity of the system. 4. The principle of the measurement database system For on-line reconstruction of humans for augmented reality environments, SQL Server 7.0 provides the necessary platform to track all projectrelated information and could have potential applications throughout the
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Figure 7. The back, front and side views of a real female model
Figure 8. The back, front and side views of a female model generated by the system
Internet. There are a variety of reasons for the selection of the present database using SQL Server over competing databases, including ease of implementation, low administration and maintenance, scalability, reliability, improved data-warehousing capabilities, and reasonable price. SQL Server provides data storage and display, including image data across the network. SQL server was used to create the relational database in our project, which contains several tables made up of rows and columns. Structured Query Language (SQL) (Sawtell et al., 1999) is used to access databases interactively
or in a program for queries-requests for information from one or more databases, compare information in various tables of a relational database and extract results made up of data fields from one or more tables. It is also possible to use SQL to add, delete, or change information. The database in this project consists of several tables which include individual information, such as: name, gender, age, height, 2D body images and some key body feature data from body image measurements, for example their height, breast size, waist size, etc. The data measurement may take mono camera or laser scanner data, which can provide detailed human body data information for virtual model construction. The user can manage the database by a user interface created. Figure 9 shows the main interface with fundamental functions such as human data search and human reconstruction. A number of buttons are used and linked to the database designed according to SQL stored procedures. When a user clicks a button, a sub-interface will be displayed and corresponding functions will be activated. For example, when a user wants to search the database, you can simply click the human data search button then a sub-interface for search will be displayed, as shown in Figure 10a. On this sub-interface there are several edit boxes for different search fields. In this way, a user may initiate a search query and then click the submit query button to submit his or her queries. To look at an example, when a user inputs Male, 170 and 180 to the edit boxes, then with a click of the submit query button, another sub-interface will be opened. Data results satisfying the search range will be displayed, as shown
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Figure 9. The main interface
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Figure 10. a) The sub-interface for search; b) The subinterface for result
in Figure 10b. When a user clicks the button on his or her name, his or her individual details will be displayed. To generalise the process, we first created a stored procedure in SQL Server, then the stored procedure has been called with C++ functions. A typical example is shown as follows: List 1: SQL Stored Procedure CREATE PROCEDURE MySearch AS SELECT MyTAB.Name FROM MyTAB WHERE Gender = `Male' AND Height BETWEEN 170 AND 180; List 2: Call the SQL Stored Procedure Function Cstring CmyInterfaceSet::GetDefaultSQL() { return_T (``{CALL MySearch} ''); } First, the SQL finds the rows where the gender is male and the height is between 170 and 180, then it takes this new list of rows, but it only selects MyTAB.Name column to display on that interface. Here, the WHERE clause was used to specify that only certain rows of the table are displayed, based on the criteria described in the WHERE clause. One may want to change this default SQL so that it can call the stored procedure. In ClassView the Class CMyInterface may be chosen and then the GetDefaultSQL function is edited as List 2. The function will call your stored procedure and display the search result on the interface.
5. Discussion and conclusion A new approach for the measurement and reconstruction of a 3-D human body is presented and its potential for remote on-line applications such as in virtual wearer trials for global retailing has been discussed. A parametric geometric body model has been devised with a new algorithm that uses on-line body measurements. The complete 3-D shape of the human model can then constructed and the detailed information concerning 3-D human body measurements is obtained for virtual wearer trials. A database has been constructed in which the user can access human body data and carry out data collection, analysis and management. Research results for the reconstruction of the human face and its integration with this system will be reported elsewhere. References Armstrong, W. and Green, M. (1996), ``Dynamics for animation of characters with deformable surfaces'', Graphics Interface. Badler, N.I., Phillips, C.B. and Webber, B.L. (1993), ``Simulation humans'', Computer Graphics Animation and Control, Oxford University Press, Oxford. Earnshaw, R., Magnenat-Thalmann, N., Terzopoulous, D. and Thalmann, D. (1998), ``Computer animation for virtual humans'', IEEE Computer Graphics and Applications, September/ October, pp. 20-3. Emeering, L., Boulic, R. and Thalman, D. (1998), ``Interacting with virtual humans body action'', IEEE Computer Graphics and Applications, January/February, pp. 61-75. Kalra, P., Magnenat-Thalmann, N., Moccozet, L., Sannier, G., Aubel, A. and Thalmann, D. (1998), ``Real-time animation of realistic virtual humans'', IEEE Computer Graphics and Applications, September/October, pp. 42-55. Kalvin, A.D. and Talor, R.H. (1996), ``Superfaces: polygonal mesh simplification with bounded error'', IEEE Computer Graphics and Applications, May, pp. 64-77. Sawtell, R., Mortensen, L. and Waymire, R. (1999), Sams Teach Your SQL Server 7 in 21 days, Sams. Stylios, G. and Wan, T.R. (1999), ``Artificial garment for synthetic humans in global retailing'', Digital Media Futures, Bradford, 13-15 April. Volino, P. and Magnenat-Thalmann, N. (1998), ``The SPHERIGON: a simple polygon patch for smoothing quickly your polygonal meshes'', Computer Animation'98 Proceedings. Volino, P., Magnenat-Thalmann, N., Jianhua, S. and Thalmann, D. (1996), ``An evolving system for simulating clothes on virtual actors'', IEEE Computer Graphics and Applications, September, pp. 42-51.
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The current issue and full text archive of this journal is available at http://www.emerald-library.com/ft
A study on the needle heating in heavy industrial sewing Part 1: analytical models Qinwen Li
Productive Design Services Inc., Windsor, Ontario, Canada
Evangelos Liasi
Ford Motor Company, Dearborn, Michigan, USA
Needle heating in heavy industrial sewing 87 Received February 2000 Revised January 2001 Accepted January 2001
Hui-Jun Zou
Department of Mechanical Engineering, Shanghai Jiatong University, Shanghai, People's Republic of China, and
R. Du
Department of Industrial Engineering, University of Miami, Florida, USA Keywords Sewing, Needle, Heat Abstract In heavy industrial sewing, needle heating has become a serious problem that limits the further increase of the sewing speed, and hence the productivity. The high temperature in the needle can degrade the strength of the thread. At the same, it may cause the wear of the needle eye, which would further damage the thread. It can also scorch the fabric, as well as temper and weaken the needle itself. Therefore, it is important to develop a model that can predict the needle heating and, hence, find remedies to minimize its effects. According to a literature survey, most research on needle heating focuses on experimental methods, such as infrared radiometry, infrared pyrometry, etc. This paper is the first part of our research on needle heating. In this paper, two analytical models are presented: the sliding contact model and the lumped variable model. These models are relatively simple and easy to use. Given needle geometry, sewing condition, and fabric characteristic, they can predict the needle temperature rise starting from initial heating to steady state. The simulation results are rather accurate. Hence, the models can be used to quickly identify the potential needle heating problems on the shop floor. In Part 2 of our study, a finite element analysis (FEA) model is presented together with the experiment results.
1. Introduction Industrial sewing is one of the most commonly used manufacturing operations. Its applications can be found in the manufacturing of garments, shoes, furniture, and automobiles, just to name a few. Everyday, millions of products, ranging from shirts to automotive airbags, are sewn. Hence, even a small improvement may result in significant corporate benefits. This work was completed when the authors worked at the University of Windsor in Windsor, Ontario, Canada. This work was partially supported by Delphi Lighting and Interior Systems, Peregrine Canada, and the Natural Science and Engineering Research Council of Canada (NSERC). In particular, the authors would like to thank Charles Beauchampe, who made the success of this project become possible. Many thanks are extended to Annette, an expert sewer from Peregrine Canada as well as Mr Dan Simon who has graciously carried out the experiment.
International Journal of Clothing Science and Technology, Vol. 13 No. 2, 2001, pp. 87-105. # MCB University Press, 0955-6222
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In this study, we focus on heavy industry sewing, such as sewing of automobile seat cushions, backs and airbags. It requires not only high productivity, but also high sewing quality (i.e. good appearance and long-lasting stitches). Typically, the material being sewn includes single and multiple plies of synthetic fabric or leather, and sometimes backed with plastics. These materials are much more difficult to sew compared to ordinary sewing applications. In recent years, in order to increase the sewing productivity, high speed sewing has been used extensively. Currently, sewing speeds range from 2,000~6,000rpm. In heavy industrial sewing, typical sewing speeds range from 1,000~3,000rpm. A problem that accompanies the high speed sewing is broken thread. It is perhaps the most common defect encountered on the shop floor. Broken thread may be caused by various reasons; however, excessive needle heating is definitely one of the leading factors. When the needle penetrates the fabric at a rate of thousands of times per minute, needle heating due to the friction between the needle and the fabric is severe. The friction generates heat, part of which is absorbed by the fabric and part by the needle. The heat absorbed by the fabric is spread out along the seam, but the heat absorbed by the needle accumulates. Depending on sewing conditions the maximum needle temperatures range from 1008C~3008C. This high temperature weakens the thread, since thread tensile strength is a function of temperature (Liasi et al., 1999). At the same, the needle heating may cause the wear of the needle eye, which would further damage the thread. It has been observed that the needle temperature exceeded the melting point of the synthetic sewing thread, resulting in broken threads. In addition, the hot needle can cause the formation of creases in the sewing thread, causing the loop formed by the sewing thread to be improperly shaped and the hook not entering the loop. This results in skipped stitches. The hot needle can also initiate damage in the fabric, such as leaving burn marks on natural fibers, leaving a weakened seam or melted residue on the fabric surface. Decreasing the sewing speed can reduce the needle heating; however, it will also decrease the productivity. Clearly, understanding the needle heating and, hence, finding remedies is very important and will result in positive productivity and quality gain. Much research has been conducted on needle heating, such as measuring the needle temperature, studying the heating mechanisms, as well as correlating the sewing parameters and fabric properties to the peak needle temperature. According to a literature survey, most of the studies used experimental methods, such as thermal couple, temperature-sensitive material (Hersh and Grady, 1969), IR radiometry (Liasi et al., 1999), and infrared pyrometer (Howard and Parsons, 1968; Howard et al., 1971; Najafi et al. 1994). These experimental methods are accurate and reliable (Hurt and Tyler, 1972). However, they have a major limitation: they are expensive (e.g. an IR radiometry measurement device costs thousands of dollars) and time-consuming (in order to cover various sewing conditions). Hence, it is inconvenient for shop floor applications. In addition, they cannot directly reveal the causes of the needle heating. To overcome the limitations of the experimental methods, analytical models are desirable. With such a model, one can predict the needle temperature rise
during the entire sewing operation; and understand how the sewing parameters Needle heating in (such as the sewing speed, the fabric material, the needle geometry and the heavy industrial needle cooling) affect the needle heating. Furthermore, the model can provide sewing useful information in optimizing the sewing operations and assisting the design of needles and needle cooling systems. This paper presents our study on needle heating. It consists of two parts. 89 Part 1 presents two analytical models: the sliding contact model and the lumped variable model. Part 2 presents a finite element analysis (FEA) model as well as the experiment results. Part 1 of this paper consists of five sections. Section 2 describes the basic thermal mechanics of the needle heating. Sections 3 and 4 present the sliding contact models and the lumped variable model respectively. Finally, section 5 contains a short conclusion. 2. The basic thermal mechanics of needle heating The needle heating process is a complicated process. Needle temperature arises as the sewing process progresses, until an equilibrium state is reached. During the process, the needle temperature varies in every stitch as the needle punches through and withdraws from the fabric. Figure 1 illustrates the thermal dynamics system of the needle heating. More specifically, the heat sources include the following: . The heat flux generated from the friction between the fabrics and the needle. Note that with the motion of the needle, the fabric position relative to the needle is changing during a stitch and, hence, the position of the heat flux is time-dependent. . The heat flow generated from the friction between the thread and the needle-eye when the thread is in tension. Since the thread tension is varying within a stitch, the heat flow is also time-dependent. On the other hand, the heat sinks include: . The convection of the portion of the surface of the needle that is not in contact with the fabrics. Since the relative position of the needle to the fabric is time-dependent, the convection is time-dependent.
Figure 1. Illustration of needle heating problem
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.
.
The heat conduction in the needle from the higher temperature points to the lower temperature points. Again, since the relative position of the needle to the fabric varies, the heat conduction is time-dependent. The heat conduction to the fabric, as the needle temperature is higher than the fabric. The heat conduction to the thread, which happens when the thread loosely passes through the needle eye. The radiation from the needle surface to the environment.
From the analysis above, it is evident that both heat sources and heat sinks are time-dependent. Therefore, the needle heating is a transient heat transfer problem. As illustrated in Figure 2, in a cylindrical coordinates system (r, , Z), the needle can be approximated as a cylinder: N = {r0 r > 0, 2 0, z1 Z z2} and the fabric can be approximated by an infinite plate with a thickness of . The needle heating problem can be described as a thermal dynamics problem as defined below: @T @T k @ 2 T 1 @T 1 @ 2 T @ 2 T
1 U
t @t @Z c @r2 r @r r2 @ 2 @Z 2 Initial conditions: T T0 ; when t 0; for all N Boundary conditions: k
@T h
T ÿ T0 0; when r r0 ; Z 6 =2; @r k
Figure 2. The coordinate system for the needle heating model
@T q
t 0; when r r0 ; Z =2; @r
@T 0; when Z a
sin !t sin !0 t @Z where: a is the amplitude of a sewing stroke, in (m); c is the specific heat of the needle, in (W/(kg2K)); h is the convection coefficient of the needle, in (W/(m2K)); k is the thermal conductivity of the needle, in (W/(mK)); q(t) is heat flux due to the friction, in (W/m2); t is the time, in (s); T is the needle temperature, in (K); U(t) is the needle velocity, in (m/s); is the fabric thickness, in (m); is the material density of the needle, in (kg/m3); ! is the frequency of the needle motion, in (rad/s); and !0 is the frequency of the needle motion at nominal speed, in (rad/s). Note that since the boundary conditions are time-dependent and the needle geometry is complicated, it is very difficult, if not impossible, to solve this model analytically. The alternatives are either to develop a simplified model, or to solve it numerically. According to the literature survey, two simplified analytical models have been developed. In Howard and Parsons (1968), a simple model was established for estimating the needle heat loss after the needle temperature achieved an equilibrium state. Simmons and Keller (1980) developed an empirical formula for needle heating process using mathematical regression, which could barely be called an analytical model. These models are rather simple and did not include many important factors, such as the heat partition between the needle and the fabric, as well as the transient process of the sewing operation. There are a number of related research works. For example, since the heat due to friction between the needle and the fabric is the main heat source, the friction force is very important (Stylios and Xu, 1995). Malet and Du (1998) developed a FEA model to analyze sewing forces, by which the friction force can be obtained. As shown in Perry (1963), convection is the major part of heat dissipation. Since the sewing process runs at high speed, the convection coefficient is dominated by the sewing speed. In addition, when a needle cooling system is installed, forced convection reduces the needle heating (Hersh and Grady, 1969). Sewing thread plays a complicated role in needle heating. Generally, the thread is a heat sink. This is because the cold thread goes through the hot needle eye loosely most of the time in a stitch and hence, takes away the heat. In the meantime, the thread is also a heat source when it is in tension and hence rubbing against the needle eye. It was observed that such an action might
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raise the needle temperature by about 48C (Liasi et al., 1996). In Cox et al., 1999), a monitoring device that can detect sewing problems such as broken thread and skipping thread is reported. In summary, it has been found that: . Sewing speed is the most important factor that affects the needle temperature, though it has little effect on needle penetrating force. . Radiation plays a minor role in needle heat dissipation and hence can be ignored. . Among various needle characteristics (including the needle finish, needle point shape, needle type, etc.), the needle finish has significant effect on steady-state temperature, though the effect of needle point shape is minor. . Fabric properties (including fabric structure, fabric finish, fabric composition) have significant effects on the steady state temperature of the needle: the heat generated by the friction contact between the needle and the fabrics is primarily a function of fabric-surface frictional characteristics and fabric tightness. The thickness of the fabric is also very important. . Properly installed cooling systems can increase convection and, hence, reduce needle heating. These findings are used in developing the analytical models presented below. In addition, in order to simply the model, two assumptions are made: First, it is assumed that the fabrics have a uniform material property. Second, it is assumed that the needle speed is a constant. In practice, many sewing operations involve different materials and the sewing speeds vary. However, it is expected that the presented models are still valid with small modifications. 3. The sliding contact model 3.1 The basic theory The sliding contact model is developed based on a classical thermal dynamics study by Jaeger (1942). Consider an infinite solid with initial temperature zero, the temperature rise of a point (x, y, z) at time t owing to the heat source at another point (x0 , y0 , z0 ) with amount of the heat q is as follows: ! q
x ÿ x0 2
y ÿ y0 2
z ÿ z0 2 T
2 exp ÿ 4 t 8k
t3=2 where, = (k/c), k is the material thermal conductivity, is the material density and c is the specific heat. Now suppose the heat source is moving along the Z-axis. Replace the heat q by qdz and integrate, it follows that the temperature rise in the solid is: ! q
x ÿ x0 2
y ÿ y0 2
3 exp ÿ T 4 t 4kt
Now let us consider the model illustrated in Figure 3 (Holm, 1948). As the Needle heating in moving solid is sliding against the stationary solid, heat is generated due to the heavy industrial friction contact between the two solids. Consequently, temperature is developed sewing and the heat permeates into the bodies of both solids. Assuming that the: . stationary solid is a rectangular bar with infinite length; . moving solid is an infinite plane and moves with a constant velocity of V; 93 . contact between the two solids is 2l in both X and Y directions; and . initial temperature is zero in both the stationary solid and the moving solid. Then, the temperature rise in the stationary solid can be found by integration: ! Z l Z l Z1 q
x ÿ x0 Vt2
y ÿ y0 Vt2 z2 dt 0 0 T exp ÿ dx dy 4 t 4k t ÿl ÿl 0
4 h Zl Zl 1 i q V 0 0 2 2 dx0 dy0 eÿV
xÿx ÿ
yÿy =2 K0
x ÿ x0
y ÿ y0 z2 k 2 ÿl ÿl
where K0() is the modified zero order Bessel function of the second kind. To solve equation (4), introducing the dimensionless quantities: Vx Vy Vz X ;Y ;Z
5a 2 2 2 and parameters: x ÿ x0 ; y ÿ y0
5b
Then, it follows that:
Figure 3. Illustration of the sliding contact model
n ÿ o XL Y L 2 2 2 1=2 Z Z exp ÿ Z q T eÿ dd 1=2 kV
2 2 Z 2
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6
Y ÿL
where, L is a dimensionless quantity defined below:
94
L
Vl 2
By integrating, it can be shown that at z = 0, the temperature rise is: q T I
X L ÿ I
X ÿ L I
Y L ÿ I
Y ÿ L 4kV
7
8
where: Zx I
x
eÿu K0
jujdu
9a
0
Zx I
ÿx ÿ
eu K0
jujdu
9b
0
Based on equation (6), it can be shown (Holm, 1948) that for small L (say L < 0.1), the maximum temperature is: p 8q L ql loge 1 2 1:122
10 Tmax kt k and the average temperature is: ( ) p p 8 qL ql 2ÿ1 loge 1 2 ÿ 0:946 Tavg kV k 3 On the other hand, for large L (say L > 5), the maximum temperature is: 4q L1=2 2q 2 l 1=2 Tmax k V kV 1=2
11
12
and the average temperature is: Tavg
8q L1=2 1:064q l 1=2 k V 3kV 1=2
13
For intermediate values of L (i.e. 0.1 < L < 5), the temperature rise an be obtained by interpolation.
3.2 The sliding contact model for needle heating Needle heating in Using the sliding contact theory presented above, the sliding contact model for heavy industrial needle heating is developed. First, it is noted that the diameter of the needle is sewing small (about 1mm). In comparison, the needle is very long (over 20mm). Hence, the needle can be considered as a solid bar with infinite length. Second, it is obvious that the fabric can be considered as an infinite plane. Finally, it is 95 assumed that within one stitch, the sliding contact between the needle and the fabric generates a constant heat source. Under these assumptions, if both the fabric and the needle are perfect insulators, then the theory above can be directly applied. Nevertheless, since they are not perfect insulators, adjustment must be made. To compensate the effect of heat exchange between the needle and the fabric, it is assumed that within a stitch both the needle and the fabric are insulators and hence, their temperatures can be calculated independently. This assumption is based on the fact that the sewing speed is high (over 1,000 stitches per minute) and hence, the contact conduction between the needle and the fabric would not have enough time to impose a significant effect. Consequently, it can be ignored. However, the amount of heat generated during the sliding contact between the needle and the fabric is divided as it heats both the needle and the fabric. To take this into consideration, the heat partition ratio, , is introduced. Suppose a total amount of heat, q, is generated, then a fraction of the heat goes to heat the needle and the remaining fraction (1 ± ) goes to heat the fabric. With this compensation, the temperatures of the needle and the fabric can be calculated using the sliding contact theory presented above. Suppose the fabric thickness is = 2mm, and the sewing speed is V = 1,000rpm. For the needle, the sliding contact can be considered as a heat source with l = 2, or L 200. Hence, its average temperature, T1, can be determined by equation (13), i.e.:
q 1 l 1=2 T1 T01 1:064
14 k1 V where, T01 is the initial temperature, 1 = (k1/1c1) and k1 are the thermal characteristics of the needle. On the other hand, for the fabric, L is small because the material density and specific heat are small. Hence, its average temperature can be determined using equation (11), i.e.: T2 T02 0:946
1 ÿ ql k2
15
where, T02 is the initial temperature, 2 = (k2/2c2) and k2 are the thermal characteristics of the fabric. Note that the temperature difference between the needle and fabric makes the heat exchange achieve the same temperature. Hence, there shall be T1 = T2. Consequently, the heat partition ratio is:
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96
0:946ql ÿ
T01 ÿ T02 k2
q 1 l 1=2 0:946ql 1:064 k1 V k2
16
From equation (16), it is seen that the heat partition ratio is a function of material properties of the needle and the fabric, the sewing speed, the fabric thickness, and the initial temperature difference between the needle and the fabric. In particular, the higher the sewing speed, the bigger the . It should be noted that the heat partition ratio is not a constant even within a stitch since the temperatures of the needle and fabric change continuously. Equation (16) is an approximation by averaging. It is interesting to know that the heat partition also reflects the heat conduction from the needle to the fabric, which is in the term (T01 ± T02). Within a stitch, following the heating period is the cooling period. As the needle withdraws from the fabric, the friction heating ends and both the needle and the fabric begin to cool down because of the convection. At this time, the needle and the fabric are independent and their temperature decreases can be determined using the basic thermal dynamic equation (this will be further discussed in next section): hF t
17 T T1
Ti ÿ T1 exp ÿ cW where, T1 is the environment temperature, Ti is the initial temperature at which the cooling begins, hc is the convection coefficient, F is the cooling surface area, and W is the cooling volume. Note that for both the needle and the fabric, while F can be estimated rather accurately, W is difficult to find. Hence, a coefficient is used to adjust the cooling volume. For example, suppose the volume of the needle is W. However, as pointed out earlier, the heat only penetrates a small depth from the surface. So, the actual cooling volume is W, where 0.01. The above calculation is repeated stitch by stitch for the entire sewing operation. For the first several stitches, it is noted that the fabric is heated by the sliding contact and cooled by convection, while the needle is heated by both the sliding contact and the conduction of the fabric. In the subsequent stitches, the needle temperature increases. The fabric is still heated both by the sliding contact and the conduction of the needle, while the needle is heated by the sliding contact but cooled by the fabric. Typically, after some 30~50 stitches, the needle temperature will reach a steady state. In summary, the procedure to calculate the needle heating is given in Table I. 3.3 Simulation results A number of simulations were conducted at different sewing speeds and different fabric thicknesses. Figure 4 shows several typical temperature
responses obtained at sewing speed of 2,000rpm, 1,000rpm and 500rpm with Needle heating in the fabric thickness of 4mm. The time constants (defined as the time period heavy industrial needed to achieve the 63.2 per cent of the steady state value) are also shown in sewing the figure. The simulation results were validated by the experiment, which will be further discussed in Part 2 of our study. Figure 5 summarizes the simulation results showing the needle temperature 97 obtained at different speeds (1,000rpm to 3,000rpm) and different fabric thicknesses (2mm to 8mm or one ply to four ply). It is found that when fabric thickness is about 2mm to 6mm, and sewing speed is within 2,000rpm, simulation results match the experiment results well (refer to Part 2 of our study). However, when sewing conditions exceed this range, the simulation model usually gives a higher temperature than that from the experiment. This read the needle parameters (k1 ; 1 ; F1 ; W1 ; ) read the fabric parameters (k2 ; 2 ; F2 ; W2 ) read the contact length (l) read the sewing parameter (V) read the initial temperature (T10 ; T20 ) for i = 1 to number_of_stitches do calculate the heat partition ratio using equation (16) calculate the needle temperatures using equations (12) and (13) calculate the fabric temperatures using equations (10) and (11) calculate the needle and the fabric cooling using equation (17) end
Table I. The procedure of the sliding contact model for needle heating
Figure 4. Examples of needle temperature rise
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98 Figure 5. Peak temperature prediction using the sliding contact model
may be attributed to the fact that in the model the needle is considered as an integrated solid without conduction heat lost. Hence, the model tends to over estimate the temperature, especially when the sewing speed is high. This motivates the development of the lumped variable model presented in the next section. 4. The lumped variable model 4.1 The basic theory It is known that when a solid receives sudden heating or cooling, its temperature distribution will change depending on its thermal conductivity and its surface heat transfer coefficient. If its thermal conductivity is large and its surface heat transfer coefficient is small, then its internal temperature gradient will be small and hence, the entire solid will reach the same temperature in a short time. In this case, the so-called lumped variable model can be applied (Arpaci, 1966). The lumped variable model is relatively simple. Given an arbitrary solid with volume W and surface area F. Suppose it has a uniform initial temperature T0 and will receive a constant heat Q at time zero. Furthermore, suppose the solid is surrounded by the heat source and there is no heat loss through convection or radiation. Then, since all the heat is absorbed to increase the internal energy of the solid, the following equation applies: Q cW
dT ; t 0 and T T0 dt
18
where, is the material density and c is the specific heat. The solution of equation (18) is as follows: T T0
Q t cW
19
Now suppose at t = t0, T = T1, the solid is exposed in the environment with temperature T1 to cool down (T1 > T1 ) and the convection coefficient is h.
Since the convection heat loss results from the reduction of the internal energy Needle heating in of the solid, the following equation applies: heavy industrial dT sewing
20 ÿhF
T ÿ T1 ; t t0 ; T T1 cW dt The solution to equation (20) is as follows:
hF T T1
T1 ÿ T1 exp ÿ t cW
99
21
This is the same as equation (17) presented in section 3. In practice, whether the lumped variable model can be applied is dependent on the geometry and thermal property of the solid. Rewrite the exponential term in equation (21) as follows: hF hW kF 2 h
W =F t t Bi Fo t 2 cW kF cW k
W =F2
22
where, k is the thermal conductivity, Fo is the Fourier number representing the dimensionless time and Bi is the Biot number representing the ratio of inner thermal resistance to the external thermal resistance. Following the study by Holm (1948), Bi can be used to determine whether the lumped variable method is applicable. First, introduce a non-dimensionless number M; for infinite plate M = 1; for infinite cylinder M = 1/2; and for infinite sphere M = 1/3. If: Bi
h
W =F < 0:1M k
23
Then, the temperature difference within the solid will be less than 5 per cent and, hence, can be ignored. Consequently, the lumped variable can be applied. Consider the needle as an infinite cylinder with a diameter r, it follows that: Bi
h
W =F r h k 2k
24
Since the diameter of the needle is small, with typical needle material Bi << 0.1*(1/2) = 0.05. Therefore, the lumped variable model can be applied. The lumped variable model can be used to predict the temperature distribution of a solid as well. Consider a hemisphere with the radius r0 as shown in Figure 6. The hemisphere may be regarded as a concentric isotherm. Suppose that from the time t = 0 on, a constant heat Q is applied to the hemisphere uniformly. In addition, there is no heat lost to the environment. Then, the thermal dynamic equation of the hemisphere is as follows (Holm, 1948): @ 2 T 2 @T c @T 2 @r r @r k @t
25
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Initial condition: t 0; T 0; Boundary condition:
@T ; r r0 ; t > 0 Q ÿ2b k @r 2
100
It can be shown that at the surface of the hemisphere, the temperature rise is as follows: h io Q n 0 1=2
26 1 ÿ et 1 ÿ
t 0 T
ro ; t0 2kr0 where: k t cr02
t0
t0
2
Zt0
1=2
27a
2
eÿ d
27b
0
In particular, let t ! 1, the steady-state temperature is found: Q T
r0 ; 1 2kr0
28
4.2 The lumped variable model for needle heating In order to use the lumped variable model, the continuous sliding motion between the needle and the fabric is modeled by a series of discrete motions representing the fabric sliding against the needle section by section. Each section has the same length as the fabric thickness as shown in Figure 7. The time during which the friction heating is generated is t = /V, where is the
Figure 6. The lumped variable model of a hemisphere with a radius b
fabric thickness and V is the sewing speed. In each section, the temperature rise Needle heating in in the needle is calculated based on equation (19). When the section is not in heavy industrial contact with the fabric, it cools down and the temperature decrease is sewing calculated using equation (21). Similar to the sliding contact model, the heat partition ratio between the needle and the fabric is very important. Consider a given section of the needle. 101 First, since the size of a section is small, during the heating period (i.e. when it is in contact with the fabric) the conduction heat loss can be ignored. Assuming that a total amount of heat Q is generated, the needle will absorb a portion Q, and the fabric will absorb the rest (1 ± )Q. According to equation (19), the temperature rise of the needle will be:
Q t
29 T1 T01 cW1 where W1 is the volume of the section. The calculation of the temperature rise of the fabric is somewhat complicated as the sections of the needle heat the same fabric again and again. Assume there is no heat loss from the fabric surfaces that are not in contact with the needle. Then, the temperature rise can be calculated using equation (27). However, equation (27) is derived for a hemisphere, while the contact between the needle and the fabric is a cylinder. Hence, an adjustment must be made. The adjustment is based on two considerations. First, the surface area of the cylinder shall be equal to the area of the hemisphere. Second, the temperature rise in the cylinder and the temperature rise in the hemisphere shall follow a similar pattern. Consequently, a coefficient, , is introduced to adjust the shape transformation from the hemisphere to the cylinder. That is:
It follows that:
2r02
2r
30
p r0 r
31
Note that the coefficient can be determined based on experiment. Based on our study, 1.4. From equation (27), the temperature rise of the fabric is:
Figure 7. Illustration of the lumped variable model for needle heating
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T2 T02 where:
102
1 ÿ Q
t 2k2 r0
n h i 0
t 1 ÿ et 1
t 1=2
32
33
Furthermore, let T1 = T2, the heat partition ratio is as follows:
t T01 ÿ T02 ÿ Q 2k b
2 t
t 1 c1 Vol 2k2 b
34
Suppose the needle moves with a uniform speed V, then: Q fV ; t =V ;
35
where, f is the friction force and its calculation can be found in Mallet and Du (1998). Equation (34) becomes:
=V T01 ÿ T02 ÿ f V 2k2 b
=V
=V 1 c1 Vol 2k2 b
36
In summary, the procedure for calculating the needle heating is as in Table II. 4.3 Simulation results A number of simulations were conducted with different sewing speeds and fabric thickness. Figure 8 shows several examples of temperature rise obtained at sewing speed 2,000rpm, 1,000rpm, and 500rpm with fabric thickness of 4mm. In comparison to Figure 4, the temperature variation is much smaller. This may be attributed to the fact that in the lumped variable model, the needle heating is modeled as heating section by section. Figure 9 summarizes the average peak temperature of the needle obtained under different sewing speeds (ranging from 1,000 to 3,000rpm) and fabric thickness (ranging from 2mm to 8mm or one ply to four ply). When fabric thickness is about 2mm~6 mm and sewing speed is less than 2,000rpm, the simulation results match the experimental results well, as shown in Part 2 of our study. Furthermore, the simulation results are more accurate compared with that of the sliding contact model as shown in Figure 4. However, similar to the sliding contact model, when sewing conditions exceed this range, the simulation results are higher than those from the experiments. This may be attributed to the fact that the heat lose owing to the conduction along the needle is not considered. Hence, when the needle
read the needle parameters (1 ; c1 ; h1 ; F1 ; W1 ) read the fabric parameters (k2 ; 2 ; F2 ; W2 ; ) read the friction force (f) read the needle speed (V) read the initial temperature (T10 ; T20 for i = 1 to number_of_stitches do for j = 1 to number_of_sections do if the section is in contact with the needle then calculate the heat partition ratio using equation (36) calculate the needle temperatures using equation (29) calculate the fabric temperatures using equation (32) else do calculate the needle and the fabric cooling using equation (21) endif end end
Needle heating in heavy industrial sewing 103
Table II. The procedure of the lumped variable model for needle heating
Figure 8. Simulation examples using the lumped variables model
temperature is high, its influence becomes significant, resulting in additional errors. 5. Conclusions This is Part 1 of our study on needle heating in heavy industrial sewing. It presents two analytical models: the sliding contact model and the lumped variable model. In general, the needle heating problem is a complicated unsteady heat transfer problem. Such a problem may be simplified in three
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104 Figure 9. Needle peak temperatures obtained from the lumped variable model
ways: the geometry of the object, the boundary conditions, and the thermal characteristics of the object. In the sliding contact model, the needle is simplified as an infinite rectangular bar and the fabric is modeled as an infinite plane. The sewing operation is modeled as the plane slides against the bar without conduction heat lost. This model is relative simple and works well when the sewing speed is relatively low (< 2,000rpm) and the fabric is relatively thin (< 6mm). In the lumped variable model, the needle is divided into a number of sections. The sewing operation is modeled as the needle slides against the fabric section by section. Again, it is assumed that there is no conduction heat lost. The lumped variable model is usually more accurate than the sliding contact model as it models the contact between the needle and the fabrics more accurately. However, its accuracy is limited when the sewing speed passes 3,000rpm. Both the sliding contact model and the lumped variable do not require extensive computation. As a result, they can be used to estimate the needle temperature in shop floor and provide valuable information in optimizing industrial sewing operations. References Arpaci, V.S. (1966), Conduction Heat Transfer, Addison-Wesley Publishing, Reading, MA. Cox, R.N., Titus, K.J. and Clapp, T.G. (1999), ``An on-line monitoring system to recognize stitch defects through thread motion and high speed image analysis'', Trans. of ASME, J. of Manufacturing Science and Engineering, Vol. 121, February, pp. 104-8. Hersh, S.P. and Grady, P.L. (1969), ``Needle heating during high-speed sewing'', Textile Research Journal, Vol. 39, pp. 101-20. Holm, R. (1948), ``Calculation of the temperature development in a contact heated in the contact surface, and application to the problem of the temperature rise in a sliding contact'', Journal of Applied Physics, Vol. 19, pp. 361-6. Howard, G.M. and Parsons, D. (1968), ``Sewing needle temperature, part I: theoretical analysis and experimental methods'', Textile Research Journal, Vol. 38, pp. 606-14. Howard, G.M., Sheehan, J.J., Mack, E.R. and Virgilio, D.R. (1971), ``Sewing needle temperature, part II: the effects of needle characteristics'', Textile Research Journal, Vol. 41, pp. 231-8.
Hurt, F.N. and Tyler, D.J. (1972), ``An investigation into needle heating and associated problems in machine sewing III'', Hatra Research and Report, No. 21, September. Jaeger, J.C. (1942), ``Moving sources of heat and the temperature at sliding contacts'', Proceedings of Royal Society NSW, Vol. 76, pp. 203-24. Liasi, E. et al. (1999), ``Heating of an industrial sewing machine needle'', accepted for publication by Int. J. of Clothing Science and Technology. Mallet, E. and Du, R. (1998), ``Finite element analysis of sewing processes'', International Journal of Clothing Science and Technology, Vol. 11 No. 1, pp. 19-36. Najafi, M., Smith, S.A. and Ye, H. (1994), ``Investigation of the temperature distribution in sewing machine needles'', Proceeding of the Fifth Annual Academic Apparel Research Conference. Perry, J.H. (Ed.) (1963), Chemical Engineers' Handbook, 4th ed., McGraw-Hill, New York, NY. Simmons, S. and Keller, A.Z. (1980), ``A physical model of needle heating'', Clothing Research Journal, Vol. 2, pp. 37-46. Stylios, G. and Xu, Y.M. (1995), ``An investigation of the penetration force profile of the sewing machine needle point'', Journal of the Textile Institute, Vol. 86, pp. 48-163.
Needle heating in heavy industrial sewing 105
The current issue and full text archive of this journal is available at http://www.emerald-library.com/ft
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106 Received September 1999 Revised January 2001 Accepted January 2001
Total handle evaluation from selected mechanical properties of knitted fabrics using neural network Shin-Woong Park, Young-Gu Hwang and Bok-Choon Kang Department of Textile Engineering, Inha University, South Korea, and
Seong-Won Yeo
Department of Electrical Engineering, Inha University, South Korea Keywords Mechanical properties, Fuzzy logic, Neural networks, Knitwear, Simulation Abstract This paper concentrated on the objective evaluation of total hand value in knitted fabrics using the theory of neural networks and the comparison of two methods. For the objective evaluation of overall hand feeling in knitted fabric, 47 kinds of weft-knitted and warp-knitted fabrics were manufactured. The optimum construction of neural networks was investigated through the change of layer and neuron number. For the comparison of the two methods, a subjective test was carried out. Two techniques, KES-FB system and neural network applied simulator, were compared using nine randomly selected knitted fabrics. These fabrics were used to show that the neural network adapted simulation method was in good agreement with subjective test results.
International Journal of Clothing Science and Technology, Vol. 13 No. 2, 2001, pp. 106-114. # MCB University Press, 0955-6222
1. Introduction Fabric hand has been considered as one of the most important performance attributes of textiles intended for use in garments. Methods for predicting knitted fabrics in apparel manufacture from its physical, mechanical and dimensional properties have been investigated (Kawabata, 1980; Gong, 1995; Park and Hwang, 1999). In previous papers (Park and Hwang, 1999; Park et al., 1996; 1997; 1998), we have published data regarding fuzzy predicting model of woven, warp-knitted and double weft-knitted fabrics and have studied a fuzzy applied method and a neural network applied simulation. A subjective test gave a good agreement with results of the fuzzy model and the neural network prediction simulator rather than that of KES-FB system. But fuzzy method is not a simulator, but a mathematical modeling equation. We have investigated the neural network applied total handle evaluator, which is a method setting fuzzy mathematical results as a target output. Therefore, it was recognized that there is a need to establish an exact automatically hand evaluation system, being based on subjective test results. In this paper, we extend our investigations to the objective hand evaluation of knitted fabrics used for fall and winter, which included various type of fibers and their constructions of single, double and warp-knitted fabrics. The authors wish to thank the Inha University and Industrial Technology Research Institute Foundation for the financial support provided for this study.
2. Experiment 2.1 Neural networks Neural networks are models for computational automatic systems, either in hardware or in software, which imitate the behavior of biological human neurons by using a large number of structurally interconnected artificial neurons. A neuron passes information from its inputs to the output (leading to other neurons) obeying a certain transfer function (sigmoid function, see in Figure 1). This consists of two consecutive stages: one is adding up the information from the input data, whereby, each input will be attenuated by the biochemical binding, and two is deciding if and how it will be transferred to the output value. Neural network is a good mimic of the biological neuron, and maps the biological parts to a mathematical model: the neucleus becomes a processing element and input weights, and adding up the N inputs becomes a linear mathematical operation. Figure 2 illustrates a two layer feed-forward network. The notational conventions are shown in the figure; output units are denoted by Oi, hidden units by Vj, and input terminals by k.
Mechanical properties of knitted fabrics 107
Figure 1. A continuous sigmoid transfer function
Figure 2. A two-layer feed-forward network, showing the notation for units and weights
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Given pattern , hidden unit j receives a net input: X wjk k hj
1
k
and produces output:
X wjk k : Vj g
108
2
k
Output unit i thus receives: X X X Wij Vj Wij g
wjk k hi
3
and produces for the final output: X X X Wij Vj g
Wij g
wjk k Oi g
hi g
4
j
j
j
k
j
k
where wjk is the weight coefficient from inputs to hidden units, and Wij from the hidden units to the output units. The index i refers to an output unit, j to a hidden one, and k to an input terminal. We label different patterns by a superscript , so input k is set to k when pattern is being presented. The k 's can be binary (0/1, or 1) or continuous-valued. We used N for the number of input units and p, for the number of input patterns ( = 1, 2, 3, . . . p). 2.2 Sample preparation We produced or collected 47 samples of knitted fabrics, which consisted of single, double weft-knitted and two-bar or three-bar pattern warp-knitted fabrics. These fabrics are commercially available within their class and have been produced by knitting machine. The range of mechanical properties in the samples was from summer end-use to winter. Fabric mechanical properties such as tensile, bending, shearing, compression and surface are measured by the KES-FB system under the condition of standard. From the 17 measured mechanical properties, which are from the major characteristics of six mechanical properties groups, seven mechanical properties (e.g. maximum tensile elongation, the recovery of tensile and compression, bending rigidity, shear hysteresis, surface roughness, weight) stemming from four possible deformation modes (tensile, compression, bending, and shear properties) were selected and two physical properties (weight and surface properties) (Kawabata, 1980; Gong, 1995; Park and Hwang, 1999; Park et al., 1998). The sample data for the experimental knitted fabrics are given in Table I. In earlier papers (Park et al., 1995; 1996; 1997; 1998), we built a simple and reliable fuzzy total handle predicting model which consists of three fuzzy applied membership functions and six weighted factor vectors. But this model is just a mathematical construction, therefore, we programmed a simulation
which consists of two steps; one step is to fuzzify the mechanical properties into value (from 0 to 1), and the next step is to training input values until leading into the desired output value which is from the fuzzy applied hand value. In this research, we used two theories (fuzzy and neural networks) and did not apply subjective results. Therefore, it is recognized that we had better construct a more applicable simulator using the back-propagation algorithm in neural networks (see in Figure 3), which puts the subjective results as target outputs. Figure 3 shows the back-propagation algorithm in the three layer neural networks, where 1 and 2 represent input units and 1, 2 and 3 are the backpropagation of errors.
Mechanical properties of knitted fabrics 109
2.3 Neural networks system using subjective evaluation results as an output The panel of evaluators included 30 Inha University students, who belong to the department of textile engineering. The test fabrics are presented to individual evaluators, they feel the samples by rubbing and squeezing them in their hands and then ranked them for overall hand preference. Evaluators are instructed to judge all fabrics for fall or winter outerwear knit leveling 0 to 5. This provided data that can more easily verify the feasibility of our total hand evaluation approach. Therefore, we constructed a typical multi-layered neural network: . The number of inputs is seven mechanical properties (tensile recovery (RT), maximum tensile elongation (EMT), compressional recovery (RC), bending rigidity (B), shear hysteresis of 0.58 (2HG), surface roughness (SMD) and weight (W)). Fabric construction Single weft knit Double weft knit 2, 3, 4-bar warp knitted fabrics
Yarn material and construction
Number of samples
Thickness (mm)
Weight (mg/cm2)
Wool (spun) Cotton (spun), polyester (filament) Polyester, nylon, spandex (filament)
12
2.11-2.68
18.03-32.86
14
0.87-2.09
8.60-30.55
21
0.38-2.07
4.62-7.62
Table I. The experimental fabric groups
Figure 3. Back-propagation in three-layer network
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. . .
110
Two hidden layers; an optimum structure of this simulator (see Figure 4). One output; total hand value as a overall hand feeling value. Sigmoid function was used to make more suitable for analytical study (see Figure 1).
2.4 Evaluation of total hand value Using the constructed neural network simulator, we could evaluate the total value of arbitrary sample knit fabrics. Tables II and III show the summary statistics for mechanical properties of training set and testing set. We measured the mechanical properties and calculated total hand value of 47 kinds of knit fabrics with the KES-FB instrument, all the data fed into the back-propagation of the neural network with subjective results from 30 judges. The mechanical properties and total hand value of nine unknown knitted fabrics were measured using the KES-FB system and also surveyed by the same panel of 30 judges. The selected seven mechanical properties of 47 knitted fabrics were put into the input layer and total hand value calculated.
Figure 4. The optimum architecture of neural networks
Table II. Summary statistics for mechanical properties of training set
Mechanical properties
Mean
Standard deviation
Minimum value
Maximum value
Compressional recovery (RC) Tensile recovery (RT) Maximum elongation (EMT) Shear hysteresis (2HG) Bending rigidity (B) Surface roughness (SMD) Weight (W)
50.04 45.10 32.48 2.43 0.07 7.57 22.74
13.3304 13.2739 27.5435 1.1667 0.0691 4.0487 6.5475
32.89 25.13 4.51 0.75 0.01 2.93 8.60
84.51 62.45 98.76 6.12 0.16 13.19 32.86
2.5 Procedure and calculation of the total hand value There are several ways neural network can go through the training phase. The back-propagation method is an example of an architecture where all weights are adapted at each learning cycle (see Table IV). The training set process of our neural network is as follows: (1) Put all the seven selected mechanical properties that are from 47 kinds of knitted fabrics into the neural network.
Mechanical properties
Mean
Standard deviation
Minimum value
Maximum value
Compressional recovery (RC) Tensile recovery (RT) Maximum elongation (EMT) Shear hysteresis (2HG) Bending rigidity (B) Surface roughness (SMD) Weight (W)
52.51 45.30 39.16 2.57 0.065 8.07 22.03
15.8718 16.9823 35.8238 1.8511 0.0339 4.1179 6.1755
42.54 23.65 4.51 1.24 0.02 2.36 12.15
84.51 65.09 95.13 6.12 0.12 12.63 29.73
Neuron no. 1
2
3
4
5
6
Weight of hidden layer First layer Second layer 0.0923 0.0075 0.0512 0.0058 ±0.0078 ±0.0097 ±0.0408 0.0972 0.0891 ±0.1102 ±0.0412 0.0919 0.0844 ±0.0356 ±0.0031 0.1553 0.0361 ±0.0191 0.0227 ±0.0151 0.0324 0.0080 0.0554 ±0.1551
±0.0402 0.0068 ±0.0218 0.0972 0.0026 0.1857 0.0378 ±0.0452 ±0.0227 ±0.1206 ±0.1351 ±0.0514
0.0136 ±0.0412 0.1088 ±0.0232 0.0522 0.0565 0.0487 ±0.0927 0.0297 0.1823 ±0.1221 ±0.1385 ±0.0183 0.1654 ±0.1635 ±0.2807
0.0421 ±0.0820
Mechanical properties of knitted fabrics 111
Table III. Summary statistics of mechanical properties of testing set
Output layer ±0.1442 0.1062 0.3900 0.7388
±0.0676 0.0329 ±0.0167 0.0458 0.0994 0.2810
±0.0674 0.0032 0.0881 0.0222 0.0510 0.1136
Table IV. The weights of neurons in the optimum neural network construction
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112
(2) Test training set with changing hidden layers and their neurons. (3) Adjust the weight of the network system in a way that minimizes the error. (4) Calculate the error between the network output and the desired output (the target output from subjective survey test results). (5) Repeat steps (1) through (3) for each total hand value (THV) in the training set until the error for the entire set is acceptably low. To obtain the weights of optimum artificial neural network system, we trained with a changing number of hidden layers and neurons and minimizing error rating. The total handle evaluating process was performed as follows: (1) Assign all connection weights according to the trained results. (2) Selected one unknown sample mechanical properties to the neural networks. (3) Compute the data of output value. 3. Results and discussion 3.1 Optimal construction of total hand simulator The configuration of adopted architecture of the neural network for knit fabric overall hand evaluation was shown in Figure 4. So we developed the optimum structure of the total hand value simulator system: the number of input neuron nodes is set to seven, which is equal to the number of input features and the output node is one, and hidden layer is two which is an important element because it is related with the speed and summing error of the other formation. The increment of layer gives a bad effect on the speed which reaches the minimum error. As we increase the hidden layer to more than three, the error value of neural networks does not decrease less than 0.5, and then to the time of training was longer than the two hidden layer construction. And moreover, when we set the one hidden layer, the difference between desired output and calculated values is higher than the two hidden layer structure. With the change of neuron, the training time is similar but generally 7-6-4-1 formation was a good agreement with target output. Therefore we could summarized the optimum construction in Figure 4. 3.2 Comparison of total hand value of neural networks and KES-FB with subjective test Using the results from the subjective trial, we can compare and verify which method is a good agreement with the subjective test: neural networks and KESFB system (see Figure 5). The weighted values of optimum artificial intelligent construction were determined (see Table IV). From this investigation, it was found that the results of subjective assessment were more consistent with neural networks rather than the KES-FB method (see in Figure 5). As a matter
Mechanical properties of knitted fabrics 113 Figure 5. Comparison of the results with three methods (THV of KES-FB, neural network and subjective test)
of fact, fabric handle in a country can be expressed well by panels who have a similar cultural background and circumstance, the KES-FB system was developed by the Japanese and the environment of Japan is different from Korea or other countries. Moreover, most of the sample fabrics were weftknitted fabrics and were produced 20 years ago. Now there are many kinds of newly developed materials, yarns and various knitted fabrics. Therefore, is the best fabric which might be evaluated differently on the basis of human feeling, geographical area, time and so on. 4. Conclusions It has been indicated that the technique of neural networks by means of backpropagation showed better agreement with the subjective test method than KES-FB system. Our neural networks method revealed a good coincidence with the results of subjective assessment. It has also been established that optimum construction of multi-neural networks was shown in Figure 4. Another advantage of our automatic THV evaluator is that it is simple in application, and is applicable for a different textile market or an area if surveyed and for a fabric type. Therefore it can be stated that the neural network approach provides an effective skill for overall hand feeling of outerwear knitted fabric and woven fabric. References and further reading Gong, R.H. (1995), ``Quality measurement of knitted apparel fabrics'', Textile Res. J., Vol. 65, p. 5449. Hertz, J.A., Palmer, R.G. and Krogh, A.S. (1991), Introduction to the Theory of Neural Computation, Vol. 1, Addison-Wesley Publishing, Reading, MA. Kawabata, S. (1980), The Standardization and Analysis of Hand Evaluation, 2nd ed., HESC, Text. Mach. Soc., Japan.
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Park, S.-W. and Hwang, Y.-G., (1999), ``Measuring and fuzzy predicting total handle from selected mechanical properties of double weft-knitted fabrics'', Textile Res. J., Vol. 69, pp. 19-24. Park, S.-W., Hwang, Y.-G. and Kang, B.C. (1997), ``A fuzzy application to fabrics hand evaluation (II): application to polyester fabrics in Korea'', J. Korean Fiber Soc., Vol. 34, pp. 85-9. Park, S.-W., Hwang, Y.-G., Kang, B.C. and An, J.S. (1995), ``Studies on the mechanical properties and hand of double knitted fabrics'', J. Korean Fiber Soc., Vol. 32, pp. 859-68. Park, S.-W., Hwang, Y.-G., Kang, B.C. and Cho, H.H. (1996), ``A fuzzy application to fabrics hand evaluation (I): application to double weft-knitted fabrics'', J. Korean Fiber Soc., Vol. 33, pp. 849-54. Park, S.-W., Hwang, Y.-G., Kang, B.C., Bae, C.K. and Choo, K. (1998), ``A fuzzy application to fabrics hand evaluation (III): application to warp-knitted fabrics'', J. Korean Fiber Soc., Vol. 35, pp. 119-24. Raheel, M. and Liu, J. (1991), ``An empirical model for fabric hand. Part I: objective assessment of lightweight fabrics'', Textile Res. J., Vol. 61, pp. 31-8.
The current issue and full text archive of this journal is available at http://www.emerald-library.com/ft
A hybrid flowshop scheduling model for apparel manufacture
Hybrid flowshop scheduling model
Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong, and
Received April 2000 Revised January 2001 Accepted January 2001
W.K. Wong and C.K. Chan W.H. Ip
115
Department of Manufacturing Engineering, The Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong Keywords Scheduling, Genetic algorithms, Apparel manufacturing Abstract A hybrid flowshop (HFS) problem on the pre-sewing operations and a master production scheduling (MPS) problem of apparel manufacture are solved by a proposed two-tier scheduling model. The first objective of this paper is to plan a MPS for the factory so that the costs are minimized when the production orders are completed before and after the delivery dates required by the customers. The second objective is to minimize the completion time of the pre-sewing operations in the cutting department while the production quantities required by the sewing department at several predetermined times can be fulfilled by the cutting department. Experimentation is conducted and the results show the excellent performance of the proposed scheduling model for the apparel industry.
1. Introduction In many manufacturing systems, hybrid flowshops are always found. HFS comprises series of production stages, each of which has several machines operating in parallel. Some stages may have only one machine, but at least one stage must have multiple machines. The flow of jobs through the production floor is unidirectional. Each job is processed by one machine in each stage and it must go through one or more stages. Many researches have been conducted on the HFS scheduling problem. Hoogeveen et al. (1996) solved two identical machines in stage 1 and only one machine at stage 2 to minimize makespan in a NP-hard problem. Vignier (1996) proposed two heuristics in two cases to minimize the maximum lateness in a parallel machine problem. Gupta et al. (1997) presented a bound and bound procedure and heuristics were applied to derive an initial upper bound. Fouad et al. (1998) solved a hybrid three-stage flowshop problem in the woodworking industry by using dynamic programming-based heuristic and branch and bound-based heuristic. Linn and Zhang (1999) reviewed the current research of HFS scheduling problem from two-stage to k-stage and discussed the future direction of research. In the research of these production planning and scheduling problems, many researchers have paid much attention to the earliness and tardiness production scheduling models and their optimization. Cleveland and Smith (1989) investigated the use of genetic algorithms to schedule the release of jobs into a
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manufacturing facility, called the sector release scheduling problem. Gupta et al. (1997) applied genetic algorithms to minimize the flowtime variance of the n-job single-machine scheduling problem. Lee and Kim (1995) minimized the total weighted earliness and tardiness penalties from common due date by using genetic algorithms. Chung et al. (1991) proposed pseudo-polynomial dynamic programming algorithms to minimize weighted number of tardy jobs and E/T penalties about a common due date. Shintaro et al. (1999) applied Sahni's algorithm to a parallel machine scheduling problem to minimize maximum completion time and maximum lateness. Production schedule planning in a multi-stage manufacturing operation involves making critical decisions at different levels of management. This paper is aimed at developing a model based on the earliness and tardiness production scheduling and hybrid flowshops scheduling approach with genetic algorithms (GAs) to assist the factory management and production-floors management of the apparel manufacturing companies. The proposed approach can be used for preparation of master production schedule (MPS) and implementation of daily productionfloor schedule. 2. Statement of the problem In the apparel industry, master production schedules are always developed to meet the contract delivery dates of the buyers. In many cases, the production orders from the same buyer are grouped together on the production schedule. Those late completed orders contribute to extra transportation costs and reduced selling price of the garments demanded by the buyers to compensate the late delivery. In this paper, a model of two-tier hierarchy of garment manufacturing is developed to assist the production manager in the planning and control of manufacturing orders and production capacity. The top hierarchy, first, schedules the sequence of the production orders for the whole factory based on the minimization of the tardiness cost. Once the sequence of the production orders is scheduled, the next hierarchy of the model will optimize the operation of cutting and sewing operations under the constraint of limited spreading capacity while meeting the production quantities required by the sewing department. In the proposed model, the operations of the cutting and sewing floors are considered as the HFS scheduling problem in which the pre-sewing operations including spreading, cutting and the sewing scheduling of the apparel manufacturing companies will be integrated. In the scheduling of production orders, the fabric lays will be maximized under two criteria: (1) minimum completion time of spreading and cutting operations (2) minimum lateness of cut pieces (garments) delivered to the sewing department.
3. Brief of genetic algorithms (GAs) Hybrid flowshop Recently, some researchers successfully applied GAs to the planning and scheduling scheduling problem. Lee and Choi (1995) applied GA on single-machine model problems to produce a job sequence and then jobs were time-tabled so as to minimize the total weighted E/T costs. Lo (1997) presented the scheduling problem of a sewing line by using GA and a case-based reasoning approach. Li 117 et al. (1998) proposed a GA approach to solve the ETPSP problem with lot-size consideration and multi-process capacity balancing. Wong et al. (2000a; 2000b) developed the optimal schedule of the cutting operation in the computerized fabric-cutting system by using genetic algorithm approach to minimize the idle time of the cutting machine. Wong et al. (2000a; 2000b) also applied genetic algorithms to investigate the effect of spreading-table quantities on the spreading-table planning. The basic concept of GAs is designed to simulate processes in a natural system necessary for evolution, specifically those that follow the principle of ``survival of the fittest''. GA is a search algorithm which explores a solution space to mimic the processes in the natural evolution of a living population. They represent an intelligent exploitation of a random search within a defined search space to solve a problem. It has the property of implicit parallelism and the influence of GAs is equivalent to an extensive search of hyper planes of given space. In other words, each hyper plane value is not required to be tested directly which differs from traditional search techniques. Goldberg (1989) stated that GA is a class of local search meta-heuristics that have been also proposed for combinatorial optimization problems. The concept is to represent a feasible solution as a string of genes, i.e. chromosome, and a population of solutions is generated. The evolution of the population is under the operations of crossover and mutation. Crossover refers to the two solutions merging to derive new individuals while mutation refers to a solution perturbed by changing a gene. The operation of crossover and mutation are conducted randomly. The survival of individual is based on the evaluation of fitness of the objective function. Fitness is a measurement of the individual's suitability in the environment. A high value of fitness means that the individual is more suitable to be selected and has a better chance to survive. EÂlitist strategy is used to avoid loss of the best chromosomes' genes (Man et al., 1996). This strategy fixes the loss of the potential best member by copying the best member of each generation into the succeeding generation. Sometimes the best and the worst chromosomes will produce almost the same numbers of offspring in the next population, which causes premature convergence. In this case, the effect of natural selection is, therefore, not obvious. A linear normalization, used by Li et al. (1998), which converts the evaluations of chromosomes into fitness values, is used here to solve this problem. The idea is simply to evaluate each chromosome and assign an ordered index according to the decreasing evaluation. The evaluation value is replaced by the fitness value for determination of the selecting parents and
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individuals. The new fitness value is calculated by a constant value plus a decrement rate. The basic procedure of genetic algorithms is explained as follows: Let P(g) and C(g) be parents and offspring respectively in the existing generation g; Procedure for g: = 0; initialize population P(g); evaluate P(g); for recombine P(g) to generate C(g); evaluate C(g); select P(g + 1) from P(g) and C(g); g: = g + 1 end end 4. Mathematical model The notation used in the formulation is defined as follows: a unit earliness penalty; a unit tardiness penalty; dp due date of production order p; Cp completion time of production order p; qp number of garments of production order p; u factory production sequence; a extra transportation expenses by air; s deduction of selling price; X fabric lay; j spreading sequence j = {1, 2, . . . J}; n cutting sequence; l yardage of fabric lays; L yardage of spreading tables; Y planned number of garments required at each interval; qx numbers of garments of fabric lay; W daily production minutes; R numbers of fabric lays which are planned to be setup before starting cutting; m machine used for spreading and cutting; Xnm cutting sequence of particular spreading machine n = {1, 2, . . . L}, m = {1, 2, . . . M}; i idle time of cutting machines; number of interval per working day.
4.1 Earliness and lateness penalty Hybrid flowshop In the formulation of the scheduling problem for the apparel industry, it is scheduling assumed that all the production orders have a common due date, i.e. dp = d. In model other words, the production orders p are needed to be delivered to the buyers at that specified date, commonly known as contract delivery date. Cp is denoted as the completion time of production order p. Difference of the tardiness penalties 119 occurs among the production orders because of different styles of production orders from different customers or the same customer contributes to different values of the garments which directly influence the penalty. In the apparel industry, a unit earliness penalty is assumed to be the inventory cost and a unit tardiness penalty is the summation of extra transportation expenses by air freight a and deduction of selling price s demanded by the buyers. Let Ep and Tp represent the earliness and lateness of production order p respectively. f() is denoted as the schedule of a particular production line with the minimization of earliness and lateness penalty cost. For the whole manufacturing plant with several production lines (I, II, . . .), the schedules are derived for each production line as follows:
f
2I
Ep max
0; d ÿ Cp
1
Tp max
0; Cp ÿ d
2
R X
p
d ÿ Cp
p1
R X
p
Cp ÿ d
3
p1 R X
p ap sp
4
p1
or f
R X
p Tp p Tp :
5
p1
4.2 Hybrid flowshop problem (n/m/F//Cmax) in the cutting and sewing departments Following the standard notation, the flowshop problem in the manufacturing process can be specified as n/V, mv, F//Cmax where n is the cardinality of the set of jobs J = {1, 2, . . . n} to be scheduled without pre-emption on V stages of production process. A job consists of V stages of production process. The processing time of job i in stage v is defined as p(v, i) 0. Stages v, v = 1, . . . V comprises mv machines in parallel in which each machine processes only one job at a time. ``F'' designates that the production flow of jobs is unidirectional
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from stage 1 to stage V. Each job may be processed, on one machine at any stage. The objective is to determine the sequence of jobs so that the maximum completion time Cmax = maxi=1, . . . n(Ci) is minimal, where Ci is the completion time of job i. Earliest release date first (ERD) rule is applied on the fabric lay cutting which is to minimize the variation in the waiting times of the fabric lay on the spreading tables. In the proposed model of the cutting department, there are two stages involved in the hybrid flow shop. This two-stage hybrid flow shop involves various spreading machines at stage 1 and various cutting machine at stage 2 (m1 > 1, m2 > 1). Capacity planning is an important consideration in our model which enables the optimal utilization of the capital intensive spreading and cutting equipment of modern apparel manufacturing processes. Figure 1 shows a schematic of the spreading, cutting and sewing process of an apparel manufacturing company. In order to ensure that the cutting machine has enough fabric lays to cut at the starting period of production or no occurrence of idle time on cutting machine, a small number of fabric lays have been spread before the cutting machine starts operation. Thus: R X
i
Xn 0
6
n1
The objective function to minimize the completion time of spreading and cutting is: min f
2I
Figure 1. Schematic of the spreading, cutting and sewing process of an apparel manufacturing company
N X n1
i
Xn
7
N X
i
Xn
n1
N X M X
S
Xnm ÿ
n1 m1
N X
C
Xnÿ1
8
n1
The negative value of i(Xn) will be converted into zero once: X X C
Xnÿ1 S
Xnm < if
X
S
Xnm ÿ
X
121
C
Xnÿ1 < 0; i
Xn 0:
4.2.1 Constraint of required number of garments. It is assumed that the number of garments of the fabric lays which are processed between the time interval must meet the planned number of garments required at that interval. Hence we have when: N X
C
Xn W =
9
n1 N X
qx
Xn Y :
10
n1
4.2.2 Constraint of spreading capacity. On each spreading table, there is a limit of spreading length. Hence, the sum of the spreading length of jobs which have been set up must be smaller than or equal to the spreading length of the spreading table. We have another constraint: J X M X j1 m1
l
Xjm ÿ
N X M X
l
Xnm L:
11
n1 m1
4.2.3 Constraint of cutting sequence. As there are two cutting machines (m2 > 1) in the model, any of the cutting machines will only cut the fabric lay Xn provided by the spreading machine m which must be at least greater than the fabric lay Xn±1 prepared by spreading machine m ± 1. For example, if cutting machine m7 is now cutting fabric lay Xn prepared by spreading machine m ± 2, the cutting machine m8 can only cut that fabric lay Xn±1 which is prepared by any spreading machine from machine m3 to machine m6. mXn mXnÿ1 :
Hybrid flowshop scheduling model
12
The core of the configuration lies on two GA-based schedulers which search a valid master production schedule (MPS) during a production period, and the spreading and cutting schedule (SCS) of the whole production day (see Figure 2). The order master file (OMF) stores the information of each
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Figure 2. Configuration of an E/T and hybrid flowshop scheduling system for the pre-sewing stage of apparel industry
production, i.e. number of garments per order, standard allowed minutes (SAM) per garment, due date, and supplies this information to the GA-based MPS scheduler. The scheduler will search the optimal production schedule with the lowest earliness and lateness penalty costs. In case of more than one solution with the same penalty cost or zero penalty cost, the scheduler will choose the one with the lowest value of changeover due to different styles of production order. For each production, a value g {g = 1 . . . G} representing the corresponding style is assigned to each production order. From the production management point of view, the plant is more productive for the production operatives to work when similar styles of different production orders can be grouped together. The optimal schedule with the lowest value of style changeover ! can be obtained as follows: min f
2I
G X
pg!
13
g1
where p! pug ÿ p
uÿ1g : A spread and cut time database (SCTD) is constructed to provide the spread and cut time of each fabric lay to the GA-based SCS scheduler to search the optimal schedule based on the created MPS. The spread and cut time of each fabric lay is based on the numbers of garments drawn on the maker, the number of fabric plies spread, the perimeters of patterns of the garments, the speed of spreading machines and the speed of the cutting knife.
The quantities of cut pieces required by the sewing department can be Hybrid flowshop fulfilled and the overall E/T penalty costs and makespan of the production scheduling orders can be minimized ultimately. model 5. Case studies 5.1 E/T problem on the 1st tier of the proposed scheduling system In the apparel industry, production planners often develop the MPS to meet the delivery dates required by the customers. No systematic methods on the production planning and scheduling are used. Mostly, they simply arrange the production orders based on the priority of delivery date required by the customers without the consideration of minimization of costs involved. Very often, the inventory cost involved when those orders are completed earlier than the delivery dates is not accounted for. On the other hand, for some orders which cannot be delivered on time, they need to be delivered to the customers by air which contributes extra costs, instead of by ship. In some cases, the manufacturers even are forced by the customers to reduce the selling price of the products so as to compensate the late delivery. These ultimately lead to reduced profit and loss of reputation of the apparel manufacturers. Recently, planning and scheduling problems with earliness and tardiness (E/T) penalties have drawn much attention among researchers. This approach can be used to develop an effective MPS for production scheduling. The objective function of the earliness and tardiness production scheduling and planning (ETPSP) problem mostly integrates with the JIT philosophy. In a JIT scheduling environment, jobs that complete early must be held in finished goods inventory until their delivery date, while jobs that complete after their due dates may cause a customer to incur penalty costs. Therefore, an ideal schedule is one in which all jobs finish exactly on the assigned due dates. The following is the background of the case study in which all the data were captured from a Hong-Kong-based garment manufacturing company in China which produces men's shirts: . The production lead time is five days. . The production line works for eight hours daily. . The production line is formed with 50 workers which contributes to 24,000 working minutes/day at 100 per cent efficiency. . Ten production orders are available for processing at date zero. . The number of days available from start production date to due date is 58; all the production orders need to be delivered to the buyers on the 58th day. . Production order 5 and 6 are placed by buyer E while production order 8 and 9 are placed by buyer G. The details of the production orders of a Hong Kong-based garment manufacturing company are described in Table I.
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Table I. Details of the production orders
Production order p 1 2 3 4 5 6 7 8 9 10
Buyer
Number of garments/ order qp
Standard allowed minutes/ garment
Due date dp
A B C D E E F G G H
5,136 7,320 8,508 1,164 3,588 2,182 6,444 4,440 4,608 2,356
16.9 14.8 16.7 17.4 16.5 16.5 15.3 14.9 14.9 17.4
58th 58th 58th 58th 58th 58th 58th 58th 58th 58th
Earliness Tardiness penalty unit penalty unit 0.7 0.8 0.6 0.8 0.7 0.7 0.8 0.9 0.6 0.9
1.0 1.2 0.9 1.2 1.0 1.0 1.2 1.3 0.8 1.3
Table II shows the results of the schedules on the 1st tier of the scheduling system by using different numbers of populations setting in GA-based MPS scheduler. In the genetic procedure, the population size influences both the ultimate performance and efficiency of GAs. A large population is likely to contain representatives from a large number of hyper planes which discourages premature convergence to sub-optimal solutions. On the other hand, it requires more fitness evaluations of each generation which causes an unacceptable slow rate of convergence. In the experiment, different numbers of population were set in the scheduling system. Figures 3-8 indicate the trend of GA performance at different numbers of population. In Figure 3, though convergence could be achieved at the 6th generation with the five population setting first, the penalty cost was $70,073 which was not the minimum cost since after trying the ten population setting, the penalty cost could be reduced to $65,151 at the 114th generation, as shown in Figure 4. The penalty costs $65,115 and 64,592 were obtained at the 20 and 30 population settings in Figures 5 and 6 respectively. Figure 7 illustrates that at 40 populations with 200 generations, convergence could occur in which the optimal schedule is 4 8 5 3 6 7 2 1 with minimal penalty cost $64,422 as even at the 80 population setting of Figure 8, the penalty cost was still achieved at $64,422. Population 5 10 20 Table II. Schedules generated on 30 40 the 1st tier of the 80 scheduling system
Schedule 10 4 4 4 4 4
4 10 1 10 10 10
7 1 5 1 5 5
2 5 6 5 6 6
3 6 3 6 3 3
8 3 2 3 7 7
Penalty cost 9 8 8 8 8 8
5 9 9 9 9 9
6 7 7 2 2 2
1 2 10 7 1 1
70,073 65,151 65,115 64,592 64,422 64,422
Hybrid flowshop scheduling model 125
Figure 3. Performance with five populations
Figure 4. Performance with ten populations
5.2 HFS problem on the 2nd tier of the proposed scheduling system The background of the HFS problem can be described as follows: .
.
.
A set of n independent, single-operation fabric lay is available for processing at time zero. Spreading times for fabric lays are independent of spreading sequence and can be included in processing times. There are no machine breakdowns.
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Figure 5. Performance with 20 populations
Figure 6. Performance with 30 populations .
.
. .
.
Spreading time and cutting time per fabric lay is deterministic and known. Transportation time of fabric lays between spreading table and cutting machine is negligible. Fabric lays are known in advance. One machine is continuously available and is never kept idle while work is waiting. No fabric lay pre-empt is permitted.
Hybrid flowshop scheduling model 127
Figure 7. Performance with 40 populations
Figure 8. Performance with 80 populations
Table III shows the spreading sequence of the spreading machine m1, m2, m3, m4, m5 and m6 and the cutting sequence of fabric lays of the two computerized cutting machines m7 and m8 generated on the 2nd tier of the scheduling system. The details of each fabric lay are described in Table IV. After 250 generations with 80 populations, convergence occurred and the completion time of the operations in the cutting department was 703 minutes, while the production quantities required by the sewing department at a predetermined time could be reached.
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Table III. Spreading and cutting sequence of cutting department
m1
m2
m3
m4
m5
m6
15 25 43 56 7 22 27 4 14 6 13 21 33 19 2 11 35 46
42 31 26 8 55 30 34 17 38 54 16 51 44 12 49 3 39 23 52 40
9 37 45 47 20 50 32 5 24 18 1 10 29 41 28 36 48 57 53
80 96 70 101 75 82 87 78 90 85 79 66 93 100 73
84 92 86 74 81 62 68 59 83 102 88 91 64 95 97 77 89
61 58 98 60 99 63 67 94 71 72 76 65 69
m7 with idle time
m8 with idle time
15(0) 9(0) 42(0) 37(0) 45(0) 47(0) 31(5) 26(2) 25(0) 8(0) 43(0) 56(0) 20(0) 55(0) 7(0) 30(0) 34(0) 50(0) 17(0) 22(0) 32(0) 5(0) 24(0) 38(0) 18(0) 27(0) 4(0) 14(0) 54(0) 6(0) 1(0) 10(0) 16(0) 29(0) 51(0) 13(0) 44(0) 12(0) 49(0) 41(0) 21(0) 28(0) 3(0) 39(0) 36(0) 48(0) 33(0) 23(0) 57(0) 19(0) 52(0) 53(0) 2(0) 11(0) 35(0) 46(0) 45(0)
80(0) 61(0) 84(0) 96(0) 70(0) 92(0) 58(0) 86(0) 101(0) 74(0) 75(0) 98(0) 60(11) 81(0) 82(0) 62(0) 99(0) 63(0) 87(0) 68(0) 59(0) 67(0) 78(0) 83(0) 90(0) 94(0) 85(0) 71(0) 102(0) 88(0) 79(0) 91(0) 72(0) 66(0) 64(0) 76(0) 65(0) 95(0) 97(0) 93(0) 100(0) 69(0) 73(0) 77(0) 89(0)
X
SS
X
P
X
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51
1 1 1 2 1 3 2 2 2 2 2 2 2 2 2 2 4 4 4 4 4 4 4 2 4 2 2 2 4 1 4 3 2 3 2 2 2 3 2 4 2 1 2 2 3 3 2 2 3 2 2
21 18 18 11 6 96 36 36 62 23 25 21 110 128 92 56 140 156 157 157 155 139 156 56 156 45 24 70 139 5 140 53 2 8 1 44 26 86 70 125 22 5 21 10 61 62 22 26 99 19 28
G
X S
X C
X 21 18 18 22 6 288 72 72 124 46 50 42 220 256 184 112 560 624 628 628 620 556 624 112 624 90 48 140 556 5 560 159 4 24 2 88 52 258 140 500 44 5 42 20 183 186 44 52 297 38 56
9 8 8 7 5 53 14 14 25 10 11 10 47 52 38 24 82 91 92 92 91 81 91 25 104 21 11 33 81 5 82 30 4 6 4 20 11 49 33 73 11 5 11 7 38 38 11 12 57 9 12
6 6 6 9 6 15 10 10 10 10 10 10 10 10 10 10 19 19 19 19 19 19 19 9 18 9 9 9 19 6 19 15 9 15 9 10 10 15 9 19 9 6 9 9 15 15 9 10 15 10 10
X 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102
SS
X P
X G
X S
X C
X 2 2 4 2 2 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 2 2 4 4 4 4 4 2 2 2 4 4 4 3 3 2 1 2 2 1 1 2 3 2 2 2 3
128 131 88 38 50 149 199 112 196 103 102 147 130 129 170 170 119 118 99 183 186 172 146 163 64 142 151 182 151 174 145 151 150 151 158 196 196 9 7 9 5 10 41 20 12 106 60 46 86 74 21
256 262 352 76 100 596 796 448 784 412 408 588 520 516 680 680 476 472 396 732 744 688 584 652 128 284 604 728 604 696 580 302 300 302 632 784 784 27 21 18 5 20 82 20 12 212 180 92 172 148 63
54 55 54 19 23 92 80 47 79 42 42 59 54 52 70 70 49 49 41 73 76 70 59 65 18 39 62 73 62 71 58 43 43 43 64 79 79 5 4 4 3 5 19 8 6 42 33 21 36 32 11
Notes: X = job; SS
X = number of garments being drawn on the marker; P
X = number of fabric plies; S
X = total spreading time of fabric lay; C
X = cutting time of fabric lay
10 10 19 10 10 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 19 10 10 19 19 19 19 19 10 10 10 19 19 19 15 15 9 6 9 10 7 7 10 15 10 10 10 15
Hybrid flowshop scheduling model 129
Table IV. Characteristics of fabric lays
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The total operation time of cutting machine m7 was 688 minutes in which five and two minute idle times occured on job 31 and 26 respectively. The total operation time of cutting machine m8 was 703 minutes with 11 minutes idle time occurring on job 60. Thus the completion time of operations of the cutting department was 703 minutes since the longer operation time of the cutting machine, i.e. cutting machine m8, was counted as the two computerized cutting machines were operated simultaneously. Table V shows the planned quantities of garments required by the sewing department at four predetermined times: (1) 175 minutes; (2) 350 minutes; (3) 525 minutes; and (4) 700 minutes. Table V also shows the quantities of garments generated by the SCS scheduling system in which the quantities of garments required by the sewing department could be fulfilled by the cutting department. 6. Conclusion This paper has addressed the integration of a real hybrid flowshop and earliness and tardiness scheduling problem in the apparel industry. In this paper, a new model of two-tier hierarchy of garment manufacturing scheduling system has been designed. This new theoretical framework solves the master production schedule and spreading and cutting schedule. The traditional production planning and scheduling method has been changed significantly. We have considered the constraint of required numbers of garments, spreading capacity and cutting sequence within the hybrid flowshop setup of the cutting department. By using the proposed heuristics, the experimental results indicate that the MPS with minimized earliness and tardiness penalties can be prepared and completion time of operations in the cutting department and lateness of garments delivered to the sewing department can be minimized in the apparel industry. The research here can be extended to the scheduling of the operations in fusing, pressing and other departments of apparel manufacture.
Table V. Comparison between quantities of garment required by the sewing department and quantities of garment generated by GA-based SCS scheduler
Time (start at 0 min) 175 350 525 700
mins mins mins mins
Number of Total number of Number of Number of garments required garments provided garments provided garments provided by the cutting by the cutting by the sewing by the cutting machine m8 department department machine m7 7,500 8,000 7,000 6,500
2,861 3,015 2,708 2,861
4,721 5,536 4,380 3,739
7,582 8,551 7,088 6,600
References Chung, Y.L., Surya, L.D. and Chen, S.L. (1991), ``Minimizing weighted number of tardy jobs and weighted earliness-tardiness penalties about a common due date'', Computers & Operations Research, Vol. 18 No. 4, pp. 379-89. Cleveland, G.A. and Smith, S.F. (1989), ``Using genetic algorithms to schedule flow shop release'', Proceedings of the 3rd International Conference on Genetic Algorithms, pp. 160-9. Fouad, R., Abdelhaki, A. and Salah, E.E. (1998), ``A hybrid three-stage flowshop problem: efficient heuristics to minimize makespan'', European Journal of Operational Research, Vol. 109, pp. 321-9 Goldberg, D.E. (1989), Genetic Algorithms in Search, Optimization and Machine Learning, Addison-Wesley, Reading, MA. Gupta, J.N.D., Hariri, A.M.A. and Potts, C.N. (1997), ``Scheduling a two-stage hybrid flow shop with parallel machines at the first stage'', Journal of Ann. Oper. Res., Vol. 69, pp. 171-91. Hoogeveen, J.A., Lenstra, J.K. and Veltman, B.(1996), ``Preemptive scheduling in a two-stage multiprocessor flow shop is NP-hard'', European Journal of Operation Research, Vol. 89, pp. 172-5. Lee, C. and Kim, S. (1995), ``Parallel genetic algorithms for the tardiness job scheduling problem with general penalty weights'', International Journal of Computers and Industrial Engineering, Vol. 28, pp. 231-43. Lee, C.Y. and Choi, J.Y. (1995), ``A genetic algorithm for job sequencing problems with distinct due dates and general early-tardy penalty weights'', Computers & Operations Research, Vol. 22 No. 8, pp. 57-69. Linn, R. and Zhang, W. (1999), ``Hybrid flow shop scheduling: a survey'', Computers and Industrial Engineering, Vol. 37, pp. 57-61. Li, Y., Ip, W.H. and Wang, D.W. (1998), ``Genetic algorithm approach to earliness and tardiness production scheduling and planning problem'', International Journal of Production Economics, Vol. 54, pp. 65-76. Lo, K.N. (1997), ``Computer aided system for optimal capacity planning in garments manufacture'', MPhil thesis, The Hong Kong Polytechnic University. Man, Tang, K.S. and Kwong, S. (1996), ``Genetic algorithms: concepts and applications'', to appear in IEEE Transactions on Industrial Electronics. Shintaro, M., Teruo, M. and Hiroaki, I. (1999), ``Bi-criteria scheduling problem on three identical parallel machines'', International Journal of Production Economics, Vol. 60-61, pp. 529-36. Vignier, A. (1996), ``Resolution of some two-stage hybrid flowshop scheduling problems'', IEEE International Conference on Systems, Man and Cybemetics, Information Intelligence and Systems, Vol. 4, pp. 2934-41. Wong, W.K., Chan, C.K. and Ip, W.H. (2000a), ``Optimization of spreading and cutting sequencing model in garment manufacturing'', Computers in Industry, Vol. 43, pp. 1-10. Wong, W.K., Chan, C.K. and Ip, W.H. (2000b), ``Effects of spreading-table quantities on the spreading-table planning of computerized fabric-cutting system'', Research Journal of Textile and Apparel, Vol. 4 No. 1, pp. 25-36.
Hybrid flowshop scheduling model 131
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IJCST 13,2
132 Received October 2000 Revised December 2000 Accepted December 2000
The effect of a durable flame-retardant finishing on the mechanical properties of cotton knitted fabrics P. Mamalis
CLOTEFI S.A., Athens, Greece, and
A. Andreopoulos and N. Spyrellis
Department of Chemical Engineering, National Technical University of Athens, Greece Keywords Flame resistant, Mechanical properties, Cotton Abstract Some of the basic mechanical characteristics such as tensile, bending, shear, compression, and surface properties of cotton knitted fabrics after a durable flame-retardant finishing, were studied by the objective-evaluation method developed by Kawabata and Niva using the KES-F system. In addition, properties such as bursting strength, drape and sewability were studied in order to further explore the influence of this treatment on the fabrics. All treated fabrics were flame-retardant but their mechanical properties showed changes as a result of the above finishing. More specifically, a significant reduction in the bending and shear properties was recorded, which suggests that the flame-retardant finishing primarily affects the above characteristics.
1. Introduction Many studies on the objective assessment of mechanical properties have been made using woven fabrics (Matsudaira and Matsui, 1992a; 1992b; Matsudaira, 1994). On the other hand, there are very few data on the knitted fabrics as well as on the effect of a finishing procedure on the quality of knits (Matsudaira and Matsui, 1992b; Matsudaira, 1994; Finnimore, 1985). This lack may partly be explained by the fact that the possibilities for altering the handle of knitted fabrics are limited compared with those of woven (Okamoto, 1985; Almeida and Cavaco-Pavlo, 1991). In the case of single jersey cotton knitted fabrics, the effect of the flame-retardant finishing on the mechanical properties is significant. We selected two different types of single jersey knitted fabrics and have treated them with a flame-retardant finish and a softener. In the work presented in this paper, changes in the mechanical properties such as tensile, bending, shear, compression, surface, bursting, drape and sewability properties of cotton knitted fabrics after a durable flame-retardant finishing are investigated at each stage by the objective-evaluation method developed by Kawabata and Niva in which the KES-F system and bursting, drape and sewability testers are used. International Journal of Clothing Science and Technology, Vol. 13 No. 2, 2001, pp. 132-144. # MCB University Press, 0955-6222
The authors would like to express their gratitude to Professor G. Stylios for his invaluable advice in writing this paper and CLOTEFI S.A. for the experimental part carried out in its textile laboratory.
2. Experimental 2.1 Samples A number of samples from two different types of single jersey cotton knitted fabrics, i.e. Fabric A and Fabric B, which are typical representatives of this category of textiles, were finished and tested, in a four-stage procedure. These products are used mainly for outerwear garments such as T-shirts, women's dress and children's wear. Their technical data are shown in Table I. The finishing stages (Matsudaira and Matsui, 1992b) followed in this study are listed in Table II.
Durable flame-retardant finishing 133
2.2 Finishing procedures Five samples from each type of fabrics were treated. A typical procedure for application of a flame-retardant finishing consists of the stages below: (1) Impregnation in the finishing solution (pick up: 80 per cent). (2) Drying (up to 1308C, 30 min). (3) Curing (1608C, 90 sec). (4) Washing off (aqueous soda 10g/l with pH = 10.5, 808C, 15 min ± rinse 458C for 10 min ± rinse cold for 10 min, pH = 8.5). Similarly, the softening procedure (Almeida and Cavaco-Pavlo, 1991) can be described by the following parameters: . Liquor ratio: 1:15. . Softening agent: 3-4 per cent w/w. . Temperature: 408C. . Time: 20 min. . pH = 5-5.5.
Fabric A Fabric B
Composition
Gauge/inch
Density (loops/cm)
Linear density (Ne)
Weight (g/m2)
100% Cotton 100% Cotton
28/30 20/30
21 19
30/1 20/1
124 155
Number
Finishing stages
1 2 3 4 5
Knitting mill Finishing with Post treatment Finishing with Post treatment
flame-retardant with softening agent flame-retardant/softening agent with softening agent
Table I. Outline of samples
Table II. Finishing stages of cotton knitted fabrics examined
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From Table II it is shown that each sample used in this work was finished according to the following schedule: (1) without softening agent; (2) the finished samples are treated with a softening agent;
134
(3) five new samples of the raw material were finished with a soften agent in the flame-retardant finishing solution (a total of ten samples from each type of fabrics were tested and the results are the mean value of these measurements); and (4) the finished samples are treated with a soften agent again. After finishing all samples were tested in a flammability tester and were found to be flame-retardant. 2.3 Method of measurement All measurements were carried out at 20 28C and 65 2 per cent r.h. Before the flame-retardant finishing (original specimen) and after each stage of treatment the basic tensile, bending, shear, compression, and surface properties of single jersey cotton fabrics were measured by the KES-F system using the set-up of knits standard sensitivity (Matsudaira and Matsui, 1992b). The bursting strength, drape and sewability were measured according to the methods indicated in Table III. 3. Results 3.1 Tensile properties The changes of tensile characteristics, introduced by the finishing stages, to the two different cotton knitted fabrics, are shown in Figures 1-3. From these figures it is clear that the linearity of the load/extension curve, LT, of the two fabrics increased approximately 10 per cent. Also, the tensile energy, WT, increased for Fabric A about 20 per cent and decreased for Fabric B about 5 per cent except for stage 5 where an increase of 12 per cent was recorded. With respect to the tensile resilience, RT, a decrease of 20 per cent for Fabric A and 10 per cent for Fabric B can be observed. The changes in tensile characteristics were small, which suggests a negligible effect of the flame-retardant finishing and softening on this property.
Property Bursting strength Table III. Drape Properties and methods Sewability
Method
Instrument
BS 4768 Manufacturer instructions Manufacturer instructions
Bursting tester Drape tester Sewability tester
Durable flame-retardant finishing 135
Figure 1. Changes of tensile characteristics (LT) of different cotton knitted fabrics after finishing
Figure 2. Changes of tensile characteristics (WT) of different cotton knitted fabrics after finishing
3.2 Bending properties The results obtained from bending measurements of the finished fabrics are shown in Figure 4. Regarding Fabric A, it can be seen that bending rigidity (B) and hysteresis of the bending moment (2HB) show an increase of 70 per cent after treatment with the flame-retardant, compared with the values corresponding to the knitting mill fabric. The bending properties increased 60 per cent after stage 5. This shows that the fabric remains stiff, despite the fact that it was treated twice with the softening agent.
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Figure 3. Changes of tensile characteristics (RT) of different cotton knitted fabrics after finishing
Figure 4. Changes of bending characteristics (B and 2HB) of different cotton knitted fabrics after finishing
As far as Fabric B is concerned, bending rigidity (B) increased 90 per cent and hysteresis of the bending moment (2HB) increased 95 per cent after the flameretardant finishing stage, with reference to the knitting mill fabric. On the other hand, bending rigidity B increased 95 per cent and hysteresis of the bending moment 2HB increased 137 per cent after stage 5. Therefore, the effect of the flame-retardant finishing on bending characteristics seems to be stronger in the case of Fabric B. 3.3 Shear properties As to the shear characteristics of the samples tested after the finishing stages, the results obtained are shown in Figures 5-7.
Durable flame-retardant finishing 137
Figure 5. Changes of shear characteristics (G) of the two fabric samples after the finishing stages
Figure 6. Changes of shear characteristics (2HG) of the two fabric samples after the finishing stages
The shear stiffness (G) of Fabric A increased to 77 per cent, whereas the hysteresis of the shear force ( 2HG and 2HG3) showed a much higher increase of 145 per cent and 149 per cent respectively, after treatment with the flameretardant. Furthermore, the shear stiffness increased 53 per cent and hysteresis of the of shear force (2HG and 2HG3) increased 91 per cent and 98 per cent respectively after stage 5. The shear characteristics display a similar response with those of bending during various treatments. This is additional evidence
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Figure 7. Changes of shear characteristics (2HG3) of the two fabric samples after the finishing stages
that the fabric remains stiff, regardless of the two subsequent treatments with softening agents. As far as Fabric B is concerned shear stiffness (G), increased 82 per cent and hysterisis of the shear force (2HG and 2HG3), considerably increased 115 per cent and 122 per cent respectively, at the flame-retardant finishing stage of the values for the knitting mill fabric. The shear stiffness increased 80 per cent and hysterisis of the shear force (2HG and 2HG3), increased 114 per cent and 121 per cent respectively, with treatment of the stage 5. The shear characteristics are affected in a similar mode to that observed with the bending properties. The effect of the flame-retardant finishing on shear characteristics is stronger in the case of Fabric B. 3.4 Compression properties The effect of finishing with a flame-retardant as well as of the subsequent treatments on the compression properties of the two different cotton knitted fabrics is shown in Figures 8-10. It can be seen that for Fabric A the linearity of the compression/thickness curve LC increases 23 per cent, the compression energy WC increased 17 per cent, whereas the compression resilience RC decreased 30 per cent due to the treatment with the flame-retardant at the finishing stage of the values for the knitting mill fabric. On the other hand, the linearity of the compression/ thickness curve LC decreased slightly by 5 per cent, the compression energy WC increased 42 per cent and the compression resilience RC decreased 34 per cent after the post treatment with softening agent, which was performed in stage 5. As far as Fabric B is concerned the linearity of the compression/thickness curve LC increased 37 per cent, the compression energy WC increased 44 per
Durable flame-retardant finishing 139 Figure 8. Changes of compression characteristics (LC) of two different cotton knitted fabrics introduced by finishing stages
Figure 9. Changes in the compression characteristics (WC) of two different cotton knitted fabrics introduced after the finishing stages
cent and the compression resilience RC decreased 29 per cent as a result the flame-retardant finishing stage. Similarly, the linearity of the compression/ thickness curve LC increased 15 per cent, the compression energy WC increased 55 per cent and the compression resilience RC decreased 26 per cent after the post treatment in stage 5. The above results suggest that fabrics became rather stiff, taking their deformability in compression as a criterion. 3.5 Surface properties The changes of surface properties of the two different cotton knitted fabrics introduced by the finishing stages are shown in Figures 11-13.
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140 Figure 10. Changes in the compression characteristics (RC) of two different cotton knitted fabrics introduced after the finishing stages
Figure 11. Changes in the surface characteristics (MIU) of two different cotton knitted fabrics after treatment in the various finishing stages
It is evident that the friction coefficient MIU, displays a slight increase of 4.7 per cent, for Fabric A with its mean deviation MMD, increasing to a 4.9 per cent, whereas the geometrical roughness SMD shows a decrease of 37.6 per cent compared to the values for the knitting mill fabric. The friction coefficient MIU decreased 9.9 per cent, its mean deviation MMD decreased to 6.2 per cent and the geometrical roughness SMD decreased 10.1 per cent after stage 5. On the other hand, in the case of Fabric B the frictional coefficient MIU decreased 7.6 per cent, its mean deviation MMD decreased 19.4 per cent, whereas the geometrical roughness SMD increased slightly by 0.3 per cent at the flame-retardant finishing stage. The frictional coefficient MIU decreased
Durable flame-retardant finishing 141 Figure 12. Changes in the surface characteristics (MMD) of two different cotton knitted fabrics after treatment in the various finishing stages
Figure 13. Changes in the surface characteristics (SMD) of two different cotton knitted fabrics after treatment in the various finishing stages
13.2 per cent, its mean deviation MMD decreased remarkably 24.2 per cent and the geometrical roughness SMD decreased 3.31 per cent by the stage 5. Since the changes in the surface properties of the fabrics are small, the effect of the finishing stages could be characterized as weak. 3.6 Bursting strength, drape and sewability The changes in bursting strength, drape and sewability of the cotton knitted fabrics introduced by the treatment performed during the various finishing stages are presented in Table IV.
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Table IV. Changes in the bursting strength, drape and sewability
Finishing stages Fabric A No. 1 Knitting mill No. 2 Flame-retardant finishing without softening agent Change (%) No. 5 Post treatment with softening agent Change (%) Fabric B No. 1 Knitting mill No. 2 Flame-retardant finishing without softening agent Change (%) No. 5 Post treatment with softening agent Change (%)
Bursting strength) (kg/cm2) 7.65
Drape (%) 42.24
5.52 ±27.8
76.7 +81.6
5.6 ±26.8
69.7 +65
7.8
40.7
Sewability 14.4 35.5 +146.5 6.75 ±53.1 8
6.33 ±18.8
69.6 +71
11 +37.5
5.1 ±34.6
78.8 +93.6
13 +62.5
Regarding Fabric A, bursting strength decreased 27.8 per cent, the drape increased to 81.6 per cent, whereas its sewability increased to 146.5 per cent after the flame-retardant finishing stage. The above changes were: ±26.8 per cent, +65 per cent and ±53.1 per cent respectively, after stage 5. These results clearly show that the fabrics became weak, rough and stiff. As far as Fabric B is concerned the bursting strength, decreased 18.8 per cent, its drape increased 71 per cent, whereas the sewability increased 37.5 per cent compared with the values for the knitting mill fabric after the finishing stage. The bursting strength decreased 34.6 per cent, its drape increased 93.6 per cent, whereas the sewability increased 62.5 per cent after stage 5. The above results mean that the fabrics became weak and they lost their softness and displayed a worse drape. 4. Discussion The above experimental work allows us to assess the changes in mechanical properties of cotton knitted fabrics after application of a durable flameretardant finishing. The KES-F system seemed to provide a means of identifying and quantifying mechanical properties such as tensile, bending, shear, compression and surface characteristics, which are expected to be influenced by this finishing. However, some problems and limitations were encountered and are presented below: (1) During the finishing process it was observed that high pressure on the padder, had a negative effect on the flame-retardance of the fabric. (2) When measuring the knitted fabrics on the KES-F instruments (Finnimore, 1985):
.
.
Knit fabrics tend to roll at the edge after cutting, which can give problems especially on the bending tester. Therefore, the testing procedure was modified using two plastic templates in order to insert the samples into the chucks. When measuring tensile properties the fabrics were extensible especially in the course direction. In order to overcome this problem the following adjustments were performed, based on instructions of the manual of tensile tester: the maximum tensile force was reduced from 500cN/cm to 250cN/cm and the sample length was reduced from 5cm to 2.5cm.
After the process of flame-retardant finishing the stiffness parameters, especially bending and shear properties, show significant increase. The curves of Figure 4 as well as Figures 5-7 clearly show that the remarkable effect of the flame retardant finishing on fabric mechanical properties can be expressed quantitavely by carrying out, for example, a bending or shear deformationrecovery cycle. The fabric bending and shear rigidity and more interestingly, the bending and shear hysteresis can be calculated from the bending and shear curves. These parameters are greatly influenced by the flame-retardant finishing and therefore, they can become a reference for quality control during production cycles. This has also been reported by other authors (Finnimore, 1985; Hamilton and Postle, 1997; Scardino, 1985) who already stated the great importance of bending and shear properties of knitted fabrics. Although, treatment with a softening agent caused some reduction to these properties, the initial effect still remains clear. In addition, properties such as strength, drape and sewability deteriorated. Comparing Fabric A and Fabric B, we can conclude that the effect of finishing procedure was slightly stronger in Fabric B. It is obvious that the flame-retardant procedure leads to a reduction in the bending and shear properties of knitted fabrics and treatments such as softening has only a small corrective effect on the softness of the fabrics. Owing to the stiffness of the treated fabrics problems will be encountered during processing in the cutting and sewing rooms. Therefore, alternative after finishing treatments should be established, aiming at the elimination of the above-mentioned negative effects of this finishing procedure. 5. Conclusions From the results obtained in the above study the following conclusions can be drawn: . Small changes in the tensile characteristics of the fabrics and a weak effect of the flame-ratardant finishing and softening were recorded. . The bending characteristics of the fabrics increased. This means that the fabrics became stiff, despite the fact that they were treated twice with a softening agent.
Durable flame-retardant finishing 143
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144
.
.
.
.
The most significant effect of the durable flame-retardant finishing on knitted fabrics is a reduction of the shear properties. The shear characteristics of the fabrics increased in the same manner as the bending characteristics. This means that the fabrics became stiff, although treated twice with a softening agent. The compression characteristics of the fabrics increased and the fabrics became rather hard in compressional deformation. As the changes in the surface properties of the fabrics are small, the effect of the finishing stages seems to be weak. A great reduction in the bursting strength, drape and sewability of the fabrics was recorded after the flame-retardant finishing stage and the fabrics became weak and stiff. They lost their softness and showed worse drape.
References Almeida, L. and Cavaco-Paulo, A. (1991), Proceedings of a Seminar, British Textile Technology Group, Lecture 10. Finnimore, E. (1985), ``Objective handle parameters of knitted outerwear fabrics'', Proceedings of 3rd Japan-Australia Symposium, Textile Machinery Society of Japan, p. 45. Hamilton, R.J. and Postle, R. (1997), J. Text., Vol. 44, p. 336. Matsudaira, M. (1994), ``The mechanical properties and fabric handle of polyester-fibre shingosen fabrics'', J. Text., Vol. 85, p. 158. Matsudaira, M. and Matsui, M. (1992a), ``Features of mechanical properties and fabric handle of silk weaves'', J. Text., Vol. 83, p. 133. Matsudaira, M. and Matsui, M. (1992b), ``Changes in the mechanical properties and fabric handle of polyester-fibre fabrics through the finishing stages'', J. Text., Vol. 83, p. 144. Okamoto, Y. (1985), ``Influence of repeated dry-cleaning on the handle of men's suitings'', Proceedings of 3rd Japan-Australia Symposium, Textile Machinery Society of Japan, p. 743. Scardino, F. (1985), ``Evaluation of industrial fabrics with the KES-F'', Proceedings of 3rd JapanAustralia Symposium, Textile Machinery Society of Japan, p. 633.
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Numerical study of the mechanical behaviour of textile structures Mostapha Tarfaoui ENSITM, France and
Samir Akesbi
Laboratoire de MatheÂmatiques, Faculte de Sciences et Techniques, Universite de Haute Alsace, France Keywords Finite element, Numerical methods, Textiles, Stress analysis Abstract The arrangement as well as the properties and the structure of the fibres within the yarn and the yarns within the fabric generate a complex mechanism of deformation in such material. Therefore, intends to develop a theoretical model of the mechanical behaviour of the twill weave based on previous researches concerning the simplest plain weave. However, scaling up from the plain to the twill weave is not a direct transformation due to the non-symmetry of the latter. The finite element method does not require simplifying hypotheses. Thus, it is possible to simulate different stresses, to determine the fabric response and to compare the behaviour of the various structures. This simulation requires the use of a realistic meshing of the basic cell and an accurate characterisation of the physical parameters of the material that composes the basic cell. Assuming the material to be elastic, the derived and, consequently, the discreet mathematical formulations of the problem have both been solved. The coefficients from those formulas are then used in the Modulef software. For each stage of the development, uniaxial, biaxial and perpendicular to the fabric plan, tensile tests have been simulated, as well as pure shear testing. The next step consisted of computing the Tresca and Von Mises stresses within the basic cell and the micro-stress field within the basic cell components.
1. Introduction To implement the technique of the finite elements, it has been supposed that the element is periodic, i.e. that it admits a geometrical and mechanical periodicity to enable it to be defined on the basis of one period acknowledged, recognised as the basic cell T (Figure 1). In every model defined by its partial derivative equation of the fabric mechanical behaviour and whatever the method of homogenisation employed to obtain a homogeneous model, we will be reduced to solving a cellular problem. The three-dimensional structure of the basic cell of the various fabrics is very complex. This study starts by meshing the different fabrics, which will enable us to take into account the geometry as well as the characteristic mechanics of the yarn and the applied stresses. Then some models, neglecting one or another of both components, will be presented. International Journal of Clothing Science and Technology, Vol. 13 No. 3/4, 2001, pp. 166-175. # MCB University Press, 0955-6222
2. Pierce's geometrical model This model, which was developed by Pierce (1937), is the most conventional and the oldest. In this model, the warp and weft yarns show two-dimensional
Mechanical behaviour of structures 167
Figure 1. Concept of basic cell
trajectories. Circular and compressible sections ideally represent these yarns, and segments and circles (Figure 2) represent their trajectories. Owing to this specific geometry, it is only possible to carry out calculations on the plain weave (structure presenting the smallest weave ratio that can be woven), because this model permits only treatment of simple fabrics. Once the yarns are incompressible and perfectly flexible, the yarn curvature is uniform and imposed by the cross-section of the intersected yarns. The geometrical parameters are defined by the following equations: D d1 d2 l1 c1 1 p2 l2 1 c2 p1 p1
l2 D2 cos 2 D sin 2 p2
l1
D1 cos 1 D sin 1
h1
l1
D1 sin 1 D
1
cos 1
h2
l2
D2 sin 2 D
1
cos 2
1
where: d1, d2: diameters of the warp and weft yarns, l1, l2: lengths of the warp and weft yarns between two planes including two consecutive yarns of the perpendicular system, p1, p2: distances between the warp and weft yarns,
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y1, y2: inclination angles of warp and weft yarn in relation to the plane of the fabric for the two warp and weft systems, h1, h2: maximum displacements of the warp and weft yarn axes, normal to the plan of the fabric, c1, c2: warp and weft shrinkages. The difficulty of this model is related to the flatness of yarns on the contact points. To reduce the errors originated by yarn flatness, Pierce had used the equations derived from the geometry of circular cross-sections obtained by replacing the diameter of yarns by the small axis of an elliptic section (Figure 3). This assumption is valid only for not very tight structures. 3. Kawabata's mechanical models First, Kawabata et al. had developed a model based on biaxial traction and proposed a fabric structure similar to that of Pierce, but represented in a different way. In Kawabata et al.'s model, the warp and weft yarns are represented by straight lines that bend in two points P1 and P2 on the perpendicular axis to the fabric plane (axis Z). This model is illustrated in Figure 4: yic, yit: distances between two warp yarns and two weft yarns, hic, hit: distances from the points P1 and P2 to the origin (Q,X,Y,Z), lic, lit: lengths of warp and weft yarns, yic, yit: inclination angles of warp and weft yarns, Nic, Nit: accounts in warp and weft.
Figure 2. Geometrical model of Pierce
Figure 3. Intersection with elliptic sections
Mechanical behaviour of structures 169 Figure 4. Structure of fabric proposed by Kawabata et al.
Under the tensile load in X and Y directions and supposing perfectly flexible warp and weft yarns, the deformation can be schematised as shown in Figure 5. In this Figure the symbols are defined as follows: A1, A2: tensile properties of warp and weft yarns, B1, B2: compression properties of warp and weft yarns, lc, lt: elongation rate of the fabric along axes X and Y, Fx, Fy: forces along axes X and Y, Tc, Tt: tensile loads of warp and weft yarns, Fco: compressive lateral force acting along axis Z at the point of contact between warp and weft yarns:
length after deformation : initial length
When the fabric is subject to an elongation along the axes X and Y with lx and ly, lc and lt can be deduced by a simple geometrical estimation as follows:
Figure 5. Structure unit deformed of Kawabata et al.
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s 4h22t
y y1t 2 t 4h21t y21t s 4h22c
x y1c 2 c 4h21c y21c
170
2
3
The static equilibrium equations of the structure at the deformed state can be represented by the tensile properties of warp and weft yarns: Tc gc
c
Tt gt
t
Consequently, the following relations can be obtained: gc
c x y1c Fx r 2 2 4h2c y1cx
4
gt
tc y y1t Fy q 4h22t
y y1t 2
5
2h2c 2h2t Fco 2gc
c q 2gt
t q 4h22c
x y1c 2 4h22t
y y1t 2
6
Thus, there appears to be a need to know the properties of yarn extension represented by the functions gc(lc) and gt(lt), as well as the yarn behaviour in compression. 4. Energy methods In a relaxed fabric, the yarns inside the fabric are arranged so that the energy of the system is minimal. The energy method consists, therefore, of the identification and the formulation of all individual contributions to the system energy. The study of the textile structural deformations reveals four terms of deformation energy (De Jong and Postle, 1977a,b,c, 1978; Postle and De Jong, 1981): Et: energy of yarn longitudinal extension, Ec: energy of yarn lateral compression, Er: energy of yarn twist, Eb: energy of yarn bending. The energy stored in a textile structure is the sum of those four energies and is given by: E
n Z X i1
0
li
Et Ec Er Eb i ds
7
5. Mesh of the basic cell of plain and twill weaves 5.1 Notion of basic cell To implement the technique of finite element, the element has to be periodic, i.e. it possesses a geometrical and mechanical periodicity which permits definition from the knowledge of one period, known as basic cell T (Figure 6). This period is small in size compared with that of the fabric structure. The range defined by T is located by the Cartesian co-ordinates (x, y, z) in an orthonorm reference mark ~ k
o; k1 ; k2 ; k3 .
Mechanical behaviour of structures 171
5.2 Mesh of the basic cell 5.2.1 Mesh of the plain weave. The three-dimensional mesh of the basic cell, a very significant stage in the use of the finite element method, consists of hexahedrons ± the selected LaGrange's interpolation of the first degree. This mesh (Figure 7) is obtained by following the subsequent steps: A. Mesh of the cross-section The cross-section of the yarns is meshing by quadrangles with four nodes that also represent the vertices. B. Mesh of the yarn This mesh is obtained from the basic section, to which are applied adequate translations of well-defined vectors. The parameter that will influence the final mesh of the basic cell and must therefore be taken into account is the curvature of the yarn. Then, the three other yarns that compose the basic cell should be meshed. These yarns are obtained from F1 by using geometrical transformations of rotation, translation and symmetry types. During this stage the notions of subfields and references faces start to appear. The sub-fields allow one to characterise a fabric by the voluminal efforts f
that are applied to them and by the characterisation of the mechanical properties of the materials that constitute the warp and weft yarns. The reference faces are the sites of surface effort f of the type tensile, shearing.
Figure 6. Sight under the electron microscope of the plain fabric
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Figure 7. The different stages of the mesh of the basic cell of plain weave
C. Sticking the different components The sticking of the four yarns must take into account the type of contact between warp and weft yarns that compose the basic cell. In fact, the number of common points and common surfaces inform us which type of contact occurs on yarn crossing. If the parameter that characterises the yarn curvature is not taken into account, holes will appear in the final mesh. 5.2.2 Meshes of the twill weave. The basic cell of twill weave is composed of three warp yarns that intersect three weft yarns (Figure 8). These yarns present a different type of undulations among them, that imply a complex calculation for the mesh of yarns and, consequently, of the cell itself, that takes into account the type of contact between warp and weft yarns. The mesh of the basic cell of twill weave is identical to the plain weave (Figure 9). In fact, this mesh starts with the circumscription of the geometrical profile of the cross-section of the different yarns that compose the basic cell. 6. Localization of the stresses in plain and twill fabrics A series of numerical calculations has been carried out in the plain and twill fabrics using the code Modulef computer and specific programs that have been developed to compute the different stresses.
Mechanical behaviour of structures 173 Figure 8. Sight under the electron microscope of the structure of twill
Figure 9. Various stages of the mesh of the basic cell of twill fabric
We were thus interested in the localization of the micro-stresses induced in the woven structure by various loads corresponding to states of given macrostresses: P P (1) Uniaxial tensile in the direction of warp yarn: 11 100MPa, ij 0 for
i; j 6
1; 1, with boundary conditions of the blocking type on sides 3 and 4; P P (2) Biaxial tensile: 11 100MPa; 22 100MPa; P (3) Pure shear in the plan of the fabric: 12 100MPa, for
i; j 6
1; 2;
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(4) Tensile-Z: tensile P in the direction perpendicular to the basic cell P 100MPa; 33 ij 0, for
i; j 6
3; 3, with boundary conditions of the blocking type on sides 3 and 4. For the three macroscopic loads presented above, the tables provide the following stresses: (1) the minimum and the maximum of the equivalent stress of Tresca in the basic cell, (2) the minimum and the maximum of the equivalent stress of Von Mises in the basic cell, (3) the minimum and the maximum of the stresses induced in each yarn. We obtain many results for different kind of macro-stresses. An example is presented to illustrate this work. A simulation of the mechanical behaviour of the basic cell under a biaxial tensile stress is presented in Figure 10 and Table I.
Figure 10. Modelling of the mechanical behaviour of the plain weave under the action of biaxial tensile
Biaxial tensile Tresca xx yy zz xy Table I. Stresses (MPa) in the basic cell under biaxial tensile strength
xz yz
Min Max Min Max Min Max Min Max Min Max Min Max Min Max
S1
S2
S3
S4
3 128 0 147 0 97 0 36 ± 41 41 ±9 10 ± 32 32
3 128 0 148 0 97 0 36 ± 41 41 ±10 9 -32 32
3 128 0 97 0 148 0 36 ± 41 41 ± 32 32 ± 10 9
3 128 0 97 0 148 0 36 ± 41 41 ± 32 32 ±9 10
7. Conclusion The modelling of textile structures by the finite element method is a new approach based on the combination of geometric and mechanical models. In fact, the characterisation of the mechanical behaviour implies first the definition of the geometry of fabric, then by the construction of the matrices of stiffness and the second member. The finite element method permits a construction and a representation of the fabrics by taking into account the yarn undulation, the existence or not of symmetries in the basic cell and the type of contact between warp and weft yarns. The different parameters permit one to obtain a mesh of weaves closest to the reality without any restriction and any simplifying assumption. In order to model the mechanical behaviour of plain and twill fabrics, we have subjected the fabrics to several types of stress (uniaxial tensile, biaxial tensile, tensile perpendicular to the plan of fabric and shear). Throughout the various simulations, the following conclusions can be highlighted: . The equivalent stress of Tresca T is higher than the applied macroP stress ( 100MPa) and is more significant for the blocked yarns (T 165MPa). . At the microscopic scale, the micro-strains induced in the yarn are significant in the direction of the solicitation. . In biaxial tensile, the Tresca stress is distributed in the same way on the four yarns that constitute the basic cell: T
S1 T
S2 T
S3 T
S4 128MPa. . A shear or a tensile along axis Z involves a very significant damage in the basic cell. Indeed, the Tresca stress can reach a value three to four times higher than the macroscopic stress. . The induced micro-stresses are more significant for the blocked yarns. References De Jong, S. and Postle, R. (1977a), ``An energy analysis of woven fabric mechanics by means of optimal-control theory. Part I: Tensile properties'', Journal of Textile Institute, Vol. 68, pp. 350-61. De Jong, S. and Postle, R. (1977b), ``An energy analysis of woven fabric mechanics by means of optimal-control theory. Part II: Pure-bending properties'', Journal of Textile Institute, Vol. 68, pp. 362-9. De Jong, S. and Postle, R. (1977c), ``An introduction to the study of fabric mechanics using energy methods'', Textile Institute and Industry, Vol. 15, pp. 376-9. De Jong, S. and Postle, R. (1978), ``A general energy analysis of fabric mechanics using optimalcontrol theory'', Textile Research Journal, Vol. 48, pp. 127-35. Kawabata, S., Niwa, M. and Kawai, H. (1973), ``The finite deformation theory of plain weaves fabric. Part I: The biaxial-deformation theory'', Journal of Textile Institute, Vol. 64, pp. 21-46. Pierce, F.T. (1937), ``The geometry of cloth structure'', Journal of Textile Institute, Vol. 28, pp. 45-96. Postle, R. and De Jong, S. (1981), ``The rheology of woven and knitted fabrics. Part I: Fabric geometry and force methods of analysis applied to fabric mechanics'', Journal of Textile Machinery of Japan, Vol. 34 No. 5, p. 264.
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The peculiarities of textile behaviour in biaxial punch deformation Eugenija Strazdiene and Matas Gutauskas
Kaunas University of Technology, Kaunas, Lithuania Keywords Textiles, Anisotropy, X-ray Abstract The goal of this research work was experimental investigation and evaluation of biaxial punch deformation processes of anisotropic textile materials. The investigation was aimed to solving the following problems: to find a new criterion for textile behaviour evaluation in punch loading; to evaluate the effect of material anisotropy for the geometry of formed shell; to determine the strain distribution in anisotropic shell. The experimental data of X-ray diffraction analysis showed that friction at specimen/punch contact, which earlier was ignored, has a significant effect upon the parameters of the punching process.
International Journal of Clothing Science and Technology, Vol. 13 No. 3/4, 2001, pp. 176-185. # MCB University Press, 0955-6222
1. Introduction The classical uniaxial tensile test that provides load-deformation dependency is an extensively used method for textile behaviour evaluation. Besides, there is a significant number of specific test methods based on the principle of biaxial (plain, membrane and punch) deformation (Kawabata, 1989; Kobliakov, 1973; Strazdiene et al., 1997). The advantage of the latter is better simulation of fabric behaviour in real service conditions (clothing, parachutes, sails, textile architecture, etc.). The majority of textile materials are highly anisotropic. Obviously their parameters must be determined in two or even more particular directions. Specimen preparation for the uniaxial tensile test is problematic, as cutting of precisely orientated samples with the exact width takes a long time. In addition, specimens often tear near clamps and such undesirable phenomena as thread falling or loop running are revealed, decreasing the reliability of experimental data. Specified problems do not occur in punch or membrane tests, because clamps (often circular or oval) hold the specimens round the closed contour and tearing zones appear in the centre part of the specimen (Daukantiene and Gutauskas, 1998). Besides, the same test can provide additional information concerning the anisotropy level of the materials. This article presents an investigation of textile behaviour in the punch deformation process. Although the punching test is well-known, the material behaviour in such specific deformation process has been insufficiently investigated. On the one hand, most standards give one concrete test method with strictly limited values of punch radii r and sample radii R (usually the ratio r/R takes value in the limits of 0.2 7 0.4). On the other hand, the material mechanical properties are determined only in response to maximum deflection height H and tearing force P. In the majority of earlier research works fabric properties in such biaxial deformation were determined by the increase of sample area DS (Kuprijanov,
1969; Flerova and Surikova, 1972; Kisilak, 1999), calculated as: DS = AH ± B, where A and B are concrete numerical coefficients: A = 13.7 and B = 87.5, respectively. The reliability of this expression is doubtful. First, coefficients A and B cannot be universal, i.e. common for all materials. Second, these coefficients were defined using a simplified model of specimen geometry modifying the flat textile sample into spatial shell. Our earlier investigations have shown that in the punch deformation of anisotropic textile material complicated shell is formed, the surface of which has areas of negative and positive curvature (Tijuneliene and Gutauskas, 1998). So, the surface cannot be simplified by the sum of sphere segment and cut cone. The object of this investigation was to extend the limits of r/R ratio and to find new criterion for anisotropic knitted fabric behaviour evaluation in punch deformation.
Textile behaviour in biaxial punch 177
2. Materials and methods Tests were carried out with tensile testing machine FP-10/1 equipped with the original test unit (Figure 1), having replaceable clamps for test specimen fixing and five punches of different sizes (Table I). The punch deformation unit was developed at Kaunas University of Technology (Lithuania).
Figure 1. Punch deformation unit
Symbols r1 r2 r3 r4 r5
Punches
radii r, mm
r/R
5.00 9.50 14.25 19.85 25.10
0.18 0.34 0.50 0.70 0.89
Table I. Punch characteristics
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The investigations were performed using disc shaped specimens (R = 28.2mm), cut from knitted materials with significantly different coefficients of anisotropy (Table II). The spatial geometry of formed shell was evaluated using AutoCAD 14 software on the basis of two perpendicular generating lines, the co-ordinates of which were determined by an angle-data transmitter. 3. Experimental 3.1 Geometry of anisotropic textile shell The initial information obtained from the punch deformation process is dependence H-P. Parameters H, P and the angle of curve slope (stiffness coefficient) in these plots vary within the application of different punches (R = const). Similar to the case of uniaxial tension, the zones of zero stiffness in these curves are significant and run from 23 per cent up to 40 per cent of highest possible deflection value Hmax after which, steep turn of straightening appears (Figure 2). It was determined that the whole family of punching H-P curves can be described with sufficient tolerance (r2 = 0.999 7 0.983) by exponential (Equations (1) and (2) or power (Equation (3)) functions. The smallest errors are obtained by the first function: H
1
P ae b ; H
P a be c ;
2
P aH b :
3
The investigations have shown that such parameters of biaxial deformation as deflection height H, tearing force P and the location of punch centre Hc are not stable but vary in respect to the ratio r/R. In the case of K1 material tearing Parameters
K1
K2
Composition
50% cotton 50% viscose Weft-knit ``double'' 161 rib 1.05
100% PE
141.7 81.4
282.7 83.6
97.4 138.9 0.70
106.8 372.3 0.29
Fabric structure
Table II. Characteristics of investigated knitted fabrics
Thickness, mm Specific tensile strength, N/mm wale direction course direction Elongation, % wale direction course direction Coefficient of anisotropy
Weft-knit 161 rib 1.00
Textile behaviour in biaxial punch 179
Figure 2. K1 material punch deformation curves obtained by five punches (punch characteristics are given in Table I)
force P increases 3.7 7 4.0 times and specimen deflection height H decreases 7 7 19 per cent when ratio r/R varies in the range of 0.18 7 0.89. It was assumed that some factor describing materials' mechanical properties must exist. Besides, it must be stable for all ratio r/R values, i.e. irrespective of the punch size. Tests have shown that such a factor can be the length of shorter generating line ± l (Figure 3). The length of generating line for the material K1 in the direction of small deformations varied within the limits of 3.8 per cent (from 93.7mm to 90.1mm), i.e. took values in the range of measurement errors. The angle of punch covering b in the direction of the shorter generating line was determined by AutoCAD software. It was observed that in punch deformation process when deflection height was near to critical, i.e. H Hcr , this angle was constant and equalled 168.5ë 3ë.
Figure 3. Spatial shape of shorter generating line of K1 knitted material
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Besides the properties detected earlier (l = const and b = const) it was noticed that the part of the generating line from the point where it loses its contact with the punch up to the clamps can be characterised by one arc. The radii r of this arc decrease when punches of longer radii r are applied (Figure 3). The longer generating line of anisotropic materials is bent more than the shorter. Its shape is more complicated and it cannot be described by one arc. For some very anisotrop materials, e.g. K2 (Table II), this generating line remains almost unloaded. 3.2 Comparative analysis of uniaxial and biaxial punch deformations Punch tests for comparative analysis of uniaxial and biaxial deformations were performed by a special device, using larger specimens (R = 49 mm, A = 75 cm2) and two spherical punches different in material (glass, steel), size (r1 = 48 mm, r2 = 30 mm) and mass (m1 = 1,255g, m2 = 912g). The principal scheme of the punch test is shown in Figure 4. Here a disc shaped specimen is clamped in horizontal jaws and loaded free by punch or by the additional load. The latter depends on the masses of holder (mh) and weight (mw). The sum of masses mr + mh + mw guarantees a wide spectrum of experimental regimes. In fact, this test may be considered as a creep test providing creep curve H-t. The results of tested fabrics' behaviour in biaxial punch and uniaxial tensile tests are given in Table III. As expected, elongation eS in a less stretched direction compared with its diameter varies by 20.9 7 42.9 per cent, depending on fabric type and punch size. Table III shows that linear strains in both cases of deformation (the same loading intensity s = 0.3N/cm and s = 0.4N/cm and base length l = 2R = 99 1mm) are not equal but similar. For example, sufficiently high correlation coefficient r2 = 0.91 between deformations of shorter generating line and uniaxial elongation in the corresponding direction for knitted fabrics illustrates their high linear association. So, the deflection height H in punch deformation does not characterise the tensile properties of an anisotropic specimen, because load affects only the
Figure 4. Principal scheme of punch creeping test
more stiff thread system, while perpendicular direction is not loaded or loaded insignificantly. Thus, the concept of generating lines must be used in anisotropic materials' punch deformation. The values of emin and emin strains locate on these axes. Hence, these points may be connected by a curve described as elliptical or oval (Figure 5). In the case of isotropic fabric, punch load will be equally distributed in two principal directions or thread systems. So the intensity of loading will decrease twice compared with uniaxial deformation but in the case of highly anisotropic elastic fabrics only one thread system is affected by punch load, the other remaining almost unloaded. The investigations of knitted material punch deformation revealed that highly stretchable and anisotropic materials often experience a state of uniaxial tension and form a thin non-rotation surface with one ``soft'' generating line. Thus, besides the deflection height H we propose to use more precise criteria for the evaluation of textiles deformation behaviour, that is the length of generating line l and their curvature r, which reveal the non-uniformity of stress and strain distribution. As was noted earlier, maximum stresses smaxconcentrate on the line of fabric separation from punch. Receding from this line, stresses decrease in both directions, i.e. in the direction of the jaw because of perimeter increase and in the direction of the punch centre due to friction. Concerning geometry simulation, experimental conditions must be close to service conditions; thus ratio r/R & 1. The application of short radii punches does not simulate the clothing wearing process, because it relates to specimen puncture. The increase of ratio r/R increases the punch and specimen contact surface, the result of which is the growth of friction force between punch surface and specimen. The latter stems the deformation process and significantly shortens the length of the distortion zone. Therefore it may cause essential differences between the uniaxial and biaxial processes.
Textile behaviour in biaxial punch 181
3.3 Effect of friction in punch deformation The peculiarities of punch deformation are hard to explain on the basis of a textile system, because the structure units of a textile ± yarns or threads ± in biaxial deformation remain in a state of uniaxial tension. For this reason it is proposed to examine the behaviour of homogeneous material such as
Fabrics K1 K2
Biaxial deformation H, mm es**,% r1 r2 r1 r2 29.5 39.5
31.5 46.0
20.9 37.7
21.3 42.9
Strains in uniaxial deformation e, % Pmin* being equal to: 0.4N/cm 0.3N/cm 0ë 90ë 0ë 90ë 64.0 147.0
20.0 38.0
60.0 140.0
18.0 36.0
Notes: Pmin* ± load intensity equal to the weight intensities of heavy r1 and light r2 balls on the clamped contour of the specimen; es** ± elongation in the less stretched direction
Table III. Fabric behaviour in biaxial and uniaxial deformation under the same loading intensity
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Figure 5. Shapes of two perpendicular generating lines of (a) K1 and (b) K2 knitted fabrics.
polyethylene membrane. The crystallinity of the polyethylene membrane is considerably high (60-95 per cent) and it has a comparatively stable and simple structure. In punch loading its crystalline structure that is made up of spherulites (20-500+), turns into a fibril structure orientated in a deformation direction (Tijuneliene et al., 1999). To analyse the effect of friction factor in punch deformation structural investigations were performed by the X-ray diffraction method using
diffractometer DRON-3 (CoKa radiation, l = 1.785+). The thickness of samples was controlled by thickness gauge. The object of the investigation was polyethylene membrane PE (thickness d = 0.24mm) processed by the extrusion blowing method. Its characteristics in longitudinal (l) and transverse (t) directions were as follows: ty = 2.0 0.1N/mm; ly = 2.2 0.1N/mm; lcr = 3.6 0.2N/mm; tcr = 3.7 0.1N/mm; "ty = 80.0 0.4 per cent; "ly = 80.4 5.1 per cent; "tcr = 468.0 32.4 per cent. "lcr = 500.0 40.8 per cent;
Textile behaviour in biaxial punch 183
After punch loading a thin walled shell with two evidently different zones is formed. The middle part of the shell is a clearly thinned neck zone, while the top and the edge of the shell remain almost unchanged. Figure 6 presents the location of points where the thickness of the specimen was measured. It can be clearly seen that the edge (position 4) and the top zones (position 3) of the shell remain almost unchanged. In these zones the specimen becomes thinner only by 3 7 5 per cent. The part of the neck in contact with the punch (positions 1' and 2') becomes less thin in comparison with the rest of the neck below the contact line (positions 1 and 2) because of friction between the shell and the punch. The difference takes values in the range D = 0.2 to 2.9 per cent (Figure 6). Hence, the shell formation in cold conditions shows evident asymmetry of the deformation characteristics and related geometry of the formed shell. Besides the membrane thickness changes the effect of friction may be observed on some other mechanical and structural parameters. The analysis of punch deformation data showed essential differences in the character of deformation curves H-P after lubrication of the interlayer between punch and specimen. The initial part of curves remained unchanged up to yield point except their slope angle which varied in the range of a = 80 2ë. Significant changes occurred beyond the yield point. Vivid changes in the curves between the yield and tearing points prove that the yield zone and shell ``neck'' become shorter after specimen lubrication.
Figure 6. Changes in PE membrane thickness d at different points of its shell after punch deformation
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The effect of specimen lubrication may be observed from the plots of typical Xray spectra in Figure 7. Specimens were taken from the top zone of the shell. Here the changes of both polyethylene typical reflex intensities are vivid, i.e. reflex 110 intensity decreases, but the intensity of 200 reflex significantly increases. This experimental evidence proves that specimen deformation provokes polyethylene crystallinity failure. The magnitude of changes is approximately proportional to the deformation level. X-ray spectra analysis showed that the initial crystallinity of the tested specimens was 73 per cent, ratio of main 110 and 200 intensities I110:I200 = 5.9:1 and crystal size ± 306 +, respectively. Hence, all analysed cases of thin shell formation from the polyethylene membrane evidently proved a significant decrease in the crystallinity parameters (Table IV). However, this decrease depends on the friction between punch and specimen and the location of the tested sample.
Figure 7. Typical X-ray spectra of PE 0,24
Type Table IV. The results of X-ray spectra analysis
0 1 1L
Crystallite size, +
Intensities ratio (I110/I200)
Crystallinity, %
306 253 204
5.9:1 4.2:1 1.3:1
73 62 59
4. Conclusions Biaxial deformation methods compared with uniaxial tension have several features. The first ± stress concentration near the punch, i.e. at the centre of the specimen, that determines close distribution of measurement results, minor errors and lower number of testing samples, needed for statistical reliability. The second is the ability to simulate certain technological conditions, e.g. moulding, where forces imposed on the fabrics cause a biaxial stress state. The results show that the anisotropic shell formed in the punching process has a complicated geometry that does not confirm the earlier presumption about rotation surfaces. Such parameters as the length of generating line l and the radii of generating line arc r are suggested in order to specify the geometry of the shorter generating line. Punch deformation is complicated by friction at the contact zone of the specimen/punch. Deformations there are small and stresses locate at the line where the specimen loses its contact with the punch. X-ray diffraction analysis showed that after the application of a dry (high friction coefficient) punch the structural changes at the top of the shell are negligible compared with the structural changes after the application of a lubricated (low friction factor) punch. In this case crystallinity at the top of the shell decreases from 73 per cent down to 59 per cent, ratio of reflex intensities I110 : I200 from 5.9 : 1 down to 1.3 : 1 and crystallite size from 30.6 + down to 20.4 +, respectively. References Daukantiene, V. and Gutauskas, M. (1998), ``The influence of clamps geometry on polymer membranes punch deformation characteristics'', Proceedings of the Conf. Design and Technology of Consumer Goods, Kaunas, Lithuania (in Lithuanian), pp. 201-05. Flerova, L. and Surikova, G. (1972), ``Materials science of knitted fabrics'', Liokhkaja Industrija, Moscow (in Russian). Kawabata, S. (1989), ``Non-linear mechanics of woven and knitted materials'', Textile Structural Composites, Elsevier Science Publishers BV, Amsterdam. Kisilak, D.A. (1999), ``New method of evaluating spherical fabric deformation'', Textile Research Journal, Vol. 69 No. 12, pp. 908-13. Kobliakov, A. (1973), ``Structural and mechanical properties of knitted materials'', Liokhkaja Industrija, Moscow (in Russian). Kuprijanov, M. (1969), ``Deformational properties of footwear outer leather'', Liokhkaja Industrija, Moscow (in Russian). Strazdiene, E., Gutauskas, M. and Williams, J.T. (1997), ``Mechanical behaviour prediction of spatial textile constructions'', Proceedings of 2nd International IMCEP'97 Conference, Maribor, Slovenia, pp. 71-9. Tijuneliene, L. and Gutauskas, M. (1998), ``The geometry of punch formed thin shell and method of its determination'', Proceedings of the Conf. Design and Technology of Consumer Goods, Kaunas, Lithuania, pp. 194-200. Tijuneliene, L., Strazdiene, E. and Gutauskas, M. (1999), ``The behaviour of polyethylene membrane due to punch deformation process'', Polymer Testing, No. 18, pp. 635-40.
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Use of a knowledge base for studying the correlation between the constructional parameters of fabrics and properties of a fused panel Simona JevsÏnik and Jelka GersÏak
Faculty for Mechanical Engineering, Institute of Textile and Garment Manufacture Processes, University of Maribor, Maribor, Slovenia Keywords Clothing, Fabric Abstract The mechanical and physical properties of fusible interlinings and fabrics depend on their constructional parameters, but fused panel properties depend on all of them. A new approach is presented for analysing the dependence of the constructional parameters of fabrics on the properties of fused panels. This study was carried out on the basis of a knowledge base for predicting the formability of fused panels made from wool fabrics suitable for upper clothes. This knowledge base was constructed using program package RETIS for machine learning from examples. This knowledge was presented in the form of regression trees. Using regression trees it is possible to predict the properties of a fused panel as well as to analyse the influence of parameters on the properties of a fused panel. Furthermore the results of analysis gained by regression trees were compared and confirmed using experimental measurements.
International Journal of Clothing Science and Technology, Vol. 13 No. 3/4, 2001, pp. 186-197. # MCB University Press, 0955-6222
1. Introduction Before designing clothes fabrics have to be chosen. The construction parameters of fabrics define their mechanical properties, i.e. extension, shearing and bending rigidity. Often fabrics do not have the required properties in order to construct the clothing parts and therefore suitable garments in a desired form or shape cannot be made. These properties could be improved by fusing using fusible interlinings and the result of this is a fused panel. The fused panel arises during the fusing process as a joined composite between the fabrics and the fusible interlining. The properties of a fused panel have specific values with respect to the shell fabrics and fusible interlinings, and for this reason when selecting the fusible interlining it is necessary to know the properties of the fusible interlinings as well as the fabrics. Previous research work has concentrated on studying the influence of the kinds of fusible interlinings and parameters of fusing processes on the properties of a fused panel. However, the properties of a fused panel can also be expressed using the properties of the fabrics (JevsÏnik, 1999). The aim of this contribution was to study the correlation between the construction parameters of fabrics and the properties of fusible interlinings. In order to study this problem the knowledge base was used presented as regression trees. The
regression trees were constructed using program package RETIS for machine learning from examples. 2. The influence of the constructional parameters of the formability of a cloth On the basis of interacting the fusible interlinings and the fabrics are defined as the properties of a fused garment part (JevsÏnik, 1999; JevsÏnik, and GersÏak, 2000). The shell fabrics are chosen according to the fashion of the garment, but the fusible interlining is that component which changes the properties of fabrics after the fusing processes. Therefore the fused panel is not dependent only on the kind of fusible interlining but on construction parameters too. A fabrics construction is defined by the following parameters (ZÏibernaÏSujica and PintaricÏ, 1997): .
.
Fibre structure and its properties (fibre type; fibre mixture; geometrical, physical, mechanical and chemical properties); Yarn structure and its properties (yarn type; geometrical, physical, mechanical and structural properties; technological parameters of spinning);
.
Fabric geometry (weave, density, working-in, weight);
.
Fabric patterning;
.
Technology of fabric production.
In the narrower sense of the meaning the constructional parameters refer to fabric structure. Furthermore, the structure parameters of fabrics could be divided into primary, i.e. density, weave and linear density, and secondary, which consist of a combination of different primary parameters. These are: working-in, weight, physical and mechanical properties. The primary parameters are dependent variables, because the choice of any one of them has an influence on the size of the others. The primary and secondary parameters define the mechanical and physical parameters of fabrics and the overall expression of formability. The formability of a fabric is the property that tells us if the fabric has the ability to form or adapt to the construction of the clothes. It is directly connected with the bending rigidity of the fabric and is expressed as (Postel et al., 1988): B EI M where: E ± Young's modulus I ± moment of inertia ± radius of bend M ± bending moment
1
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The formability is expressed as a product between bending rigidity B and relative extensibility e by lower load: F B"
2
B ± bending rigidity/mNm " ± relative extension/% The bending rigidity of a fabric is proportional to the product of the Young's modulus of material at the moment of inertia (GersÏak, 1997). The density of fabric is defined as number of warp and weft yarns on the appointed length (see Figure 1). The properties of the fabric depend on the density of the fabric in a warp and weft direction, which is conditioned with the linear density of the yarn. Usually in fabrics with higher density we use finer yarn. The density as well as interacting points are changing according to the weave of the fabric (Hatch, 1999). The higher density at the same weave of the fabric means more interfacing points. Further, a greater number of the interfacing points of fabric means that fabric is more rigid because the yarns are close together. On the other hand, the fabrics with fewer interfacing points have some freedom of movement; therefore these fabrics are less rigid and have a higher degree of formability. 3. Machine learning For human beings the learning process is a natural characteristic and is referred to as nature learning but, if the learner is a machine, i.e. computer, then it is called machine learning (Kononenko, 1997). This method of artificial intelligence concerns the development of intelligent systems which are appropriate for the solution of relatively difficult problems. They are actually based on an imitation of the mental processes of human thinking when solving complex problems. Artificial intelligence is used for solving problems in the following areas: machine learning, computer perception, knowledge representation, natural language understanding, logic
Figure 1. Structural elements of woven fabrics
programming, quality modelling, development of expert systems, game playing, heuristic problem solving, robotic, and cognitive modelling (Kononenko, 1997). From the point of view of engineering practice artificial intelligence represents the development of tools to introduce the knowledge and procedure for automatic problem solving, which only a human could previously perform properly. This engineering approach requires the development of computer programs, i.e. algorithms and databases, which have the capacity for intelligent behaviour. The conventional way of collecting knowledge has been dialogue between artificial intelligence experts and people with expertise in problem domains. This approach is laborious and time-consuming. Machine learning, however, presents an alternative way of constructing a knowledge base. The aim of this machine learning method is knowledge collection but it is not intended for a particular expert system. However, it does present a basic legality from which it is possible to learn the rules and relationships which are needed in any particular domain. 3.1 The knowledge presentation The learning algorithm gives on entry the pre-defined knowledge and learning examples. It then searches across the space of possible hypotheses until it gives a suitable hypothesis. In general there are two types of knowledge presentation (Kononenko, 1997): (1) Structural presentation: The objects are presented with components and the relationships between them. (2) Attributes presentation: Only the properties of objects are described. The most used formulae for presenting knowledge by machine learning are: . propositional calculus; . first-order predicate calculus; and . probability distribution. 3.2 Regression trees An attribute presentation of learning examples with discrete sets is used for the construction of regression trees and each learning example is described using the vector value of attributes. An attribute could be discrete or continuous and their value is the form of a predefined set of values. The interpretation of regression trees is as follows: Each internal node of the tree contains a test on a value of an attribute. According to the results of the test, interpretation of the tree proceeds to the left or right subtree of the node. A leaf prescribes a value to the function, approximated by the regression tree. An example of a decision tree is shown in Figure 2. The basic algorithm could be presented in the following way (Hatch, 1999): If implement the established condition then setting up a leaf which includes all learning examples
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Figure 2. An example of regression trees
else select ``most informative attribute'' attribute Ai denote follower with value of attribute Ai for each value Vj of attribute Ai renew: recursively construct a subtree with corresponding subset of examples Implemented the establish result in condition could be: (1) The learning set is ``clear'' enough, i.e. all or most examples are from the same class; (2) The learning set does not contain enough examples for the prediction from the regression trees to be reliable; (3) In the learning set ``good'' attributes are missing. The decision trees present the classification function, which is a symbolic presentation and summary of all principles in the present problem domain. This is the reason why this tree is interesting for a researcher of given problem domains, because they can choose determination of principles and structure. 4. Methodology The problem area of research was to examine the influence of the constructional parameters of fabrics on the formability of a fused panel using the knowledge base. Conclusions were obtained by analysis of regression trees and verified by experimental measurements. 4.1 Experimental work Using the program package RETIS for machine learning from examples, two knowledge bases for predicting the formability of a fused panel were constructed. One was designated FF-1 for warp direction and the other FF-2 for
weft direction. This knowledge was presented in the form of regression trees, which could be used for predicting the formability of the fused panel as well as to analyse the dependence between particular parameters. The analyses of interdependence between particular parameters in regression trees could be performed using graphical and textual form (see Figure 2). Using a graphical interpretation of the rules we begin at the root of the regression tree and then we simply follow the value in the nodes until we reach the value in a leaf. The path from the root to the leaf of a regression tree presents one of the constructed classification rules. The correlation between the nodes could be used for analysing the influential factors on the properties of a fused panel, i.e. formability. Using textual records, the regression trees could be used to find the degree of correlation among several nodes from a separate node. The following information could be obtained: . The number of examples in a node. . The sum of the weight of all examples in a node. . Information about individual attributes in a node. . Accuracy of the predicted value in a leaf of the regression tree.
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Both regression trees give very good results, when the properties for a new kind of wool fused panel are predicted. This certifies high correlation coefficients: 0.82 for FF-1 and 0.84 for FF-2 between predicted and measured values of new examples of fused panels (JevsÏnik, 1999; JevsÏnik and GersÏnik, 2000). Constructed regression trees distinguish between the kind of attributes in a node, the number of constructed rules and the number of decision nodes (see Table I). Furthermore, on the basis of the analyses of separate regression trees a study of the influence of the constructed parameters of the fabric on the formability of a fused panel is performed (see Figure 3). The statements gained were confirmed using experimental measurements. For this purpose wool fabrics suitable for upper clothes were used. The fabrics had three different weaves: plain weave P 11, twill weave K 12 and twill weave K 22. Within each weave the fabrics had different density, linear density and surface weight (see Table II). Code of regression tree FF-1 FF-2
Name of attributes in a root Linear density of fusible interlining in a warp direction Thickness of fabric
Number of constructed rules
28 21
Number of nodes
29 22
Table I. The basic characteristics of analysed regression trees
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Figure 3. One constricted rule on part of a regression tree for predicting the formability of a fused panel in a weft direction
According to the given statement the fabrics were fused with suitable fusible interlinings. Altogether we used five different fusible interlinings with the following properties (see Table III). The fusing process was carried out on a continuous press machine. The measurements were performed using the FAST system for an objective evaluation of the properties of the shell fabrics, fusible interlinings and fused panels. All measurements were carried out under standard testing conditions (20 2ëC and 65 2 per cent RH). Code of fabric P-1 P-2 P-3 P-4 P-5 P-6 K-7 K-8 K-9 L-10 L-11
Weave P 11 P 11 P 11 P 11 P 11 P 11 K 12 K 12 K 12 K 22 K 22
Yarn density niti/cm go gv 20.64 20.64 27.57 24.11 24.11 23.5 30.91 30.19 30.24 26.34 26.34
18 18 20 18 18 19 21 24 23 24 24
Linear density Tt/tex fo fv 19.23 19.23 19.23 19.23 19.23 19.5 14.29 19.23 14.29 14.29 14.29
19.23 19.23 19.23 19.23 19.23 19.5 14.29 19.23 14.29 14.29 14.29
Surface fabric weight W/gm-2 152 152 149 166 168 150 164 193 207 262 271
Table II. List of fabric properties Notes: go warp density; fo warp linear density; gv weft density; fv weft linear density
Research parameters Raw material Weave Surface fabric weight/gm-2 Warp density/niti/cm-1 Weft density/niti/cm-1 Warp linear density/Tt /tex Weft linear density/Tt /tex Adhesive type Amount/Wt /gm-2
M1
Code of fusible interlining M2 M3 M4
M5
31% PA, 69% CV A 14
58% Co, 42% CV A 14
53% Co, 47% CV A 14
100% Co
100% Co
P 11
P 11
66 11 10 4.4 36 PA 9
110 29 8 20 50 PA 12-14
98 24 8 20 50 PA 12-14
65 17 17 24 10.5 PA 10
85 20 20 24 13 VT PE* 18-12
5. Results Results of our research work are given in the following forms: . Given statement of correlation between the constructional parameters of fabrics and the formability of the fused panel from regression trees. . The results of experimental measurements for the confirmation of given statements. 5.1 The analyses of regression trees The study of the influence of construction parameters on the formability of a fused panel was performed from constructed rules, which were presented in graphical and textual form. From the analyses of the regression trees the following statements can be given: . Statement 1: When increasing the density of fabrics in a warp and weft direction, the formability of the fused panel reduces if the linear density is equal. . Statement 2: The variation of weave in a fabric has an indirect influence on the density of shell fabrics in a warp and weft direction. At the same time the formability of the fused panel also varies. . Statement 3: The surface weight of fabrics has an essential influence on the formability of the fused panel in a warp as well as a weft direction. 5.2 The results of experimental measurement The results of experimental research for confirmation of given statements are given in the form of measurements of formability of fused panels in a warp and weft direction according to the changes of density of the fabric (see Figures 4 to 7), and regarding the weight of fabrics at different weaves (see Figure 8). 6. Discussion The results of our experimental analyses confirm the statements given from our study of regression trees and they can be as follows:
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193 Table III. List of fusible interlinings properties
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Figure 4. Formability of fused panels in a warp direction fused with interlining M2 regarding the density at the equal linear density of fabric in the plain weave
Figure 5. Formability of fused panels in a weft direction fused with interlining M2 regarding the density at the equal linear density of fabric in the plain weave .
.
Statement 1 was confirmed on the basis of the results from Figures 4 and 5, which showed that with equal weaves of the fabrics by equal linear density the formability of the fabric as well as of the fused panel is changed, if the density of the shell fabric changes. The results from Figures 6 and 7 confirm Statement 2. Therefore it can be concluded that the variation of weave of the shell fabric is connected with the variation of the density of the fabrics and that it has an influence on the formability of a fabric as well as the fused panel, even though the linear density is equal. So the fused panel made from fabrics in a plain weave has less density and so a lower value of formability in a warp and weft direction.
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195 Figure 6. Formability of fused panels in a warp direction fused with interlining M1 regarding the density and weave of fabric at the equal linear density
Figure 7. Formability of fused panels in a weft direction fused with interlining M1 regarding the density and weave of fabric at the equal linear density
Figure 8. Formability of fused panels according to different surface weight using three different weave of fabrics
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.
Twill fabrics usually have higher density and so a higher value of formability than plain fabrics. The rules constructed in regression trees show explicit dependence on surface weight according to the density, linear density and weave of the fabrics. The surface weight is mostly represented when deciding attributes by both regression trees, namely nine times in regression tree FF-1 and five times in regression tree FF-2. From this it could be concluded that the formability of the fabrics as well as the fused panel is dependent on surface weight. Furthermore this statement also confirmed the results from Table IV, which presented the variable analysis for establishing the influence of the surface weight on the formability of fused panels. We can conclude that the surface weight of fabrics has a significant influence on the formability of fused panels, irrespective of the kind of fusible interlinings used.
7. Conclusion To achieve the desired silhouette during the construction and planning of a garment, the kind and quality of both the shell fabric and the fusible interlining must be harmonised. Wide expert knowledge is required for searching the Code of fused panel F-M1
F-M2
F-M3
F-M4 Table IV. The results of the surface weight influence of fabrics on the formability by variable analysis
F-M5
Weave Calculated parameters of MSwg MSbg Fizr Ftab(a = 0.05) Significant fabric Warp Weft Warp Weft Warp Weft Warp Weft Warp Weft P 11 K 12 K 22 P 11 K 12 K 22 P 11 K 12 K 22 P 11 K 12 K 22 P 11 K 12 K 22
0.01 0.02 0.06 0.09 0.13 0.08 0.23 0.24 0.26 0.06 0.07 0.09 0.05 0.08 0.28
0.01 0.01 0.01 0.01 0.04 0.06 0.04 0.05 0.07 0.06 0.09 0.02 0.02 0.13 0.10
0.10 0.15 2.31 0.87 1.24 0.78 1.97 1.72 3.08 0.93 1.68 2.18 0.59 1.89 3.71
0.42 0.22 0.14 0.65 2.40 0.88 0.69 1.12 1.13 0.46 1.43 0.65 1.29 2.89 2.07
9.81 9.08 41.13 9.52 9.41 9.84 8.63 7.12 12.01 15.18 23.05 25.43 12.79 22.70 13.70
51.75 20.84 15.09 52.83 54.40 13.90 16.73 21.89 15.60 7.77 16.21 28.87 52.48 22.05 20.13
4.76 5.10 7.57 4.76 5.10 7.57 4.76 5.10 7.57 4.76 5.10 7.57 4.76 5.10 7.57
4.76 5.10 7.57 4.76 5.10 7.57 4.76 5.10 7.57 4.76 5.10 7.57 4.76 5.10 7.57
Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Notes: MSwg ± Mean square within group; MSbg ± Mean square between groups
Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
interaction between all influenced parameters on the properties of fused panels. This method of machine learning from examples provides a successful technique for predicting the properties of new examples of fused panels. However, this contribution presented the new accession to study the construction parameters of fabrics according to properties of fused panels. Given the results shown, it could be possible to use the same regression trees which predict the properties of fused panels, also to carry out analyses of the parameters that have a significant influence on the properties of fused panels. In our case the constructed regression trees are limited only to wool fabrics for upper clothes; therefore we were limited in giving the statements. To add new examples to a database would indicate a new dimension for research work in this area, where we could expect a lot of interesting conclusions from the unknown. 8. References GersÏak, J. (1997), ``Objective evaluation of heat-set garment parts'', Tekstil, Vol. 46 No. 4, pp. 193-203. Hatch, K.L. (1999), Textile Science, University of Arizona Tucson, Tucson, AZ. JevsÏnik, S. (1999), ``The selection of fusible interlinings and a prediction of the properties of fused garment parts with knowledge system'', Master's thesis, Faculty of Mechanical Engineering, University of Maribor. JevsÏnik, S. and GersÏak, J. (2000), ``Engineering fused panel properties. Using the knowledge system'', 4th International Conference TEXSCI 2000, Liberec, pp. 348-52. Kononenko, I. (1997), Machine Learning, University of Ljubljana, Ljubljana. Postel, R., Carnaby, G.A. and de Jong, S. (1988), ``The mechanics of wool structures'', Commonwealth Scientific and Industrial Research Organization, Ryde, New South Wales. ZÏiberna-SÏujica, M. and PintaricÏ, A. (1997), ``Numerical evaluation of fabric construction parameters'', International Conference Innovation and Modelling of Clothing Engineering Processes ± IMCEP'97, Faculty of Mechanical Engineering, University of Maribor, pp. 248-55.
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A novel algorithm for fitting a woven-cloth to complex surfaces Rajcoomar B. Ramgulam
Department of Textile Technology, Faculty of Engineering, University of Mauritius, ReÂduit, Mauritius Keywords Woven fabrics, Algorithms Abstract A fitting algorithm is presented that can be applied to any surface described numerically or analytically. The algorithm that is based on differential geometry is more robust and faster than the traditional kinetic-model based algorithms and it also allows for more flexible initial conditions.
International Journal of Clothing Science and Technology, Vol. 13 No. 3/4, 2001, pp. 198-207. # MCB University Press, 0955-6222
Introduction Composites have already proven their worth as weight-saving materials. Woven fabrics are by far the most commonly used forms of composites in structural applications. Besides interesting mechanical properties, their ease of handling and their excellent formability make these composites very attractive for parts of complicated or curved shapes. Woven fabrics can undergo important deformations, while maintaining a stable structure and a uniform fibre distribution. Woven fabrics undergo in-plane shear deformation when forced to conform to a surface having double curvature. This deformation, coupled with the kinetics of mapping paths from a flat surface on to a curved surface, makes the prediction of yarn paths on the surface non-trivial. The mechanical properties, such as strength and stiffness, vary from point to point in the finished product, being dependent on the local yarn directions. Other material properties, such as thermal expansion and thermal conductivity, are also a function of yarn directions. An infinite number of fitted fabric configurations is possible for any surface. A method of determining a unique fitted configuration is essential to determine yarn paths. An understanding of the fitting process and the ability to control it are important in determining and controlling yarn paths and continuity and hence the mechanical properties in a formed composite. One of the most serious flaws that arise during forming is wrinkling. Other problems include fibre misalignment and variations in local fibre volume fraction due to fibre spreading. These problems tend to significantly degrade the performance characteristics of the final product. For many shapes one-to-one mapping is not possible and wrinkling will happen. The remedy used in hand lay-up, cutting darts in the material, results in loss of strength. It is also not a practical procedure in the case of automated manufacturing methods.
In-plane shearing is the most important parameter that governs fitting of woven fabrics. As a fabric is fitted on to a surface, shearing occurs increasingly until the critical shearing angle is reached. This limiting angle is the angle achieved just before the onset of puckering or wrinkling. The limiting shear angle is a characteristic of the fabric.
A novel algorithm
Literature survey Many authors have studied the problem of yarn placement and orientation during the forming of complex composite parts. Mack and Taylor (1956) were the first to propose a method for fitting woven fabrics on complex surfaces and they also defined the basic assumptions for woven fabric fitting. Several authors, Robertson et al. (1984), Smiley and Pipes (1987), Bergsma and Huisman (1988), Heisey and Haller (1988), have subsequently proposed modified models for but in most cases the algorithms were limited to particular surfaces for which analytic equations were known. Van West et al. (1990) were the first to consider the fitting of woven cloth to an arbitrary surface that allows any number of draped configurations. To achieve a unique draped configuration one warp and one weft are selected to follow specific paths on the surface; the remainder of the thread paths on the surface are then uniquely determined. Subsequently Aono et al. (1996) proposed a new method for specifying the initial conditions, thereby improving the flexibility of the process. Trochu et al. (1996) proposed a similar algorithm combined with the definition of a parametric surface by dual kriging. The fitting algorithms applied to arbitrary surfaces are all based on the intersection of two spheres, both centred at the two known adjacent cross-over points on the surface. Mathematically this involves solving non-linear equations by numerical methods, for example, the Newton-Raphson's method. This requires iteration and a guess initial point that can lead to failure for some surfaces. An algorithm is presented here that does not require numerical methods for computation and is therefore more robust. It also accounts for more flexible initial conditions. Moreover, since it does not require iterations for computation of nodal points, the algorithm presented here is faster. The model proposed is based on differential geometry.
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Curvature of a polygonalised surface A smooth surface can be represented approximately by a polyhedral surface, for example, a large number of triangular faces, as shown in Figure 1. Calladine (1984) has presented a method for defining the shape of small plane elements that, when assembled together without deformation, approximate the shape of the 3D surface. Any vertex where a number of facets join together can be linked with the Gaussian curvature of the smooth surface at the point through the interpretation:
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Gaussian curvature
angular defect at the vertex area associated with the vertex
1
Angular defect is shown in Figure 2: . Angular defect at a vertex = 2p ± sum of the interior angles of the faces at the vertex. . Area associated with the vertex = one-third of the areas of the triangles meeting at the vertex. Gaussian curvature and angle of shear Calladine (1984) has shown that the problem of mapping a planar surface, such as paper, on to a complex surface can be considered, approximately, as creating a quadrilateral grid of small plane elements on to the 3D surface. The same concept can be applied to a woven fabric that is a plane surface when fitted to a complex one. The grid represents a mesh of the woven fabric and the vertices of the quadrilateral can be viewed as the coordinates of cross-over points of the cloth.
Figure 2. Angular defect
A scheme that is directly relevant for fitting fabrics on complex surfaces is to use rhomboidal tiles to approximate doubly curved surfaces. This is shown in Figure 3. In this case, each facet is a rhombus, and the angular defects are inserted by adjusting the internal angles of the rhombuses. The boundaries of the rhombuses represent the warp and weft of the fabric and the corner points, the cross-over points. The angles that are multiples of q are the degree of shear at the cross-over points. For a surface of positive curvature, the further away a rhombus is from the starting-point of the deformation process, the larger is the angular defect. Angular defect is additive, as deformation proceeds away from a starting-point. Hence the following equation: Angular defect Degree of shear Degree of shear n1 :n2 :K:c2
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2
where: c is the length of the side of each rhombus: K is the change in Gaussian curvature; n1 is the warp number; and n2 is the weft number. Equation (2) is a modification of Equation (1) to take into account the representation of a surface using rhomboidal tiles. The corresponding angles of shear (or angular defect) are as marked on the diagram. If the shear angles are very small, then the area of a rhombus is c2. Otherwise the area of a rhombus is c2.sin (90ë-angular defect). Surface generation The surface is defined by a set of co-ordinate points that lie on the surface. A set of four neighbouring points constitutes a patch. Surface equations within a patch are computed by using the cubic spline interpolation (Anand, 1993). Assumptions for fitting simulation The assumptions for the simulation are the same as those originally defined by Mack and Taylor (1956):
Figure 3. Surface representation using rhomboidal tiles
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.
. .
Yarns are inextensible. A crossing of warp and weft is effectively a pivoted joint. No slippage of warp and weft relative to each other occurs at the pivot points. The smallest radius of curvature on any surface is much larger than the distance between adjacent warp and weft. The warp and weft parts between crossings are straight. The fabric is everywhere in contact with the surface.
Fitting simulation The object of the simulation is to display a draped arbitrary surface and to provide information on yarn directions at all points on the surface. The sequence of events in performing the simulation is as follows: (1) Surface to be draped is selected. (2) Fabric cross-over points on the surface are computed. (3) The draped surface is displayed. The required input is a numerical description of the surface and the directions on the surface of the initial warp and weft. Surface point coordinates are provided. Directions of initial warp and weft are chosen. The point data defining the initial yarns are calculated. These data together with the generated surface equations are used to compute the cross-over points. The surface is then displayed with the fabric superimposed on it. Flowchart in Figure 4 illustrates the algorithm. The simulation generates the fabric nodal locations on the formed surface. These data are then used to obtain the following: . The shape or pattern of the flat fabric required forming the surface that can be displayed and then printed. . Shear deformation angle at all nodal points. . Minimum and maximum shear angles. . Shear deformation energy. . Area of fabric required. . Regions on surface where the fabric locking shear angle is exceeded. . Displays of the formed surface in different orientations. Initial yarn path The orientation of the initial yarn is user-selectable and, in Figure 5, it is set at angle a to the Y-axis. Given a starting-point on the surface and a predefined direction, successive equidistant points on the surface are found as follows:
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Figure 4. Fitting simulation
Figure 5. Layout of initial yarn .
.
The tangent and normal vectors at the known nodal point are used as local co-ordinate axes. The new point is located at a distance, spacing, from the known point along the predefined direction for the warp.
Position vector of the new point on the initial yarn is given approximately, using the Taylor series as follows:
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2 3 2 3 nx x 4 y 5 t :
spacing 0:5:
spacing:Kn :4 ny 5 jtj nz z
3
where spacing = distance between two successive nodal points. Fitting of a surface quadrant The initial warp and weft divide the surface into four quadrants and the fitting of the surface is done one quadrant at a time. The fitting process consists of calculating the coordinates of all warp and weft cross-over points of the woven fabric in contact with the 3D surface. In Figure 6 point Q has known coordinates (x, y, z), then the following are the mathematical steps required to obtain a new nodal point, S, adjacent to Q: 2 3 nx (1) The normal vector 4 ny 5 at (x, y, z) is computed. nz (2) The Gaussian curvature, K, at point (x, y, z) is next computed using the normal vector components and the derivatives at (x, y, z). (3) The Gaussian curvature is then used to calculate the shear angle y:
spacing2 : sin :K:N
4
where angle a has been previously computed or is known; N: number of points already computed along warp 3. Equation (4) follows from Equation (2) discussed above. The coordinates of points P and R are also known: 2 3 xp 4 Position vector of point P : yp 5 zp
Figure 6. Computation of a nodal point
Unit vector PR is then rotated through angle 90 2, about the normal at P to get image vector V. Quaternions are used for the transformation (Anand, 1993). Position vector of new point S is obtained as follows: 2 3 xp Position Vector S 4 yp 5 spacing:V
5 zp
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Comparison of kinematic model and model based on differential geometry Figures 7 to 12 give a visual comparison of a deformed woven fabric on four different surfaces. For all the surfaces there is strong correlation of the yarn paths for both models. The difference in size of the formed surfaces for the two simulations is due to the end conditions being not exactly the same in the two cases. The visual displays of the fitted configurations show clearly the similarity of the two models as far as the results of the simulations are concerned. As the kinematic model is already well established, the visual comparison for a variety of surfaces validates the new model based on differential geometry.
Figure 7. Fitting on a hat-shaped surface ± kinematic model
Figure 8. Fitting on a hat-shaped surface ± model based on differential geometry
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Figure 10. Fitting on an elliptically shaped surface ± model based on differential geometry
Figure 11. Fitting on a hemispherically shaped surface ± kinematic model
Figure 12. Fitting on a hemispherically shaped surface ± model based on differential geometry
Conclusions In this paper a new algorithm has been described to model the fitting of woven cloth on to a complex surface. Visual comparison indicates that the software implemented correctly models the actual fitting of woven fabrics. The algorithm developed is faster and more robust than the traditional kinetic models. Moreover, it allows for flexible initial conditions. References Anand, V.B. (1993), Computer Graphics and Geometric Modeling for Engineers, John Wiley & Sons, New York, NY, pp. 309-13. Aono, M., Breen, D.E. and Wozny, M.J. (1996), ``Fitting a woven-cloth model to a curved surface: mapping algorithms'', Computer-Aided Design, Vol. 26 No. 4, April, pp. 278-92. Bergsma, O.K. and Huisman, J. (1988), ``Deep: drawing of fabric reinforced thermoplastics'', Proc. Int. Conf. CADCOMP, Springer Verlag, Berlin, pp. 323-34. Calladine, C.R. (1984), ``Gaussian curvature and shell structures'', Proc. Conf. Mathematics of Surfaces, Manchester, UK, pp. 179-96. Heisey, F.L. and Haller, K.D. (1988), ``Fitting woven fabric to surfaces in three dimensions'', J.Text. Inst., No. 2, pp. 250-63. Mack, C. and Taylor, H.M. (1956), ``The fitting of woven cloth to surfaces'', J.Textile Inst., Vol. 47, pp. 477-88. Robertson, R.E., Hsiue, E.S. and Yeh, G.S.Y. (1984), ``Fiber arrangements during the moulding of continuous fibre composites. II. Flat cloth to a rounded cone'', Polym. Compos., Vol. 5, p. 191. Smiley, A.J. and Pipes, R.B. (1987), ``Fibre placement during the forming of continuous fibre reinforced thermoplastics'', Technical Paper EM87-129, The Society of Manufacturing Engineers, Dearborn, MI. Trochu, F., Hammami, A. and Benoit, Y. (1996), ``Prediction of fibre orientation and net shape definition of complex composite parts'', Composites: Part A, 27A, pp. 319-28. Van West, B.P., Pipes, R.B. and Keefe M. (1990), ``A simulation of the draping of bi-directional fabrics over arbitrary surfaces'', J.Textile Inst., Vol. 81 No. 4, pp. 448-60.
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Voluminal reconstruction of the bodies applied to the cloth trade Florence Dieval, Daniel Mathieu, Karine Herve and Bernard Durand
Laboratoire de Physique et MeÂcanique Textile, Mulhouse, France Keywords Clothing, Data processing Abstract The clothes industry in the developed countries must generate sufficient value added to justify a higher price than the articles produced in great quantity and at low prices in the countries with good wages. The offer of clothing made to measure, at a reasonable price compared with mass-produced clothing, can constitute an interesting opportunity for the clothes trade. The use of data processing can help to achieve this goal. This assumes that the manufacturer has a virtual model of the customer. This model combined with the knowledge of the behaviour of the support/clothing couple allows the data-processing creation of clothing specific to the customer. It is necessary to have a precise and instantaneous acquisition technique. Whatever the principle of measurement, several sensors are necessary to measure the totality of a human body. The results obtained are then like a scatter plot. Moreover, this scatter plot has a non-uniform density according to the measured zone. The surface reconstruction finds these limits in such a situation. In addition, the voluminal reconstruction allows adaptation to this situation by linking spatially the elements describing the shape of the body. Moreover, the use of tetrahedrons allows a modeling of the deformation of the human body. To adapt to the diversity of the scatter plot a method has been developed called the sculptor method. Initially a triangulation gives the convex shape of the scatter plot. It is necessary to remove the superfluous tetrahedrons. To carry out this operation, this form is produced by spheres whose size is adapted. This makes possible a convex solid, which sticks to the scatter plot. This operation shows that this method allows one to reconstruct a body clothed or not with good fidelity.
International Journal of Clothing Science and Technology, Vol. 13 No. 3/4, 2001, pp. 208-216. # MCB University Press, 0955-6222
1. Introduction In developed countries, the clothes trade must be able to produce clothing made-to-measure promptly. The added value that involves such a process is an opportunity for the clothes trade in the developed countries. Data processing associated with a good knowledge of the behaviour of fabrics can realize this goal. But that supposes that each customer can transmit a virtual mannequin of themselves. This model will allow the data-processing design of clothing. A complete virtual mannequin is made up, on the one hand, by knowledge of the volume of the body and, on the other hand, by the mechanical behaviour of the body under the action of clothing. The topology of the body cannot be determined directly. It is necessary to pass by a phase of measurement of points on its surface. The volume is then reconstructed from the scatter plot. Thus we have been interested at that crucial stage which is the condition of the success of a data-processing chain integrated for the clothes industry.
2. Material Our study is about the voluminal reconstruction of a body from a scatter plot. We use two types of scatter plot. The first type of data are obtained mathematically and described simple volumes like the `` twin wheel '' (Figure 1). In this case the points are regularly distributed. The second type of data come from stereoscopic measurements. They are carried out using one pair of cameras, which allow the measurement of a limited zone of space. The points obtained are well-ordered by using a light structured to help the measurement. But the scatter plot remains unspecified with zones of the bust with missing points (because of hidden surfaces) and zones where the points density is more significant (cover zones of two data acquisitions). The scatter plot used for this study is composed of only two data acquisitions. The first data acquisition is that of the man's front and the second is that of his back. Multiple data acquisitions, giving zones of recovery of points, also justify the global voluminal reconstruction.
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3. Method Two main reconstruction tendencies are developed in the literature. First is surface which is often related to a scatter plot coming from the sampling of a closed surface or a surface corresponding to the graph of a function (Roux, 1994; Farardin, 1993). There are two types of surface reconstruction. The first one is based on a mathematical modeling thanks to functions generally of a polynomial type. In fact these methods do not seem very short, as indicated in the zones where the points are very few. Indeed, the functions are not necessarily representative. In order to determine a function, it is necessary to know enough points. If not, many functions could be appropriate and the choice becomes arbitrary. The second method of surface reconstruction consists of generating triangles passing by the points of the scatter plot. The simplexes are not necessarily triangles but are always plane surfaces. It is the fastest method when the points are ordered following the taking of a measurement. We used this method to validate our data acquisition 3D but it cannot be used to reconstruct all the body (Figure 2). The second approach is the reconstruction known as voluminal. The objective is, in this case, to generate polyhedrons (generally tetrahedrons) to reconstruct a volume. This type of reconstruction is used if the scatter plot is unspecified.
Figure 1. Voluminal reconstruction of a twin wheel
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Figure 2. Surface meshing using the constraint of network order
There are several methods of reconstruction. For example, the method suggested by Choi et al. (1988) uses the inflation principle. A tetrahedrisation is put inside the scatter plot. Then, by simple transformations, the initial tetrahedrisation comes to be plated on the measurement points. This method is close to what occurs during the inflation of a balloon. But it requires the use of a virtual mannequin. In order to adapt to all the digitized bodies, a single mannequin is not sufficient. It would be necessary to have a man mannequin and a woman mannequin, even a child mannequin. If we want to take a measurement in a different position, it is necessary to change the range of mannequins or to be able to modify their position. This makes the method constraining. The method of O' Rourke (1981) and Fuchs et al. (1977) minimizes the ratio of the surfaces, which corresponds to the minimization of the tensions in natural situations. Nor is this applicable in our case. The scatter plot being irregular in places, this method can give strange results. An analysis and a critique of the use of this surface ratio were established by Boissonat (1984). The methods that correspond best to our expectation are those that consist of sculpting the convex envelope to reach all the points of the border. Boissonat (1984) and Veltkamp (1990) developed methods which resemble the realization of a sculpture. From the tetrahedrisation of Delaunay a sequential and reasoned removal of certain tetrahedrons is made. The difficulty lies in the choice of elementary volumes, which must be removed. The two methods differ on this point. According to the study of Veltkamp (1990, 1991), the slowest method is that of Boissonat, which uses the variation of the surface of the tetrahedron to be removed. For this reason we used a method derived from the test used by Veltkamp. This method, like that of Boissonat, is based on a tetrahedrisation of Delaunay. The tetrahedrisation is not a true reconstruction. We must obtain a convex volume including the measurement points. But only certain points will be located on the border of the convex envelope, the others being located inside.
As the tetrahedrisation of Delaunay is a basic stage in many reconstructions, we will briefly describe his principle. 4. Tetrahedrisation of Delaunay VoronoõÈ, at the beginning of the century, managed to show (1908) that it is possible to segment space in convex cells: the ``paralleÂloeÁdres primitifs''. These cells are currently used under the name of elementary polyhedrons. From a scatter plot, it is possible to construct the diagram of VoronoõÈ, i.e. the whole of the convex closed polyhedrons covering space without overlapping. These polyhedrons are, for each point Pi of the scatter plot, the whole of the points P of space, which are closer to Pi than of another measurement point. VoronoõÈ used the Euclidean distance to determine its polyhedrons. Delaunay constructed a tetrahedrisation of the scatter plot by using the duplicate of the diagram of VoronoõÈ. The faces of the tetrahedrisation of Delaunay are thus orthogonal with the faces of the cells of VoronoõÈ. If it is difficult to construct the convex envelope of the scatter plot starting from this property, that is much simpler and rapid by using the criterion of the empty sphere (Delaunay, 1934). This criterion says that a triangulation of the convex envelope of a scatter plot is of the Delaunay type, if the open balls circumscribed to its elements are empty. In fact, if the criterion of the empty sphere is checked for all the configurations of two adjacent tetrahedrons in a tetrahedrisation, then that is a tetrahedrisation of Delaunay (Lemma of Delaunay). The tetraedrisation of Delaunay is generally single. But if several points are cocyclic we will obtain a construction made up also of pentahedrons or others, which can then be decomposed in several ways. The tetrahedrisation of Delaunay enables us to obtain the convex envelope of the scatter plot and the partition of this envelope. It is then necessary to dig this volume to be able to reconstruct the bust. 5. The algorithm of the sculptor In order to choose the tetrahedrons to be removed, it is necessary to calculate a parameter g for each point triplet of the scatter plot. This parameter allows locating the triplet compared with the remainder of the points. The sign of g gives an orientation to the plan, passing by the three points considered. This allows one to make out the interior from the outside of the reconstructed volume. Initially, the absolute value of g is calculated for each triplet of the initial scatter plot. To calculate the value of |g| of a triplet of points (P1, P2, P3), the sphere containing a triangle P1P2P3 in the mediator plan should be considered. The radius of this sphere will be noted as Rmin (Figure 3). Let us move the center of a sphere, passing by P1, P2 and P3, along the normal with P1P2P3 as its centre of gravity. The largest sphere, Smax, which contains only these three points, has a radius Rmax, whose value enables us to calculate |g| for this triplet of points.
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Since
Rmax
Rmin ; 1 j j
consequently, knowing the value of Rmin and Rmax for each triplet of points, it is possible to calculate |g| in the following way: Rmax Rmin j j Rmax The second stage of this reconstruction is the convex envelope construction. For that, it is enough to select all the triplets whose absolute value of g is equal to 1. In this case, the center of the sphere Smax is rejected ad infinitum, on one or another side of plane (P1P2P3). There is thus no point located in one of the half spaces delimited by plane (P1P2P3). Then we determine the whole of all the tetrahedrons that can be removed (Figure 4). That is to limit the number of tetrahedrons taken into account in the iteration phase. The restriction used in our algorithm is the same as that of Boissonat (1984). A tetrahedron is regarded as being able to be removed when it is located on the border of the volume (on this step of the reconstruction, the volume is the convex envelope of the scatter plot). They must also answer some additional conditions. It is possible to classify these tetrahedrons in two categories. The first one consists of the tetrahedrons having a face on the border and whose top opposed to the face located on the border is not itself on the border. The second category is formed by the tetrahedrons, having two faces on the border. They must also have the side opposed to the two faces on the border apart from the external envelope of volume in construction. The tetrahedrons with three faces on the limit will obviously not be removable any more. If such a tetrahedron were removed, the common point of the three faces located on the border would be found then on the outside of the volume and the reconstruction could never be achieved.
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Figure 4. Reconstruction by the algorithm of the sculptor
For each triplet of points, we have already calculated the value of |g|. On the other hand, the sign is not known. It is then necessary to calculate it for all the faces of the tetrahedrons, which can be removed in order to determine then that which will be dug. The determination of the sign of g depends on the position of the sphere, Smax. If this centre is located inside the present volume, then the sign is negative; if not it is positive. Once the signs of g are known, the tetrahedron to be dug in first is that with the greatest value of: X
1 faces located on the border
This tetrahedron, if it can be removed, will be dug, i.e. it will be suppressed from the list of the tetrahedrons removable. The faces of the tetrahedron that were not on the border will be dug, as well as the points. Finally, for the close tetrahedrons we start the same removable process again. 6. Results By basing on the theoretical study we developed a data-processing program of voluminal reconstruction. It was initially tested on simple forms obtained by revolution. If the first results were not correct, the modification of certain parameters gave encouraging results (Figure 1). These parameters result from numerical calculation and it is not always easy to regulate them. The algorithm principle requires the determination of
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Figure 5. Scatter plot used to test the parameters of adjustment
the position of the points compared with a plane, a triangle, a sphere, a tetrahedron. The calculation of these positions requires the adjustment of a parameter and sometimes of several. Indeed, the position of a point M of space compared with a plane is determined by inequations utilizing 0. However, from the data-processing point of view, the concept of nullity is determined in an e close. This value corresponds to the round-off errors and the precision of calculations. The point position compared with a plane is thus less precise. It is necessary to choose a value of e which will not result in an aberrant rebuilding. The validation of the program was then made with a scatter plot measured on a man. There were two possibilities of obtaining these data. The first consisted of making two data acquisitions to have the front and the back. The other alternative consisted of taking three data acquisitions that overlapped. The program of reconstruction would thus have been tested with zones where the density of points was higher. In this case, two types of difficulties were joined together: zones without point (neck and low area of the bust) and zones of overlapping. We thus preferred to be confronted with a single difficulty and chose to test the algorithm on a cloud corresponding to two data acquisitions whose points of view are opposite (Figure 5). The algorithm of reconstruction is then tested under difficult conditions and we expected to have errors on the zone, which separates these two data entries. The best reconstruction obtained is not completely exact (Figure 6). The most significant defects appear under the arms. It is connected to the lack of information, which exists following the taking of a measurement. Apart from these zones the tetrahedrons which remain in the volume of the bust are completely satisfactory. It still remains to improve the calculating time of a reconstruction. Although it is not our first objective, we sought to reduce this time. We cut out our scatter plot in horizontal sections and we reconstructed each section separately. Then it is enough to amalgamate all the sections. But this method is not adapted to all digitalizations. It is necessary that each point is ordered according to parallel planes.
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215 Figure 6. Voluminal reconstruction of the bust
The difficulty of this operation is in gathering the sections. Fictitious points have been introduced, in a horizontal plane, above and below each section. These points allow one to have a closed scatter plot and to know which are the tetrahedrons to be deleted in the fusion of the sections. 7. Conclusion To carry out a true CAD for the clothes industry, some determining elements have been developed in the field of the behaviour of the fabrics as well as in the data acquisition of the human body. The data acquisition is the first chain link which will lead to the ``retrodesign'' of a new envelope of the body, clothing. However, it is an illusion to think that one can reconstruct into a surface a human body from two data acquisitions in opposition, which leave zones, some where the density of points is low and others, where the density of points is strong. This is why we studied a voluminal reconstruction called the sculptor starting from the convex polyhedron including the scatter plot resulting from the data entry. This technique allowed one to obtain encouraging results. Now, it could only be used as complementary to the surface reconstruction. However, the morphological laws related to surfaces would also allow one to add points by interpolation in zones inaccessible to data entry. References Boissonat, J.D. (1984), ``Geometric structures for three-dimensional shape representation'', ACM Transactions on Graphics, Vol. 3 No. 4, pp. 266-86. Choi, B.K., Shin, H.Y., Yoon, Y.I. and Lee, J.W. (1988), ``Triangulation of scattered data in 3D space'', Computer Aided Design, Vol. 20 No. 5, pp. 239-48. Delaunay, B. (1934), ``Sur la spheÁre vide'', Bulletin of the Academy of Sciences of the USSR VII: Classe des Sciences MatheÂmatiques et Naturelles, pp. 793-800. Favardin, C. (1993), ``DeÂtermination automatique de structures geÂomeÂtriques destineÂes aÁ la reconstruction de courbes et surfaces aÁ partir de donneÂes ponctuelles'', TheÁse de l'Universite Paul Sabatier de Toulouse. Fuchs, H., Kedem, Z.M. and Uselton, S.P. (1977), ``Optimal surface reconstruction from planar contours'', Communications of the ACM, Vol. 20 No. 10.
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O'Rourke, J. (1981), ``Polyhedra of minimal area as 3D object model'', Proceedings of the International Joint Conference on Artificial Intelligence, pp. 664-6. Roux, J.C. (1994), ``MeÂthodes d'approximation et de geÂomeÂtrie algorithmique pour la reconstruction de courbes et de surfaces'', TheÁse de l'Universite Joseph Fourier, Grenoble. Veltkamp, R.C. (1990), ``The g-neighborhood graph'', Technical Report, CS-R9034, CWI. Veltkamp, R.C. (1991), ``2D and 3D object reconstruction with the g-neighborhood graph'', Technical Report CS-R9116. VoronoõÈ, G. (1908), ``Nouvelles applications des parameÁtres continus aÁ la theÂorie des formes quadratiques'', Recherches sur les paralleÂloeÁdres primitifs'', Journal Reine u. Angew. Math., Vol. 134, pp. 167-71.
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Links between design, pattern development and fabric behaviours for clothes and technical textiles
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Hartmut RoÈdel, Andrea Schenk, Claudia Herzberg and Sybille Krzywinski Dresden University of Technology, Dresden, Germany
Keywords CAD, Simulation, Garments, Textiles Abstract Shows the necessity of developing powerful 3D CAD-systems for the textile and clothing industry. The connection between 2D and 3D CAD-systems enables the user to prepare a collection more quickly and accurately. Applications could be the drape behaviour of the fabric, the deformational behaviour of fabrics when covering defined surfaces and also technical textiles.
1. Introduction The stage of product development and product preparation of clothes requires approximately three times the stage of consumption. In order to compensate for the resulting greater efforts in the product preparation and to react more quickly and flexibly to the latest fashion, the use of complex CAD ± CAM solutions is a must. Today there are lots of existing design programs with various software tools and a wide choice of designing functions. Connected with sketchingsystems so-called two-and-a-half-dimensional presentation programs can give an optical impression of how the colours, motifs and materials look on a scanned model. Steps in production preparation such as pattern construction, grading system, pattern planning and pattern optimisation and the automated cutting are realised by computer assistance. However, CAD-systems available on the market show the following weak spots: . the systems work only two-dimensionally. . the material behaviour and the material parameters are not taken into account. Both these aspects are required for the three-dimensional display of a model with regard to the draping in order to give the designer and model maker a real impression of the model. Optimal possibilities of examing the correct fitting and the form of a model would be the three-dimensional display of a twodimensional pattern construction on a dummy or the development of a threedimensionally constructed model into the two-dimensional level, when the specific material parameters are taken into account. Therefore, the more detailed treatment of physical and mechanical properties and their correct mathematical and physical formulation is of interest.
International Journal of Clothing Science and Technology, Vol. 13 No. 3/4, 2001, pp. 217-227. # MCB University Press, 0955-6222
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2. Three-dimensional display of two-dimensional pattern The current procedure to create patterns is a multi-step approach, which involves too many personnel, too much time and costs due to the trial and error phase. The fabric properties enter the design process only via the expertise of the designers. It is absolutely necessary for CAD-systems to be extended with material parameters and to search for possibilities of connecting design and pattern construction in the future. The objective of the research is to create a complete CAD-system for garment manufacturers including 3D-visualization of garments on virtual human beings. An excellent CAD-system for the clothing industry should comprise the following modules: . fabric library relating easy to determine fabric properties to fabric drape configurations; search and sorting routines should be integrated in the library for easy use; . model for the human body, which can be adapted for persons of different sizes; . routines to simulate garment patterns from specific fabrics on the human body with use of data from the fabric library. The following figures, which were made using DesignConcept 3D by CDI Technologies Ltd (recently belonging to Lectra SysteÁmes, France), give an impression of this subject. The software DesignConcept 3D is based on the polygon computation of NURBS (Non-Uniform-Rational-B-Splines). It is considered the state-of-the-art computation method to design complex polygon surfaces. Figure 1 shows a comparison between the drawing of a designer and the simulated skirt. In this program the bending properties in warp and weft direction, the tensile properties in warp, weft, 45ë warp and 135ë warp direction and also the weight per unit are considered in the draping module.
Figure 1. Comparison of the sketched and simulated skirt
The scale of the property curves depends on the measurement devices (for Clothes and example, KES-FB, Cantilever, Zwick) (see Figure 2). technical textiles A prerequisite for the simulation process is the two-dimensional pattern pieces. They can be prepared with conventional 2D CAD-systems (see Figure 3). Companies have developed 3D body-scanners where the three-dimensional perception of the human body can be realised with a sensor system in a fast and 219 objective way (Figure 4). The DesignConcept 3D enables the user to seam 2D pattern pieces together and drape them over a 3D model. Therefore it is necessary to prepare the 2D pattern piece. Guidelines are used to anchor special lines (for example neckline, waistline) to the 3D body and seam points match different pattern pieces (Figure 5). The next step is to place the 2D-mesh into the 3D space near the 3D body, from which the draping process starts (Figure 6). After this from the draped mesh the user has to generate a surface. The surface can be covered with different colours and/or designs. Figure 7 shows different examples.
Figure 2. Fabric properties
Figure 3. Two-dimensional pattern
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Figure 4. Human body
Figure 5. 2D-pattern with guidelines and seams
Figure 6. Start position
A disadvantage is the high and expensive hardware demands and long calculation times (in some cases up to some hours). Therefore it is necessary to develop those tools with high functionality and with low configuration demands and price and also easy handling. 3. Fit optimization for close fitting garments In the mechanical consideration of deformability of fabrics, on principle, two directions are distinguished. The first deals with drape behaviour of the fabric
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221 Figure 7. Examples of draped surfaces
(chapter 2) and the second is the deformational behaviour of fabrics when covering defined surfaces. This application requires a nearly wrinkle-free draping of the fabric, as, for example, close fitting garments. For close-fitting garments like underwear, sportswear and swimwear, there are high standards of fit and therefore also of pattern construction. The garment size has to be adjusted exactly to the human body, while in optimal comfort wearing and freedom of movement have to be secured at the same time. In pattern construction for close-fitting elastic clothing usually the girth measurements of the garment are constructed so as to be smaller than the body measurements, so that wearing will extend the material. Consequently, not only body measurements, but also the mechanical properties of the fabric crucially influence the garment's fit. Here, the extensibility, i.e. the force-extension relation in case of tensional strain with the corresponding modulus, is a significant material parameter (see Figure 8). Investigations into the wearing strain on knitted clothes showed that the wearing comfort is optimal when stretching the material in girth direction at
Figure 8. Force-extension relation
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Figure 9. Curves on 3D surfaces
1.5 to 2N per 5cm fabric width (for example, underwear) but it is also possible to use other tensile force values (for example, for clothes with a high pressure effect). With the help of a powerful software the designer is in a position to create accurate an 2D pattern from 3D model surfaces for close fitting body shapes. Problems which are characterised by large deformations may be described by incremental formulations to determine the state of deformation and tension stress. For this purpose, a mesh is generated on the component surface to be shaped. The mesh may be generated automatically or interactively. The accuracy of computation depends on the triangle size. Material behaviour is attributed to the mesh to simulate the development in the two-dimensional level depending on the material type. First, you have to draw UV-curves (curves on surfaces) directly on surfaces or create them via Converters functions. UV-curves cannot be drawn across surface boundaries, however. When you modify the surface, any UV-curves on the surface change too (see Figure 9). With the region function it is possible to create accurate 2D pattern pieces from 3D model surfaces. Regions in 3D grow over model surfaces, confirming to surface contours and crossing the boundaries of adjacent surfaces as directed. Once a 3D region is created on a surface model, it may be ``flattened'' to produce a 2D region counterpart (see Figure 10). The next step is to apply the mechanical properties for the knitted fabric to a 3D region mesh. The simulation process is an advanced flattening technique that determines deformation strain and stress and develops a mesh from 3D to 2D based on the mechanical properties applied in the grain and crossdirections. The stress or strain analysis colours show the 3D mesh stress or strain based on the development status of the 2D mesh (see Figure 11). In terms of visualisation, you can apply material properties and maps to regions in order to enhance the realistic appearance of a model. For example, if you apply a patterning fabric image to a 2D pattern, the ``stripes'' appear on the
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Figure 10. Regions on surfaces
Figure 11. Flattening process
associated 3D surface just as they appear on the pattern, regardless of the orientation of the 3D surface (see Figure 12). 4. Technical textiles Lightweight structures including textile construction methods offer definite advantages for the development of curved structural elements, in particular, in the automobile and aircraft industry. This is achieved when textile reinforcing structures, which can be arranged and combined very flexibly, are specifically draped. Owing to the insufficient design experience and the largely high material cost, the potential fields of application, in particular, in the mechanical engineering and the car industries have not been opened up at all.
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Figure 12. Visualisation of the realistic appearance
At present, after the structural element has been designed, the desired design variant is implemented in several iterations. As a result, the development of the structural element most frequently takes a rather long time and involves considerable costs as well. In order to guarantee the required variety of models and to make the structural component adequate to load without at the same time increasing the involved time for industrial engineering, the development of efficient tools for product simulation is of predominant importance. Since 1997 a research team supported by the German Research Foundation (DFG) has been working at Dresden University of Technology under the headline Textile Reinforcements for High-Performance Rotors in Complex Applications. 4.1 Textile preform The following steps are necessary to make a textile preform with the component design being very complex: . pattern design in accordance with material behaviour; . cutting; . stacking; . prefabrication and placing of the z reinforcement; and . assembly of the 3D preform. Most of the components may be produced using various procedures. Material considerations, design and economic aspects should determine the procedure chosen. 4.2 Pattern construction under consideration of the material behaviour If curved element contours of lightweight textile structures are covered with an undefined shape of the reinforcing textile, the mechanical component properties may deteriorate. The patterns should be developed directly on the object to
apply the reinforcing structures to the desired 3D shape according to the Clothes and required load and thus avoiding rework. technical textiles Three-dimensional CAD programs are mainly applied to design complex components (AUTOCAD 2000, Pro Engineer, Thinkdesign 4.0, CATIA). The data obtained by the above programs may be transferred to the simulation program via suitable interfaces (IGES ± Initial Graphics Exchange Specification, 225 VDAFS ± interface suited for the exchange of free forms and curves). The textile preform should be in most exact accordance with the component geometry desired in the end (Figure 13). In particular for the realisation of freeform surfaces it is necessary to cut the fabric or multiaxial structures, so that it may be shaped later without irregular folds. After the patterns have been developed with regard to functional requirements using a three-dimensional model, surface generation and the development of the two-dimensional patterns are made feasible by an efficient software tool (Figure 14). Shearing in the pattern as well as material tension stresses and stretching may be analysed to provide the designer with information that enables him to produce suitable patterns of the reinforcing textile material. The material data obtained for the shearing, the material tension stress and also the stretching behaviour may be implemented in the simulation program by scanning the measurement curves and subsequent scaling or by loading a
Figure 13. 3D component
Figure 14. Conical shell ± shearing of a carbon fabric
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Figure 15. Spherical segment
file in the ASCII format. This investigation starts from an orthotropic structure for the majority of fabrics which have been tested so far. When high modulus carbon yarns are processed (E modulus > 650.00N/mm2), we may start from the fact that the potential deformation between the two-dimensional cutting and the multiple curved component surface results from the shearing deformation. After the computation has been completed, the shearing in the shaped patterns may be read. A comparison with the critical shearing angle, which indicates how far the share of threads can be twisted or compressed without folds, helps the designer to decide if the pattern is suited to the component surface. Another sample product is a spherical segment (Figure 15). Here you can see the developed pattern and you also get information about the behaviours. For the flattening process, a shear angle of approximately 40ë is necessary. Bibliography Brummund, J., Schenk, A. and Ulbricht, V. (1998), ``Beitrag zur Modellierung des Fallverhaltens in der Textilindustrie'', Proceedings GAMM, Bremen, Germany. Cusick, G.E. (1968), ``The measurement of fabric drape'', Journal of the Textile Institute, Vol. 59 No. 6, pp. 253-60. Fischer, P. (1997), ``Ermittlung der mechanischen KenngroÈûen textiler FlaÈchen zur Modellierung des Fallverhaltens unter BeruÈcksichtigung konstruktiver, faserstoffbedingter und technologischer AbhaÈngigkeiten'', Dissertation TU Dresden. Fischer, P., Krzywinski, S., RoÈdel, H., Schenk, A. and Ulbricht, V. (1999), ``Simulating the drape behavior of fabrics'', Textile Research Journal, Vol. 69 No. 5, pp. 331-4. Kirstein, T., Krzywinski, S. and RoÈdel, H. (1999), ``Ermittlung des Zusammenhanges zwischen Gestrickparametern, rechnergestuÈtzter Schnittgestaltung und Sicherung der Passform von Untertrikotagen zur QualitaÈtsverbesserung'', Vti aktuell, Vol. 3, p. 10. Krzywinski, S. (1999), ``Design und Materialverhalten ± Gestaltungseinheit zur Schnittentwicklung'', Mittex, Vol. 4, pp. 9-11. Krzywinski, S. (2000), ``Design und Materialverhalten'', Bekleidung und Wear, Vol. 3, pp. 12-17. Krzywinski, S., RoÈdel, H. and Schenk, A. (2000), ``Design und Materialverhalten ± Gestaltungseinheit zur Schnittentwicklung'', DWI Reports, pp. 182-9.
Krzywinski, S., Schenk, A., RoÈdel, H. and Fischer, P. (1999), ``Links between cloth design, pattern development and fabric behaviours: modern applied mathematics techniques in circuits, systems and control'', World Scientific and Engineering Society Press, pp. 396-400. Magloth, A. (1997), ``Design-Idee und Materialverhalten als Gestaltungseinheit'', Bekleidung & Wear, Vol. 20, pp. 13-14. RoÈdel, H., Ulbricht, V., Krzywinski, S., Schenk, A. and Fischer, P. (1997), ``Simulation of drape behaviour of fabrics'', Conference Proc. Advances in Fibre and Textile Science and Technologies, Mulhouse, France. RoÈdel, H., Ulbricht, V., Krzywinski, S., Schenk, A. and Fischer, P. (1998), ``Simulation of drape behaviour of fabrics'', International Journal of Science and Technology, Vol. 10 No. 3/4, p. 201. Schenk, A. (1996), ``Berechnung des Faltenwurfs textiler FlaÈchengebilde'', Dissertation, TU Dresden.
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Methods of automatic computerised cutting pattern construction Slavenka Petrak and Dubravko Rogale
Faculty of Textile Technology, Department of Clothing Technology, University of Zagreb, Zagreb, Croatia Keywords Clothing technology, Cutting, Pattern cutting Abstract The procedure of computerised automatic construction of a cutting pattern for men's shirt is presented. It is based on the calculation of construction measures necessary for the calculation of all the construction elements. The procedure of construction is similar to the conventional hand procedure, but is done using a computer, so that the locations of the coordinates of all the principal and auxiliary points on cutting part contours are calculated. Straight segments are drawn afterwards through these calculated points and curved segments interpolated.
International Journal of Clothing Science and Technology, Vol. 13 No. 3/4, 2001, pp. 228-239. # MCB University Press, 0955-6222
1. Introduction Construction preparation has been made significantly faster by introducing CAD/CAM systems for the job. However, the disadvantage of most computer systems used today in construction preparation is that the basic cutting pattern, which should be entered into the computer, must be constructed manually beforehand. Following the concept of intelligent manufacture and sale of garments, introduced by two leading researchers in the field, Stylios and Sotomi (1997) and Stylios et al. (1992), garment cutting pattern construction will be done using a computer, following individual body measurements. Researchers like Jo and Harlock (1990) have significantly contributed to solving the problem of computer construction and grading of cutting patterns, developing their own CAD systems for garment designing. On the basis of their results, Liu and Harlock have developed a system for automatic grading of cutting patterns, establishing a database with grading rules (1995a) and defining grading algorithms (1995b), to be used by a system of computerised cutting pattern grading (1995c). This paper presents the results obtained through development of one of the possible new methods of automatic computerised construction of cutting patterns (Petrak, 1999). The method has been developed after the example of computerised construction of a cutting pattern for men's shirt. A cutting pattern, being a plane figure, should be, if we want to enter it into a computer and store on the disk, transformed into a set of systematically organised digits, letters or special marks. From such an alphanumerical notation, the geometrical shape of the cutting pattern is reconstructed on the screen. In the investigation described here, the notation has been done using absolute rectangular co-ordinates of the points that define the location and
shape of straight and curved segments of cutting pattern segments. Investigation of the locations of auxiliary points on characteristic curves on the segments of cutting pattern contours is presented in the first part of the paper. Two methods are used ± conventional and interactive on a computer. The purpose of this is to define the manner of calculating the value of point coordinates. Experimentally determined locations of auxiliary points make it possible to define mathematical expressions for the calculation of the coordinates of these points, with the aim of precisely defining the shape of curved segments. Based on the results obtained and knowledge of the rules of construction, mathematical expressions are defined for the calculation of absolute rectangular co-ordinates of all the points needed for a computerised construction of men's shirt. The values for co-ordinates are obtained by calculation and substituted into the software AutoCAD R14, making possible automatic computerised construction of cutting patterns for men's shirt of the size given, or following individual body measurements. 2. Calculation of measurements necessary for the construction of men's shirt cutting pattern A part of the investigations into the development of the new method for automatic computerised construction of cutting patterns has been done by analysing and transforming conventional methods of garment construction, according to Knez (1990). It has been done by adapting the conventional methods to the computer, as well as by using the new software package, with a comprehensive theoretical basis. Table I shows the calculation of the measurements needed for conventional construction of cutting pattern for men's shirt from Figure 1. 3. Development of mathematical expressions and procedures for automatic computerised construction of cutting pattern for men's shirt After the expressions for calculating the co-ordinates of auxiliary points on characteristic curves of men's shirt cutting pattern have been determined, it is necessary to determine also the expressions for calculating absolute rectangular co-ordinates for all the points needed in automatic computerised construction of cutting patterns for men's shirt in the AutoCAD R14 program. It is necessary to obey the rules of construction for men's shirt, in the same way as when using the conventional method of construction. Since the basic aim of this investigation was to develop a method of automatic computerised construction of cutting patterns, the calculation is made so as to be able to give the co-ordinates of the points that define the segments of cutting pattern contours, without the need for auxiliary gridwork (unavoidable in conventional constructions). An exception is the constructions of sleeves and collars, where some auxiliary lines are drawn, with the aim of simplifying the calculation of particular points on the contours of cutting patterns for sleeves and collars. After the construction has been completed, auxiliary lines can be easily deleted,
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Table I. Calculation of the measures necessary for the construction of cutting patterns for men's shirt
Garment size: 40 Main Tv Og Os Ob Ov
body measurements: Height Chest circumference Waist circumference Hip circumference Neck circumference
= 174cm ) = 100cm = 94cm = 108cm = 40cm
Body SÏlt SÏot SÏgt
measurements calculated: Body back width Body armhole width Body chest width
= 19.86cm = 1/5.14Og + 0.5 = 11.11cm = 1/9Og = 19.06cm = 1/5.14Og ± 0.5
These measurements are taken from the standards for garment sizes, or are individual body measurements when the made-to-measure principle is used
Construction measurements calculated: SÏv Neckline width Do Armhole depth Dl Back length SÏl Back width SÏo Armhole width SÏg Chest width Vp Front height
= 6.67cm = 26.13cm = 46.50cm = 23.56cm = 15.61cm = 20.86cm = 26.13cm
= = = = = = =
Additional measurements: Dk Shirt length Dr Sleeve length Dor Cuff length
= 80.00cm = 62.25cm = 27.00cm
= 1/2Tv ± 7cm = 3/8Tv ± 7cm = (1/8Og + 1cm) 6 2
1/6Ov 1/8Og + 1/4 Dl + 2cm 1/4Tv + 3cm SÏlt + 4.5cm SÏot + 4.5cm SÏgt + 1cm Do
if no modification of cutting patterns is necessary. If modifications should be done, these lines can help in the process. The procedure of obtaining mathematical expressions used for calculating absolute rectangular co-ordinates of the points that define the segments of the bodice contour and back part of a men's shirt will be presented in the following chapter. The contour of the bodice is divided into six segments, marked by A, B, . . . , F, defined by six principal points that determine the beginning and the end of each segment (Figure 2), which can be clearly seen in the Figure. Then there are two principal points on the curved segments (OC and OF), as well as three auxiliary points on the curved segment of the back part of the neckline (OB1, OB2 and OB3). Employing the rules of conventional construction of cutting patterns for men's shirt, the expressions for calculating co-ordinates of all the principal points, except the points OD, OE and OF, are defined. The co-ordinates of these points are calculated using the data on the angles read from the cutting pattern for men's shirt constructed conventionally. Figures 3, 4 and 5 show enlarged parts of the bodice from which the angles are read to be used in calculating xeksp and yeksp. These values are further substituted into the expressions for calculating the co-ordinates of the points in question. The
Computerised cutting pattern
231
Figure 1. Construction of cutting pattern for classical men's shirt
Figure 2. Bodice contour
Figure 3. Values of the angles necessary for calculating the co-ordinates of the point OD
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232 Figure 4. Values of the angles necessary for calculating the co-ordinates of the point OE
Figure 5. Values of the angles necessary for calculating the co-ordinates of the point OF
expressions for calculating the co-ordinates of the auxiliary points (OB1, OB2 and OB3) are obtained much like the expressions for calculating the coordinates of auxiliary points on the curve of the back part of the armhole. Mathematical expressions necessary to calculate the co-ordinates of the main and auxiliary points on the bodice contour are grouped into a system for defining absolute Cartesian co-ordinates, made up from Equations (1) to (26). The point on the back side, in which the bodice is linked to the back of the shirt, is selected as the starting-point for the construction of the bodice of men's shirt. The point is designated with OA (Figure 2):
xOB1 xOB
xOB xOA
1
yOB yOA 5
2
yOB1 yOB
xOB yOC
xOC 0:22 yOB 0:035
3
4
xOB2 xOB yOB2 yOB xOB3 xOB yOB3 yOB
xOC 0:50 yOB 0:16 xOC 0:80 yOB 0:48
xOB yOC xOB yOC
v S
xOC xOB
xeksp
yeksp xeksp tg 5:54 xOD xOC
8
10
11
12
xeksp
13
yOD yOB yeksp
14
37 59 v 0:5 1=3 S xeksp 2:25 tg xeksp: yeksp 1:35 tg
15
xOE xOB
l S
xeksp
yOE yOB yeksp xeksp 1:5 sin 77 1:46 yeksp 1:5 cos 77 0:34 l xeksp xOF xOB S v 0:5 yOB 1=3 S yeksp xOG xOA
l S
16
17
18
77
yOF
7
72
v 1=3 S 1:80 tg
1
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6
9
v yOC yOB 1=3 S 51
5
19
20
21
22
23
yOG yOA 0:75
24
xOH xOG 11
25
yOH yOA
26
233
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Figure 6. Shirt bodice and back part contour
A similar procedure is used to obtain the equations for calculating absolute rectangular co-ordinates of all the points that define the contour segments of the back of the shirt. The contour of the back is divided into six segments, designated G, H, I, J, K and L (Figure 6). Each segment is defined by the starting and end principal point, while the segment G is additionally defined by two principal points on the segment: SI and SJ. These points are determined so that through them auxiliary lines on the depth of the armhole, as well as on the back length, are drawn additionally on the cutting patterns constructed, if the cutting pattern in question should be re-modelled (e.g. shirt model with accentuated waist). The same reason applies to the principal point SM on the segment I. The group of expressions for these purposes contains Equations (27) to (50).
The point OA is again taken as a starting-point: xSI xOA
27
ySI yOB
Do
28
xSJ xOA ySJ yOB
29 Dl
30
xSK xOA ySK yOB xSL xSK
xSN 1 xSN
l S
31 Dk
o 1 1=2 S
33
34
xSM xSL
35
ySM ySJ
36
xSN xSM
37
ySN ySI h i o 1 0:29 1=2 S
ySN 1 ySN
Do 5 0:012 h i o 1 0:55 xSN 2 xSN 1=2 S ySN 2 ySN
Do 5 0:053 h i o 1 0:74 xSN 3 xSN 1=2 S 5 0:13 l S
xSO xOA
xSO1
32
ySL ySK
ySN 3 ySN
Do
1
ySO ySN 1=20Og h i o 1 1:00 xSN 1=2 S
ySO1 ySN
Do ySP ySB
5 0:58 l S
xSP xOA 5
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38
39
40
41
42
43
44
45
46
47
48
1
49
0:75
50
235
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4. Making a calculation for the co-ordinates of the points on the contours of men's shirt cutting pattern Mathematical expressions obtained made it possible, in the next step, to make a calculation of absolute rectangular co-ordinates of all the points on the segments of men's shirt cutting pattern contours, as seen in Figure 7. The calculation is done in Excel 7.0, and it can yield the values of the co-ordinates for all the points necessary in computerised construction of cutting pattern for classic men's shirt, for any garment size, or made to measure. It is enough to enter the values for the main body measurements into the calculation, and the programs automatically calculate the construction measurements. Using these measurements and the mathematical equations above, simultaneous calculation is done for absolute rectangular co-ordinates for the points defining the segments of cutting pattern contours, Besides, in the final part of the calculation, the values of the co-ordinate points are grouped, as a part of the preparation for computerised construction of straight and curved segments of cutting pattern contours. To enter the values grouped in this way to AutoCAD, it is necessary to create a script data file. A script data file is a textual data file necessary to move the data from Excel into AutoCAD. Two script data files have been created for computerised construction of men's shirt cutting pattern in size 40. The first script data file contains the values of point co-ordinates for the construction of bodice, front and back part of the shirt. After entering the contents of this data file into AutoCAD, cutting patterns are constructed by chain linking of the segments of cutting part contours in a sequence, as defined by the script data file. The perimeter of the armhole is measured using functional commands from AutoCAD on the bodice, front and back part constructed in the above way, and this data are entered into the calculation. The values obtained by the calculation grouped for the purpose of constructing straight and curved sleeve and cuff segments, as well as the values obtained for the construction of the collar, are stored in the other script data file. Entering these data into AutoCAD, cutting patterns for sleeves, cuffs and collars are constructed. 5. Computerised drawing of cutting patterns The procedure of chain-linking the segments of men's shirt cutting pattern contours creates the basis for automatic computerised construction of classical men's shirt, with all the cutting patterns necessary. Cutting pattern construction is done in AutoCAD R14, entering the values of absolute rectangular co-ordinates for all the points defining the straight and curved cutting pattern segments, using the script data files described above. If necessary, cutting patterns can be modified, and later printed on a reduced scale using a laser printer, or be drawn using a plotter in the original size. Figure 8 shows all the cutting patterns for men's shirt in size 40, printed by a laser printer. It is also possible to construct a network of cutting patterns, as shown in Figure 9, with the aim of defining variable data for grading. The method of
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237
Figure 7. New method of automatic computerised construction of cutting patterns
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Figure 8. Cutting pattern for a classical men's shirt in size 40, constructed using the method of automatic computerised construction
Figure 9. Network of cutting patterns for men's shirt as a part of the preparation for defining variable data for grading
matrix transformations can be used for this purpose, the method of collective matrix transformation, the method of vector modules or the method of vector translations. 6. Conclusion It is obvious, from the presentation of a gradual development of the method of automatic computerised construction of cutting patterns, in the case of men's shirt, that the method developed is extremely precise and highly efficient. Of particular importance is the fact that this method can be used for a completely automated construction of men's shirt cutting pattern made to measure. It is especially important in view of the fact that the trend in contemporary garment manufacture is to produce, on an industrial basis, unique items of clothing, i.e. garments made to measure for the customer. As the method presented here has been developed exclusively for computerised construction of men's shirt cutting pattern, further investigation, rationalisation in some segments, and possible improvements could certainly result in a method appropriate for a much wider purpose, i.e. calculations could be made to allow computerised construction of cutting patterns for some other items of clothing. Such a method could most appropriately be used for men's outerwear, e.g. men's suits (where changes in cutting pattern are relatively minor from style to style), as well as for men's jackets (where the changes
concern design of the front part and variations in length). Further development of the method into the area of men's jacket would make possible cutting part construction to individual measurements, which means better fit to individual physical characteristics of the customers. References Jo, J.S. and Harlock, S.C. (1990), ``Developing an educational CAD system for garment design using CADDS 4X'', International Journal of Clothing Science and Technology, Vol. 2 No. 2, pp. 23-30. Knez, B. (1990), ``Konstrukcijska priprema u odjevnoj industriji'', UdzÏbenik SveucÏilisÏta u Zagrebu, Savez inzÏenjera i tehnicÏara tekstilaca Hrvatske, Zagreb. Liu, Z. and Harlock, S.C. (1995a), ``A computer-aided grading system for both block and adapted clothing patterns. Part I: Establishing the grade rule data file'', Textile Research Journal, Vol. 65 No. 1, pp. 10-13. Liu, Z. and Harlock, S.C. (1995b), ``A computer-aided grading system for both block and adapted clothing patterns. Part II: The grading algorithms'', Textile Research Journal, Vol. 65 No. 2, pp. 95-100. Liu, Z. and Harlock, S.C. (1995c), ``A computer-aided grading system for both block and adapted clothing patterns. Part III: The autograder system'', Textile Research Journal, Vol. 65 No. 3, pp. 157-62. Petrak, S. (1999), ``Methods of automatic computerised cutting pattern construction'', MSc thesis, University of Zagreb, Zagreb, Croatia. Stylios, G.K. and Sotomi, J.O. (1997), ``The integration of textile and apparel industries by networking of technical and trade data: the CyberTex network'', The 78th World Conference of The Textile Institute in Association with The 5th Textile Symposium of SEVE and SEPVE, Textiles and the Information Society, Vol. 3, Thessaloniki, Greece, pp. 77-86. Stylios G.K. et al. (1992), ``A new concept in garment manufacture'', International Journal of Clothing Science and Technology, Vol. 4 No. 5, pp. 45-8.
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The current issue and full text archive of this journal is available at http://www.emerald-library.com/ft
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240
Study of the tensile force of thread in relation to its pre-tension Darja ZÏunicÏ-Lojen and Jelka GersÏak
Faculty of Mechanical Engineering, Institute for Textile and Garment Manufacture Processes, University of Maribor, Maribor, Slovenia Keywords Sewing, Stitch, Threads Abstract The perfect interlacing of needle and bobbin thread in the stitch formation process and seam appearance depends first of all on correct pre-tension of the tension regulator. Changes in the pre-tension settings also have a direct influence on the tensile force during the sewing process. This contribution presents the influence of pre-tension in a defined area on the tensile force in important phases of the stitch formation process. In addition the influence of the stitch velocity on tensile force was investigated. On the basis of statistic analysis it was ascertained in which pretension area and stitch velocity the significant differences between tensile forces occurred.
1. Introduction The need to predetermine sewing-machine settings and their reproducibility is increasing. Therefore it is necessary to know the optimal sewing parameters for applied material and the relationship between quality of seam, sewing velocity, sewing thread tensile force and the pressure force of the presser foot. On the other hand, mechanical-technical solutions are also needed, which will enable automatic settings of the appropriate parameters during the sewing process. 2. Tensile force in the sewing thread The thread unrolls from the thread holder and slides over the guides and stretch elements into the tension regulator, where static pre-tension acts on the thread, which is important for regular interlacing of both threads in the middle of the material. Then the thread slides over the thread spring, guides, take-up lever eye to the guide on the needle bar, along the long groove of the needle, through the needle eye until the last stitch is made. Because of this characteristic sewing thread movement in combination with the functional dependent movement of the take-up lever, sewing needle, bobbin case and also fabric transport, the thread is exposed to different tensile loadings. These loadings change depending on the main shaft position. The characteristic tensile loadings of the sewing thread, depending on the main shaft position, can be seen as peaks of tensile force in Table I (Ferreira et al., 1994). International Journal of Clothing Science and Technology, Vol. 13 No. 3/4, 2001, pp. 240-250. # MCB University Press, 0955-6222
2.1 Static pre-tension of the sewing thread The correct interlacing of threads depends largely on the correct pre-tension of the tension regulator. The pre-tension on the tension regulator is set by hand
using the spring, which presses on the plates system, between which the sewing thread slides. Considering the balance condition (Figure 1): FN
1 x2 FPR 0 x1 2 2 2
FN FPR FPO 2
2
Tensile force of thread
241
the pressing force, with which the tension regulator acts on the moving thread leg, is expressed by (GersÏak, 1990): FN x2 FPO ;
3 2 2
x1 x2 where: FN ± pressure force which acts on the thread over the plates of tension regulator, in cN; FPO ± pressure force which acts over the spring, in cN; FPR ± pressure force between the plates of the tension regulator, in cN; x1 ± distance between the centre of tension regulator and point, where the plates press the sewing thread, in mm; and x2 ± distance between the centre of tension regulator and point, where the plates are in contact, in mm. In the tension regulator area the friction force also acts on the thread as well as the pressure force. The tensile force needed to pull the thread over the tension regulator is given by (GersÏak, 1990): FN FN 0 R e4 4 m4 a R
4 FVR FV4 2 2 where: F'V4 ± tensile force acting on thread leg before the tension regulator, in cN; Peak 1
Main shaft angle 0ë > j < 95ë
2 3
105ë > j < 150ë 280ë > j < 325ë
4
325ë > j < 355ë
Characteristic positions of the particular sewing-machine elements The thread take-up lever completes its upward movement, drawing slack needle thread through the fabric and pulling the bobbin thread off the bobbin and setting the stitch Needle eye penetrates the fabric Multipeak effect owing to the movement upwards of the needle and tightening of the needle thread loop around the bobbin case The bobbin thread is pulled off the bobbin by the needle thread loop on its way upwards
Table I. The important peaks of the tensile force
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242
Figure 1. Tension regulator
F'V5 ± force, acting on the thread before axle of the tension regulator, in cN; FV5 ± tensile force in the area of axle of the tension regulator, in cN; FVR ± common tensile force as a result of tension regulator effect on moving thread leg, in cN; mR ± friction coefficient between the tension regulator plates; m4 ± friction coefficient on the tension regulator axle; and a4 ± angle about where the thread embraces the tension regulator axle, in rad. On the basis of Equation (4) it can be seen that the thread tensile force directly depends on the pressure force on the tension regulator. Despite this fact, present technical solutions for the tension regulator on industrial sewingmachines do not enable setting of pre-tension with the possibility of reading the settings of force values, which could later enable reproducibility of the setting. What is desirable is the possibility of regulating pre-tension regarding the necessary thread length in the stitch formation process. For assessment of pretension some instruments can be used, but this is not a good solution for
production. Some researchers have studied these problems and found some solutions, like changing the system of an ``old'' tension regulator with a pneumatic cylinder (KoÈhler and Zipplies, 1998), or a system that enables automatic setting of sewing parameters during sewing (Stylios and Sotomi, 1995). The proper setting of thread pre-tension on the tension regulator is first of all determined on the basis of the seam optic and subjective evaluation of the seam quality. But this gives no assurance that the lowest pre-tension is achieved. The forces acting on the sewing thread during sewing have an influence on reduction of thread strength, so the lowest value of pre-tension should be chosen. The highest tensile force in the thread occurs usually at the moment when the take-up lever is in the upper position and pulls the amount of thread needed to form the next stitch. The thread length, which the take-up lever pulls over the tension regulator, and position of the interlacing of both threads in the material depend on the static pre-tension setting on the regulator. 3. Methodology The influence of static pre-tension on the tensile force was investigated. For this purpose the measurements of the thread tensile force were done using the sewing-machine Brother Exedra DB2-737, at the following stitch velocities: 2,000rpm, 3,000rpm and 4,000rpm, at static pre-tension from 2.2N to 3.2N, with a step 0.2N. These ``static forces'' were measured with the instrument, Coats tensile meter. A needle with metric number 70Nm was used. The analyses were done with the core PES thread, with linear density 12.5 6 2tex. The 100 per cent wool fabric in plain weave and weight 157gm±2 was used. At each ``static'' pre-tension setting and stitch velocity the tensile forces were measured. Also the peaks gained at three positions of the main shaft angle, respectively peaks 1, 3 and 4, were read. 4. Results The results of the measurement of tensile force, respectively particular peaks regarding pre-tension at stitch velocities n1 = 2,000rpm, n2 = 3,000 rpm and n3 = 4,000 rpm are given in Table II. The tensile forces regarding the main shaft turn for stitch velocity 2,000rpm are given in Figure 2. 4.1 Influence of the pre-tension on the tensile force Tables III to V give the results of the statistical analysis, based on F and t tests. Using these tests it was investigated whether among the mean values of the tensile force these occur statistically significant differences regarding pretension (with 99 per cent or 95 per cent level of confidence). From diagrams of tensile force peaks-pre-tension it can be seen that polynomial of the fourth degree describes the curves very well (Figure 3). y ax4 bx3 cx2 dx e
5
Tensile force of thread
243
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244
Table II. The tensile force peaks regarding the pretension with calculated standard deviation and variation coefficient
Static pretension Fst/N 2.2 2.4 2.6 2.8 3.0 3.2 2.2 2.4 2.6 2.8 3.0 3.2 2.2 2.4 2.6 2.8 3.0 3.2
Stitch velocity n/rpm 2,000
3,000
4,000
F/N
Peak 1 s/N CV/%
Tensile force/N Peak 3 F/N s/N CV/%
F/N
Peak 4 s/N CV/%
1.324 1.348 1.551 1.736 1.734 1.719 1.537 1.461 1.626 1.690 1.694 1.779 1.665 1.615 1.749 1.902 1.866 1.890
0.034 0.045 0.053 0.059 0.086 0.065 0.1001 0.033 0.053 0.059 0.045 0.030 0.063 0.070 0.064 0.068 0.081 0.066
0.676 0.710 0.715 1.216 1.081 1.284 0.949 0.779 0.823 0.881 0.892 0.877 0.855 0.919 0.935 1.025 1.068 1.015
1.115 1.147 1.216 1.410 1.509 1.518 1.115 1.093 1.175 1.243 1.276 1.379 1.069 1.070 1.199 1.271 1.270 1.289
0.043 3.874 0.049 4.246 0.070 5.725 0.090 6.359 0.057 3.792 0.070 4.584 0.132 11.876 0.109 9.966 0.054 4.618 0.084 6.750 0.046 3.637 0.060 4.318 0.068 6.344 0.063 5.907 0.050 4.157 0.055 4.296 0.065 5.127 0.052 4.066
2.599 3.310 3.400 3.425 4.950 3.784 6.530 2.289 3.279 3.495 2.660 1.686 3.790 4.308 3.661 3.573 4.315 3.508
0.053 0.043 0.086 0.311 0.194 0.329 0.283 0.042 0.045 0.069 0.041 0.056 0.039 0.052 0.056 0.073 0.103 0.054
7.780 5.995 12.055 25.576 17.979 25.622 29.771 5.403 5.467 7.878 4.642 6.328 4.553 5.659 5.951 7.119 9.607 5.338
Figure 2. The tensile force ± main shaft turn at n2 = 2,000 rpm and Fst = 2.6N
4.2 The influence of the stitch velocity on tensile force Furthermore, from the results of the statistical analysis it was evaluated whether the mean values of tensile force significantly differentiate regarding the stitch velocity (Table VI). The alteration of particular peaks of the tensile force regarding the stitch velocity of the sewing-machine is shown in Figures 4 to 6: y1 6:8355x41 2
R 0:99
74:857x31 305:66x21
551:19x1 371:73
6
y3 2:9154x43
31:757x33 129:11x23
231:87x3 156:2
21:531x34 91:414x24
171:11x4 119:91
7
R2 1 y4 1:8882x44
8
R2 0:99 Peak Peak 1 Peak 3 Peak 4
Peak
2.2N ± 2.4N t H(0),a=0.05 t H(0),a=0.01 t H(0),a=0.05
2.2N ± 2.4N
Peak 1 t H(0),a=0.01 Peak 3 t H(0),a=0.01 Peak 4 t H(0),a=0.01
Peak
2.370 rejected 2.741 rejected 2.696 rejected
7.404 rejected 1.860 not rejected 0.707 not rejected
2.2N ± 2.4N
Peak 1 t H(0),a=0.01 Peak 3 t H(0),a=0.01
2.869 rejected 5.282 rejected
2.4N ± 2.6N t H(0),a=0.01 t H(0),a=0.01 t H(0),a=0.01
2.6N ± 2.8N
16.057 rejected 0.313 not rejected 4.422 rejected
2.4N ± 2.6N t H(0),a=0.01 t H(0),a=0.01 t H(0),a=0.01
14.300 rejected 3.934 rejected 3.732 rejected
2.4N ± 2.6N t H(0),a=0.01 t H(0),a=0.01
Peak 4 t 0.054 t H(0),a=0.01 not rejected H(0),a=0.01
7.594 rejected 1.093 not rejected 8.565 rejected
t H(0),a=0.01 t H(0),a=0.01 t H(0),a=0.01
12.815 rejected 8.493 rejected 9.342 rejected
2.6N ± 2.8N t H(0),a=0.01 t H(0),a=0.01 t H(0),a=0.01
4.469 rejected 3.841 rejected 3.688 rejected
2.6N ± 2.8N t H(0),a=0.01 t H(0),a=0.01
8.810 rejected 5.263 rejected
2.8N ± 3.0N t H((0),a=0.01 t H(0),a=0.05 t H(0),a=0.01
0.119 not rejected 2.010 rejected 5.125 rejected
2.8N ± 3.0N t H(0),a=0.01 t H(0),a=0.01 t H(0),a=0.01
0.258 not rejected 0.696 not rejected 1.903 not rejected
2.8N ± 3.0N t H(0),a=0.01 t H(0),a=0.01
1.863 not rejected 1.850 not rejected
3.0N ± 3.2N t H((0),a=0.01 t H(0),a=0.01 t H(0),a=0.01
0.784 not rejected 2.912 rejected 0.525 not rejected
3.0N ± 3.2N t H(0),a=0.01 t H(0),a=0.01 t H(0),a=0.01
8.594 rejected 1.123 not rejected 7.443 rejected
Tensile force of thread
245 Table III. Statistical analysis of the significant differences of the mean values of the tensile force regarding the pre-tension at n1 = 2,000rpm
Table IV. Statistical analysis of the significant differences of the mean values of the tensile force regarding the pre-tension at n2 = 3,000rpm
3.0N ± 3.2N t H(0),a=0.05 t H(0),a=0.05
1.262 not rejected 2.447 rejected
t 5.226 t 0.011 t 1.171 H(0),a=0.01 rejected H(0),a=0.01 not rejected H(0),a=0.01 not rejected
Notes: If null hypothesis H(0): m1 = m2 is rejected, the differences between mean values are significant
Table V. Statistical analysis of the significant differences of the mean values of the tensile force regarding the pre-tension at n3 = 4,000rpm
Figure 3. The tensile force peak values regarding the pre-tension at n3 = 3,000rpm
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Static pre-tension Fst/N 2.2 2.4
246
2.6 2.8 3.0 3.2 3
2.2 2.4 2.6 2.8 3.0 3.2
4
2.2 2.4
Table VI. Statistical analysis of the significant differences of the mean values of particular tensile force peaks regarding the stitch velocity
2.6 2.8 3.0 3.2
Comparison of the stitch velocity n/rpm
t value
2,000-3,000 3,000-4,000 2000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000 2,000-3,000 3,000-4,000
11.011 5.743 11.118 14.191 5.480 7.945 3.005 12.561 2.273 9.980 4.597 8.206 3.937 0.296 6.344 11.214 6.087 8.345 5.747 7.599 5.222 8.560 6.678 9.476 2.717 0.981 2.518 7.614 2.516 1.698 62.892 1.484 17.326 0.372 8.322 6.047
t test
H(0),a=0,01 Rejected Rejected Rejected Rejected Rejected Rejected Rejected Rejected Rejected Rejected Rejected Rejected Rejected Not rejected Rejected Rejected Rejected Rejected Rejected Rejected Rejected Rejected Rejected Rejected Rejected Not rejected Rejected Rejected Rejected Not rejected Rejected Not rejected Rejected Not rejected Rejected Rejected
5. Discussion On the basis of the achieved results of measurement and processing of statistical data, the tensile force in the thread regarding the settings of the pre-tension on the tension regulator and the stitch velocity was investigated. The analyses of seam appearance showed that optimal appearance was achieved at the static force 2.6N. This was the lowest value of the pre-tension at which the seam corresponds with quality requirements. The interlacing of threads was also suitable at settings 2.8N to 3.2N. At lower settings (2.2N and
2.4N) the interlacing was unsuitable, since it appeared on the bottom side of the fabric.
Tensile force of thread
5.1 Analysis of the influence of pre-tension force on the tensile force Based on the statistical analysis of the mean values of the tensile force at the stitch velocity 2,000rpm (Table III), it was found that static pre-tension influences the tensile force:
247
.
.
.
At Peak 1 it was confirmed that a significant difference between settings 2.2N to 2.8N appeared, while insignificant differences were seen at settings 2.8N to 3.2N. At peak 3 no significant differences at static pre-tension between 2.4N and 2.6N were seen. At peak 4 there were no significant differences at settings of the static pre-tension between 3.0N and 3.2N.
With the comparison of the mean values of the tensile force at stitch velocity 3,000 rpm (Table IV), it was found: .
.
.
At peak 1 no significant differences were found between static pretension 2.8N and 3.0N. At peak 3 no significant differences were found between static pretension 2.2N in 2.4N, 2.8N and 3.0N and between 3.0N and 3.2N. At peak 4 no significant differences were found between static pretension 2.2 N and 2.4N, as well as between 2.8N and 3.0N.
With the statistical analysis of significant differences between the mean values of the tensile force at stitch velocity 4,000rpm (Table V), it can be stated that: .
.
At peak 1 there were no significant differences between the static pretension 2.8N and 3.0N and between 3.0N and 3.2N. At peak 3 no significant differences were found at static pre-tension between 2.4N and 2.6N and between 2.8N and 3.0N.
Figure 4. Tensile force regarding stitch velocity ± Peak 1
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Figure 6. Tensile force regarding stitch velocity ± Peak 4
.
At peak 4 no significant differences were found at static pretension between 2.2N and 2.4N, 2.8N and 3.0N and between 3.0N and 3.2N.
From diagrams of the tensile forces in the thread regarding pre-tension forces it can be seen that values of the tensile force increase with increasing pre-tension. Only values at lowest static pre-tension do not follow this trend. At this value the tensile forces are mostly higher, as at the next higher setting of the pretension. At higher settings of static pre-tension the values of the tensile force can also decrease, but the differences are mostly insignificant (Table II). The greatest changes in the tensile force were seen at settings of pre-tension between 2.6N and 2.8N, (Figure 3). The increase was most intensive at peak 1 followed by peak 3, while at peak 4 the increase was smaller. The tensile force regarding the pre-tension could be described with the polynomial of fourth degree.
5.2 Analysis of the influence of the stitch velocity on the tensile force Also an investigation of the influence of stitch velocity on three tensile force peaks was carried out (Table VI). Between values of peak 1, a significant difference can be seen at all settings of pre-tension regarding the stitch velocity. At peak 3 significant differences appeared between forces at all analysed velocities, except at static pre-tension 2.2N, while at peak 4 significant differences between stitch velocities 2,000 and 3,000rpm were stated. In diagrams tensile force ± stitch velocity (Figures 4 to 6), it can be seen: .
.
.
With the increase of stitch velocity the values of peak 1 of the tensile force increase at most pre-tension settings. For peak 3 it is evident that at lower static forces (from 2.2N to 2.6N) the tensile force values increase slightly when the stitch velocity is increasing. At higher static forces the values at n2 = 3,000 rpm are lower when compared to n1 = 2,000 rpm, while at n3 = 4,000 rpm they rise again. At peak 4 the opposite tendency is seen; with the increase of stitch velocity the tensile force values decrease. At higher static forces (2.8N to 3.2N) this decrease is more obvious than at lower values. At almost all settings of the pre-tension the lowest value of the tensile force is achieved at velocity 3,000 rpm. At n3 = 4,000 rpm values increase slightly, but there are no significant differences between the tensile force values at these two velocities.
6. Conclusions The results of the research showed that with increase of the static pre-tension the peak values of the tensile force also increased. However, in the range of the static pre-tension, where the interlacing was regular, no significant differences appeared between the majority of tensile forces regarding static pre-tension 2.8N to 3.2N at stitch velocities 3,000 and 4,000 rpm. The differences between peaks 1, 3 and 4 are shown as the tensile force changes; at peak 1 the step between particular values is much higher than at peaks 3 or 4. The polynomial of the fourth degree clearly describes the course of tensile force peaks regarding the pre-tension. The stitch velocity also influences the tensile force value. The stitch velocity alteration significantly affects the tensile force at peak 1 in all settings, at peak 3 with some exceptions, while at peak 4 no significant differences at almost all values of the tensile force regarding velocities 3,000 and 4,000 rpm were observed. With the increase of stitch velocity the values of peak 1 increase, the values of peak 3 usually increase, while at peak 4 they decrease slightly.
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References Ferreira, F.B.N., Harlock, S.C. and Grosberg, P. (1994), ``A study of thread tension on a lockstitch sewing-machine (Part I)'', International Journal of Clothing Science and Technology, Vol. 6 No. 1, pp. 14-19. GersÏak, J. (1990), ``The influence of sewing needle temperature and type of sewing thread on seam tenacity'', Doctoral thesis, Zagreb (in Croatian). KoÈhler, E. and Zipplies, E. (1998), ``Reproducible sewing parameters'', DNZ, No. 5, pp. 46-9 (in German). Stylios, G. and Sotomi, J.O. (1995), ``A neuro-fuzzy control system for the intelligent overlock sewing machine'', International Journal of Clothing Science and Technology, Vol. 7 No. 2/3, pp. 49-55.
The current issue and full text archive of this journal is available at http://www.emerald-library.com/ft
Impact of The impact of auxiliary auxiliary devices devices on sewing-machines upon processing parameters of 251 sewing operations
Dubravko Rogale, Zvonko DragcÏevic and Anica Hursa
Faculty of Textile Technology, Department of Clothing Technology, University of Zagreb, Zagreb, Croatia Keywords Garment, Technology, Sewing, Sewing-machines Abstract An investigation is presented of the impact of mechanical auxiliary devices on sewingmachines upon the processing parameters of sewing operations. Processing parameters are investigated at an ergonomically designed workplace, on a modern sewing-machine, equipped with a processing microcomputer. Measuring samples are 300 to 1,000mm long, and stitching speeds are pre-programmed ± 1,500 to 4,700rpm. Values for sewing operation processing parameters are measured and stored using the measuring system for processing parameters MMPP, developed especially for the purpose of research in the field of garment engineering. The results obtained indicate that using a tape piper the basic time needed to perform the sewing operation is reduced by up to 61.2 per cent, while the use of a hemmer reduces it by 38.3 per cent. Specific time for sewing 1m of seam is reduced using the above auxiliary devices as follows: by 64.5 per cent using a tape piper and by 41.8 per cent using a hemmer. The degree of sewing-machine utilisation is increased by 110.6 per cent using a tape piper, and by 59.8 per cent using a hemmer. Average stitching in machine-hand sub-operations is increased with a tape piper from 1,041 to 3,914rpm, and from 1,176 to 3,959rpm with a hemmer. The operation structure is altered by using auxiliary devices, achieving rationalisation of the movements constituting auxiliary-hand sub-operations, which has a considerable impact on the processing parameters involved.
1. Introduction All sewing operations are characterised by the relatively short duration, the high degree of repetitiveness and the high psychophysical engagement of the worker in performing them. These are the main reasons why the work on production lines is considered to be hard and exhausting. In contemporary garment manufacturing processes, special attention is paid to the structure and time needed to perform the operations involved. Increased savings in time are required, as they define productivity, productive capacity and, finally, the price of an article of clothing. Auxiliary devices (attachments) on sewing-machines are used to make the construction of various types of seams easier and faster. The contribution of these devices in garment sewing is assessed on the basis of previous experience, and it is generally accepted that they reduce the time interval needed to perform an operation, raise the quality of the seam produced and reduce fatigue on the part of the worker. Processing parameters of garment sewing operations are characteristic technological values, appearing in the course of performing garment-sewing operations. Based on the characteristics of particular sewing operations,
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processing parameters can be divided into three groups ± with time needed to perform the operation, sewing-machine stitching speed, and the length of the contour of the part of the seam connected as a three factors used to group them. Measuring, calculating and defining processing parameter values is done using numerical and statistic methods, according to pre-defined mathematical expressions (Rogale, 1995; Rogale et al., 1997). 2. Measuring system, samples and conditions of measuring Measurements were performed on the system for measuring processing parameters, MMPP, developed specifically for the purpose of researching processing parameters of garment sewing operations. Measuring and storing processing parameters is mostly based on interval measuring times and the respective rotation speed of the sewing-machine main shaft. Real and average sewing-machine speeds are thus defined, highest speed achieved, acceleration in sewing, number of stitches in a seam and the like. Infra-red (IC) reflexive measuring transformer is used to measure processing parameters, together with passive infra-red movement detector (PID), active microwave movement detector (AMD), measuring device, A/D transducer and a personal computer (PC). Two camcorders, for recording in two planes, equipped with video recorders, can be installed with the above measuring equipment (DragcÏevic et al., 1997, 1998, 1999; Rogale and DragcÏevic, 1997). The impact of using a tape piper and a hemmer on the values of sewing operation processing parameters was investigated in sewing straight seams of various lengths (300, 400, 500, 700 and 1,000mm), and at various stitching speeds (1,500, 2,500, 3,500 and 4,700rpm). The measurements were done at an ergonomically designed workplace, on a Brother sewing-machine, designated DB2-B755-403A ± Mark III, equipped with a processing microcomputer F-100. Knowing the physical and mechanical properties of the fabric sewn is essential for noticing in time some inadequacies in garment manufacturing processes (GersÏak and SÏaric, 1995). It is also an important factor in the dynamic modelling of fabric drape behaviour (Stylios et al., 1996). The fabric used for measuring samples was made of 100 per cent cotton, in twill weave K 21. Its surface mass was 260g/m2 (HRN F.S2.016). Warp density was 26 yarns/cm, and weft density 20 yarns/cm, with warp count of 63 tex, and weft of 30 tex. Breaking strength Fp [N] and breaking elongation e [per cent] were measured on a dynamometer with a constant rate of lower clamp, and pre-loading of 500g (DIN 53837). The distance between the dynamometer clamps was 200mm. Breaking strength and breaking elongation were measured warpwise and weftwise, and the following results were obtained: . warpwise breaking strength: 1,045.8N, weftwise: 338.5N, and . warpwise breaking elongation: 28.8 per cent, weftwise: 15.2 per cent. Warp thickness (HRN F.S2.021) was d100: 0.537mm (s: 0.013mm and CV: 2.44 per cent), and initial recovery angle (HRN F.S2.018) ao:50.96ë. The fabric was tested on a FAST system for objective evaluation of physical and mechanical properties of woven fabric, and the following results were obtained:
Impact of auxiliary devices
.
surface layer thickness: 0.142mm;
.
relaxed surface layer thickness: 0.164mm;
.
warpwise flexibility: 126.8mNm;
.
weftwise flexibility: 20.8mNm;
.
shear rigidity: 335Nm-1;
.
warpwise relaxation shrinkage: ± 4.1 per cent;
.
weftwise relaxation shrinkage: ± 0.8 per cent;
.
warpwise wet elongation: 0.4 per cent; and
.
weftwise wet elongation: 0.7 per cent.
253
Thickness (HRN F.S2.021) and initial recovery angle (HRN F.S2.018) for cotton tape used to make the hem were as follows: d100: 0.293mm (s: 0.006mm and CV: 2.19 per cent) and ao: 94.48ë (Hursa, 2000). 3. Results The results of the impact of tape piper and hemmer on processing parameters in garment sewing operations are given on the basis of the investigations performed. Table I gives the results of statistical data processing of basic duration times for the operation of piping and hemming the measuring sample, for various measuring sample lengths and at various sewing-machine stitching speeds. Sewing-machine Average basic time, to [s] stitching speed Sample Sample Without With tape Without vsi[rpm] designation length l [mm] tape piper piper hemmer 1,500
2,500
3,500
4,700
L1 L2 L3 L4 L5 L1 L2 L3 L4 L5 L1 L2 L3 L4 L5 L1 L2 L3 L4 L5
300 400 500 700 1,000 300 400 500 700 1,000 300 400 500 700 1,000 300 400 500 700 1000
18,745 21,088 23,222 34,100 44,045 16,190 17,204 19,812 28,658 37,514 14,843 16,459 18,056 24,189 35,681 13,469 14,634 16,707 19,597 33,828
12,522 14,809 16,905 18,845 23,201 8,985 10,122 11,638 12,999 15,818 7,020 7,844 9,195 10,772 13,845 5,805 7,048 8,407 9,938 13,118
11,664 15,743 19,110 22,093 28,932 10,276 14,025 17,175 20,581 26,723 9,639 12,502 14,482 19,008 23,844 9,087 11,266 13,492 17,499 22,887
With hemmer 10,420 13,864 15,903 17,660 24,806 9,039 11,980 13,424 15,035 18,767 8,097 9,993 10,937 13,360 15,584 7,073 8,299 9,373 10,802 14,420
Table I. Average basic time for the technological operations of piping and hemming the measuring samples, without attachment, and with it
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Figure 1. Flow of functional dependence of the operation average time on the measuring sample length, at sewing-machine stitching speeds of 1,500, 2,500, 3,500 and 4,700rpm
Figure 1 shows functional dependence of average time needed for piping a measuring sample selected, using a tape piper and without it, for all the sewingmachine stitching speeds available. Processing parameters such as the degree of sewing-machine utilisation, specific time for sewing 1m of seam and average stitching speed, as realised in the course of performing machine-hand suboperations. Figure 2 shows the degree of sewing-machine utilisation in performing a piping operation on a measuring sample without a tape piper, and Figure 3 the same operation with a tape piper used. Specific sewing speeds for the operation of piping without a tape piper can be seen in Figure 4, and the speeds when using a tape piper in Figure 5. Figure 6 shows average stitching speeds of hand-machine sub-operations for various measuring sample lengths in piping without a tape piper, and Figure 7 when a tape piper is used. Figure 8 shows a spatial diagram depicting dependence of basic times needed for the operation upon the pre-programmed stitching speeds and various measuring sample lengths, for the operation of piping without a tape piper, while the situation when a tape piper is used is depicted in Figure 9. Statistical data processing was performed in a similar way for the operation of hemming. Using the MTM system and analysis of the basic movements with adequate changes (movement length, accuracy and dynamics of performing, necessary visual concentration and muscular control) for both operations, it can be seen that the application of auxiliary devices (attachments) results in a simplified system of movements, as these devices make seam formation easier, while the worker is required only to position the workpiece and guide it in the course of sewing. Table II shows the analysis of sets of basic movements in the
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Figure 2. Sewing-machine utilisation in the operation of piping without a tape piper
Figure 3. Sewing-machine utilisation in the operation of piping with a tape piper
operation of piping without a tape piper, and Table III in the operation of hemming without a hemmer. 4. Discussion The results presented in this paper have been obtained by investigating the impact of tape piper on the processing parameters of sewing operations. Basic time necessary to pipe a measuring sample 300mm long (designated L1), without
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Figure 4. Specific sewing time for the operation of piping without a tape piper
Figure 5. Specific sewing time for the operation of piping with a tape piper
a tape piper, is 18.7s on average, at the sewing-machine stitching speed of 1,500rpm. When a tape piper is used at the same measuring sample length and at the same stitching speed, average basic time is 12.5s, which means reduction by 33.2 per cent, with compared with the operation without the attachment. Average basic time for a 300mm long sample, at the stitching speed of 4,700rpm for piping with a tape piper is 5.8s, which is a reduction of 57 per cent compared with the situation when no tape piper is used at the same stitching speed.
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Figure 6. Average stitching speeds for the operation of piping without a tape piper
Figure 7. Average stitching speeds for the operation of piping with a tape piper
Basic time for the operation is also reduced by increasing the stitching speed of the sewing-machine. Average basic time for the sample of 300mm, at the stitching speed of 4,700rpm is 13.5s, without a tape piper. Increasing the sewing-machine speed reduces the basic time for the operation by 27.8 per cent. Average basic time for the operation of piping a sample 1,000mm long without a tape piper, at the sewing-machine speed of 4,700rpm, is 33.8s, which is, compared with the machine speed of 1,500rpm, a reduction by 23.2 per cent. For
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Figure 8. Three-dimensional graph depicting the dependence of the basic time needed for the operation of piping without a tape piper upon the measuring sample length and sewing-machine stitching speed
Figure 9. Three-dimensional graph depicting the dependence of the basic time needed for the operation of piping with a tape piper upon the measuring sample length and sewingmachine stitching speed
the operation with a tape piper, this reduction of the average basic time is as Impact of much as 43.5 per cent. auxiliary devices The results of investigating the degree of sewing-machine utilisation, as seen in Figures 2 and 3, indicate that it is higher for the operations of piping with a tape piper attached. The results presented in Figure 2 say that the degree of sewing-machine utilisation rises with the increased sample length. 259 For the stitching speed of 1,500rpm and sample length of 300mm, the utilisation is 25.7 per cent, while for the sample of 1,000 mm it is 39.2 per cent, which means higher machine utilisation by 52.5 per cent. If machine utilisation degree is investigated related to the variations in machine stitching speed, it is obvious that the degree of machine utilisation is lowered with increase in speed, as the working time of the machine is shorter if it works at a higher speed. For various sample lengths, the degree of machine utilisation is reduced by 26.5 to 50.2 per cent, with the increase of stitching Set of movements No. Description of the sub-operation 1 2 3 4 5 6 7 8
Parallel positioning of the ribbon and measuring sample Initial tucking-in of the ribbon Positioning under the sewing foot Aligning the ribbon for sewing the first segment Positioning under the needle Sewing the first segment (13cm) Aligning the ribbon during the break in sewing Sewing the second segment (17cm)
Set of movements No. Description of the sub-operation 1 2 3 4 5 6 7
Tucking-in the measuring sample Additional tucking-in Positioning under the sewingmachine needle Sewing the first segment (15cm) Tucking-in the edge of the measuring sample for the second segment, during break in sewing Additional alignment Sewing the second segment (15cm)
Sequence of movements
Time TMU (s)
M4C/RL1/R4E G1B/M6C/P1SE/RL2 FM (M8C)/FM R10B/G5/M6C/P1SE/ R4E/ RL2 FM(M6C)/P1SE/FM machine time (tt)ar
9.7 (0.35) 14.9 (0.54) 17.0 (0.61) 20.9 (0.75) 22.6 (0.81)
R16B/G1B/M4C/R4E 20.0 (0.72) machine time (tt)ar S 105.1 (3.78)
Sequence of movements G1B/M6C/P1SE/RL1 R15B/G5/M15B/RL2
Table II. Analysis of the sets of basic movements in performing the operation of piping a measuring sample with a ribbon, without a tape piper, performed employing the MTM system
Time TMU (s) 16.9 (0.61) 18.0 (0.65)
FM (M6C)/P1SE/FM 22.6 (0.81) machine time (tt)ar R20B/G5/M6C/P1SE/R4E/ RL2 24.6 (0.89) R15B/G5/M15B/RL2 18.0 (0.65) machine time (tt)ar S 100.1 (3.61)
Table III. Analysis of the sets of basic movements in performing the operation of hemming a measuring sample, without a hemmer, performed employing the MTM system
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speed from 1,500 to 4,700rpm. As has already been said, the degree of sewingmachine utilisation is increased when a tape piper is used, the range of the increment being from 14.8 to 110.6 per cent. The results obtained from the investigations of the changes in specific sewing times, related to the operation in question, as depicted in Figures 4 and 5, indicate that these times are almost double for the operation without a tape piper (valid for all the sample lengths and machine stitching speeds). Increasing the stitching speed of the sewing-machine results in reduced specific time, for 35.8 per cent with the samples of 300mm, when the speed is increased from 1,500 rpm to 4,700rpm, and no tape piper is used. Under the same process parameter and the same sample length, the reduction is 21.1 per cent for the sample 1,000mm long. Specific time of sewing 1m of seam is reduced by 51.2 per cent, for the sample 300mm long, when the stitching speed is increased from 1,500 to 4,700rpm. For the samples of 1,000mm the reduction is 45.5 per cent. Measuring specific time of piping with a tape piper and without it show that the value of this processing parameter is reduced by introducing the attachment, the reduction varying from 31.0 to 64.5 per cent. The results in Figure 6 show that the average stitching speed of the sewingmachine in changing the sample length from 300 to 1,000mm, for the stitching speeds of 1,500 and 2,500rpm, and without a tape piper, is reduced by 6.8 per cent and 11.6 per cent respectively, while the reduction for the stitching speed of 3,500 and 4,700rpm is higher by 51.8 per cent and 9.3 per cent. When a tape piper is used, the resulting diagram of sewing-machine average speeds is as depicted in Figure 7. The results obtained show that the increase in sample length (from 300 to 1,000mm) yields higher average stitching speeds, the range of increase being from 8.1 to 35.4 per cent. The investigation of average stitching speeds using a tape piper and without one shows that the speeds are higher when a tape piper is used, the range of increase in speed being from 6.8 to 68.4 per cent. Pre-programmed sewing speed is sooner reached when using a tape piper and maximum speed can be retained longer, as the auxiliary devices make the guiding of the workpiece easier, which is the most important factor in defining the average stitching speed of a sewing-machine. Depending upon the fabric characteristics (thickness, flexibility, rigidity, initial recovery angle) and the measuring sample length, the operations of piping and hemming, without auxiliary devices and with them, were performed on a particular number of segments, as can be seen in Table IV. Sample length, l/mm
Table IV. Number of seam segments as dependent upon sample length
300 400 500 700 1,000
Without 2 3 4 6 9
Piping
With
Without
1 1 1 1 1
2 2 3 5 6
Hemming
With 1 1 1 1 1
Employing the MTM system and analysis of basic movements show that in Impact of piping the measuring sample using a tape piper the attachment makes seam auxiliary devices formation easier, eliminating the sets of movements 1, 2, 3 and 4, as well as set 7 (performed during the break in sewing). Only the sets of movements described as transporting to the needle (mM12C) and positioning under the needle (P1SE), with total duration of 15.4TMU (0.55s) are used for the operation 261 of piping the measuring sample using a tape piper. When the operation is performed with a tape piper, it is not necessary to tuck-in the ribbon additionally (2) or to align it (4 and 7), as it is done by the attachment. The result is that sewing is done in a single segment for all the measuring sample lengths, as seen in Table IV. Taking into account the method of performing the operation with the auxiliary device, this operation is classified as less complex, making the worker's training shorter. If the operation is performed without a tape piper, the worker's psychological and physical abilities should be rather high, as it is a complex operation under these conditions, and higher accuracy is required (1mm). Application of a tape piper in garment manufacturing processes reduces the basic time for the operation, makes a uniform rhythm of performing the sub-operations and the whole operation possible, which results in higher seam quality, as well as reduced fatigue and loading on the part of the worker. Results obtained show that the basic time necessary for performing the operation is reduced by introducing a hemmer, the reduction being in the range from 11.1 to 38.3 per cent. The same parameter is also reduced by increasing the stitching speed of the sewing-machine used. If the speed is increased from 1,500 to 4,700 rpm, basic time necessary for the operation will be reduced in the range from 20.8 to 41.9 per cent. The results obtained for the degree of sewing-machine utilisation show that this parameter is higher for the operations which include the usage of a hemmer, increase being as high as 59.8 per cent. The degree of sewing-machine utilisation is also increased with longer measuring samples, increase being from 9.5 to 64.5 per cent. Investigation of sewing-machine utilisation, as related to varying the machine speed, reveals that the machine utilisation is reduced by increasing the speed, the reduction being in the range from 30.6 to 57.0 per cent. Results of variations in specific sewing time, related to the whole of the operation, show that specific time is shorter for the operation with a hemmer (for all the sample lengths and stitching speeds), the reduction being in the range from 7.8 to 44.7 per cent. Increasing the stitching speed results in reduced specific sewing time, the reduction being in the range from 14.8 to 49.8 per cent. The results obtained indicate that the average stitching speed in the course of performing machine and machine-hand sub-operations is higher for the hemming operation with a hemmer, the increase being in the range from 4.3 to 45.9 per cent. It can also be seen that in a sewing operation without a hemmer increased length of the sample (from 300mm to 1,000mm) results in an increased average
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stitching speed, the increase being between 2.5 and 11.4 per cent, while the same increase for the operation with a hemmer is between 5.0 and 37.1 per cent. Analysis of the method of work employed, as well as the analysis down to the level of basic movements, using the MTM system for the operation of hemming without a hemmer (Table III) and with it, show that the usage of the attachment reduces the basic time needed for the operation, reduces fatigue and loading of the worker, as well as the necessary degree of muscular and visual control of the movements. The operation is less complex when the auxiliary device is employed, and it does not ask for higher psychic and physical abilities on the part of the worker, which means that the pool can be broadened regarding the age and skill of the workers available. The analysis of basic movements in the operation of hemming using a hemmer show that in positioning the workpiece only the set of movements mM12C/P1SE (14.4TMU) is used, as the attachment makes seam formation easier in a single segment for all the measuring sample lengths, as seen in Table IV. 5. Conclusion The investigations performed into the impact of tape piper and hemmer on sewing operation processing parameters, analysis of the results obtained as well as the above discussion, all lead to the conclusion that using a tape piper the time necessary to perform the operation is reduced from 27.2 to 61.2 per cent, sewing-machine utilisation degree is increased from 14.8 to 110.6 per cent, specific sewing time is reduced by from 31.0 to 64.5 per cent, while the average sewing-machine speed in performing machine and machine-hand suboperations is increased from 6.8 to 68.4 per cent. Application of a hemmer reduces the duration of the operation from 11.1 to 38.3 per cent, increases the sewing-machine utilisation degree by as high as 59.8 per cent, reduces the specific sewing by time from 7.8 to 44.7 per cent, while the average sewingmachine speed in performing machine-hand sub-operations is increased from 4.3 to 45.9 per cent. Analysis of the method of work, operation structure, as well as the MTM analysis of the basic movements, all lead to the conclusion that the application of auxiliary devices increases the degree of movement co-ordination in performing the operation, as basic sets of movements are performed with a higher degree of dynamics (types 2 and 3). Application of auxiliary devices also means shorter training time, as unfavourable simultaneous movements of Class III are substituted by movements of Classes I and II, much more favourable for the worker, the rhythm of their performance is more uniform, while the degree of necessary muscular and visual control is reduced. Other sets of movements included in performing the operation with auxiliary devices can be performed outside the central field of sight of the worker. The operations performed using auxiliary devices are less complex and do not ask for a higher degree of sensory and motoric abilities on the part of the worker, which means that the selection of the workers is much easier, especially regarding their age and skill. All the above factors have a considerable impact on the fatigue and
loading of the worker. Using auxiliary devices makes the structure of the Impact of operation more favourable, basic time necessary for its performance shorter, auxiliary devices while the degree of machine utilisation is increased, as well as productivity per hour. References DragcÏevicÂ, Z. et al. (1997), ``Investigation of operative logical movement groups in garment sewing'', in Gerak, J. (Ed.) 2nd International Conference Innovation and Modelling of Clothing Engineering Processes IMCEP '97, Faculty of Mechanical Engineering, Institute of Textile and Garment Manufacture Processes, University of Maribor, Maribor, pp. 147-54. DragcÏevicÂ, Z. et al. (1998), ``Contemporary investigations in the field of ergonomy in garment production processes'', Tekstil, Vol. 47 No. 2, pp. 81-9 (in Croatian). DragcÏevicÂ, Z. et al. (1999), ``Mathematical model of interaction of sewing processing parameters'', in Katalinic, B., (Ed.), 10th International DAAAM Symposium, DAAAM International Vienna, Vienna, pp. 127-8. GersÏak, J. and SÏaricÂ, A. (1995), ``Objective evaluation of a stabilized garment parts handle'', International Journal of Clothing Science and Technology, Vol. 7 No. 2/3, pp. 102-10. Hursa, A. (2000), ``The impact of auxiliary devices on sewing-machines on process parameters of garment manufacturing operations'', Master's thesis, Faculty of Textile Technology, University of Zagreb, Zagreb (in Croatian). Rogale D. (1995), ``Garment sewing processing parameters: determination using mathematical methods and computers'', International Journal of Clothing Science and Technology, Vol. 7 No. 2/3, pp. 56-60. Rogale, D. and DragcÏevicÂ, Z. (1997), ``Portable computer measuring systems for automatic process parameter acquisition in garment sewing processes'', in Gerak, J., (Ed.) 2nd International Conference Innovation and Modelling of Clothing Engineering Processes IMCEP '97, Faculty of Mechanical Engineering, Institute of Textile and Garment Manufacture Processes, University of Maribor, Maribor, pp. 47-55. Rogale, D. et al. (1997), ``Processing parameters of garment sewing operations during flat seam joining'', Tekstil, Vol. 46 No. 2, pp. 81-9 (in Croatian). Stylios, G. et al. (1996), ``Modelling the dynamic drape of garments on synthetic humans in a virtual fashion show'', International Journal of Clothing Science and Technology, Vol. 8 No. 3, pp. 95-112.
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Investigation of dynamic working zones and movements in garment engineering Zvonko DragcÏevic and SnjezÏana FirsÏt Rogale
Faculty of Textile Technology, Department of Clothing Technology, University of Zagreb, Zagreb, Croatia Keywords Garment, Ergonomics, Movement Abstract A new measuring system for three-dimensional video recording is described, together with its application and possibilities in investigating dynamic working zones in garment manufacturing processes, employing a kinematic method. A video recording can be processed as a series of static frames or as a dynamic series of recordings, employing a system for video recording and storing the recordings from three planes (ground plane, side view and frontal representation of a workplace). Static zones are created by movements of levels one to four, while dynamic zones are created with the help of the whole body, using movements of levels five and six. Processing is done using a contemporary computerised system, software for processing video recording and software for image processing. The new measuring system presented works together with the measuring system for the processing parameters of garment sewing operations, and enables the investigator to work on movement cyclograms and dynamic working zones, depending on the processing parameters, operation structure and workplace designing. Results obtained relevant for the investigations in garment engineering processes are described, with the emphasis on work study and workplace designing in the garment industry ± the need to measure spatial values (angles, distances, dimensions etc.), temporal values (duration of the movements, movement trajectories, acceleration etc.). The process of creating a cyclogram for the graphic presentation of movements is also presented.
International Journal of Clothing Science and Technology, Vol. 13 No. 3/4, 2001, pp. 264-279. # MCB University Press, 0955-6222
1. Introduction Processing parameters in garment manufacturing processes have been intensively investigated in the course of the research project Garment Manufacturing Processes and Design, financed by the Ministry of Science and Technology of the Republic of Croatia. The measuring system applied is based on two independent parts used for measuring and acquisition of the duration of processing parameters, on the one hand, and a bi-plane system of camcorders, on the other. The measuring system is equipped with four measuring sensors, which measure simultaneously and in a non-contact manner the following: rotation time and speed of the main shaft (reflection of IC rays), arm movements within the limited part of the working space in the zones of taking and laying-off (active microwave sensor), pedal regulator movements (potentiometer), by which the whole of the sewing dynamics is controlled and managed (Rogale, 1995; DragcÏevic et al., 1997). The existing system has been complemented with the system spatial, 3D simultaneous video recordings of workplaces. Workplaces have been recorded using three camcorders, so that ground plan, side view, and frontal representation of the workplace can be analysed (Figure 1).
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Figure 1. System for 3D measurements and analysis
Initial results of these investigations were published as early as 1990, at the International Conference for Engineering Design (Rogale and DragÏcevicÂ, 1990). Further investigations were done with considerably broadened measuring equipment potential and simultaneous miniaturisation of the system (Rogale and DragÏcevicÂ, 1997). Together with processing parameters, sets of optimal logic movements in performing garment sewing operations were also investigated (DragÏcevic et al., 1997), time norms were set on the basis of measuring processing parameters (Zavec et al., 1999) and simultaneous measurements of processing parameters and sets of logic movements were performed (DragÏcevic and Rogale, 1999). Further development in employing the equipment mentioned is described here. The original method of 3D simultaneous video recording and analysis of the recording was developed, together with the possibilities of measuring and defining a number of spatial and temporal values. Cyclograms of body and limb movements of the workers were made in the course of performing sewing operations. Employing these movement cyclograms, it is possible to investigate movement trajectories, as well as some dynamic changes, such as the speed of particular parts of workers' limbs and their acceleration. The whole new area of investigating biomechanical characteristics of kinematic structures of the worker's body in performing sewing operations is thus opened.
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Original procedures and methods are also presented for obtaining particular results by employing the method described, necessary for establishing and investigating the model of work at a workplace. Special emphasis is given to adequacy and availability of the equipment used, so as to make the method described available to other researchers in this or associated fields.
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2. Measuring system and equipment Actual recording of sewing was done in the course of the experiment, using a multiplane system of camcorders, and results obtained analysed using the kinematic method established. Measurements were done in the laboratory of the Department of Clothing Technology, Faculty of Textile Technology, University of Zagreb. At a designated workplace, the operation of sewing a side seam of the legging of men's trousers was recorded, as performed by y female industrial worker, 158cm tall, 57kg mass, of average statistical and dynamic anthropometric measurements. A trial recording of the operation (np = 5) established a workplace stabilisation coefficient (Ks = 0.20), while coefficient of involvement (Kps = 1.10) was established on the basis of the estimation of the speed and co-ordination of movements, accuracy of performance and application of adequate method of work. Measurements were done at the environmental temperature of 24ëC, with relative humidity of 51 per cent. Universal sewing-machine Brother, designated DB2-B755-403A-MARK III, equipped with a processing computer F-100, was used for sewing operations at the workplace designed for the purpose. It is a single-needle sewing-machine, sewing with double lockstitch type 301. The workpiece is pulled using underfeed, and the machine is used for sewing medium-weight fabrics. Maximum main shaft rotation speed is 4,700rpm, realised with the help of a Brother's single-phase electronic AC servomotor, model MD 601, of 400W. Nominal rotation speed of the shaft can be programmed by the F-100 microcomputer. In the course of the investigation described, nominal stitching speed selected was 4,000rpm, with stich density of 4cm-1. Total seam length was 1,120mm, and it was manufactured with two consecutive sewing segments. Following the workplace stabilisation coefficient (Ks = 0.20), basic recording was done in a series of 18 consecutive sewing operations. Characteristic body postures were selected for the presentation of the results, as contained in two sets of movements: (1) Movements of forward flexion in sagittal plane (set of movements from starting the sewing-machine and hand-machine sub-operation of sewing the second segment of the seam). The body occupies ergonomically unfavourable posture, including elevated interabdominal pressure and loading of lumbar and cervical section of the spine. (2) Backward movements, included in returning the body into a balanced (medial sitting) posture.
This series of sets of movements is repeatedly performed in the course of sewing operations. The above movements are ergonomically highly unfavourable, due to short cycles of performing sewing operations (28-34s) and high frequency of their repetition. They result in unacceptable fatigue, reduced visual and muscular concentration and, finally, in professional diseases in lumbar, thoracic and cervical sections of the spine (Burton, 1986; Deuretzbacher and Rehden, 1995). An IBM compatible personal computer was used to extract spatial values. Its characteristics were as follows: Pentium II processor, 266MHz working frequency, 64MB RAM memory, ATI Wunder PRO graphic chart with the possibilities of video signal input and output (4MB), 6GB hard disk, 19-inch colour monitor and sound chart. A camcorder and colour printer were also used, together with the software for video recording input into the computer, its conversion and storing on to the disk, software for surveying video recording and selection of individual frames from the series, as well as adequate software for image processing, storing and printing. 3. Results and discussion In this chapter, the results are presented of defining spatial values, obtained on the basis of the analysis of the results of kinematic method applied, as well as the results of defining temporal values, of defining cyclograms, series of ergonomically unfavourable sets of movements (Murphy, 1992). 3.1 Defining spatial values on the basis of video recordings, using a computer Spatial variables were measured by the way of computer analysis of the video recording, from which individual static frames were selected. Any of the commercial software packages for computerised display and analysis of video recordings can be used to separate static frames (such as Adobe Premier 4.0 or 5.0, by Adobe Systems (CorelDRAW 7) or some other). Static frame selected is separated and transferred into a software for image processing (e.g. PhotoShop 4.0, by Adobe Systems Incorporated, CorelDRAW 7, CorelPHOTO-PAINT 7, CorelXARA by Corel Corporation or some other). In the course of the investigations described here, spatial variables were measured using CorelDRAW 7 (McClelland, 1999). 3.1.1 Setting the scale. Measures on static frames should be set in short intervals, regardless of the fact that the procedure is not simple, as the static frame of a video recording is made smaller, and the real scale is not known. Furthermore, a sphere length is reduced to a planar one. Previous investigators have already introduced the method of calibrating equidistance of horizontal and vertical video recording and using spatial correction factors by employing special grids (DragcÏevic et al., 1998). Recent investigations have shown that dimensions can be measured in a much simpler way later on, retaining a high degree of accuracy, if the sets of movements involved are performed in a plane. A variant of CorelDraw 7 has the option entitled Grid & Ruler Setup, where auxiliary measures can be set in one of the measuring units offered (inch, foot,
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mile, millimetre, centimetre, meter, etc.), and a sub-option entitled Edit Scale, where one of the measures offered can be easily selected, or a working scale can be constructed on individual static frames. Constructing one's own scale is suggested, as it is quite easy to do, if at least one of the dimensions of an object recorded is known, e.g. the length of the machine working plate is known to be 105mm, and is on the computer monitor 124.3mm long. These two pieces of information are enough for the computer to calculate the scale for the case in question, as well as to adapt a vertical and horizontal auxiliary ruler, which will later on be used to simplify measuring necessary dimensions on a static frame. 3.1.2 Distance measured. Distance measurements, together with marking the values measured, are done after the scale is set. There are various options of measuring and marking horizontal, vertical and inclined distances and dimensions, according to the scale developed. In the process, marks are inserted and values measured in the selected measuring technique and of adequate accuracy are written in. Figure 2 shows the manner of computerised measuring and marking distances based on selected side-view static frame from a video recording.
Figure 2. Measuring and marking distances by processing a static frame from a video recording using a computer
Scale is adapted according to the markers positioned on the edge of the sewingmachine working surface, 550mm away from each other (Figure 3a). The distances of the front edge of the sewing-machine and the distance of the worker's arm, from the shoulder joint in taking the workpiece, are then measured and marked (Figure 2a), and also at the moment of the maximum forward bending movement in taking the workpiece (Figure 2b). These values can be read off, for the purpose of extracting variables, or even marked and printed.
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3.1.3 Measuring angles. Angles were measured using the software Angular Dimension Tool, intended for measuring angles. Its accuracy can be adjusted from 1ë to (101ë). The measuring can be done in angles, radians or grades. In the course of the measurement, the computer can arrange one of the angle arms horizontally, and the other as a string, connecting two points, e.g. two markers selected on the worker's spine (Figure 3). The example of measuring angles is represented by two separated static frames of the side video recording the operation in the initial taking of the workpiece (Figure 3a), and with the maximum forward incline in the course of actual sewing operation (Figure 3b), when the left arm is maximally stretched. The examples of measuring angles on the lumbar and cervical sections of the worker's spine are presented. The angles measured can be either read off on the
Figure 3. Measuring angles of the curve on lumbar and cervical sections of the spine, using a computer
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screen, for the purpose of extracting variables, or incorporated into the static frame of the video recording. These angle values, incorporated into the frame, together with the marks of the vertebrae selected, can be superimposed one over the other, employing the procedure of translating and positioning them into the same characteristic point (e.g. lumbar section of the spine). A parallel presentation of the shifts of body parts or limbs can be obtained in this way. Figure 4 shows only two superimposed and translated angles from the presentation in Figure 3. All the changes of characteristic spine angles can be presented in a similar way, together with a cyclogram of the changes in question. 3.1.4 Measuring horizontal and vertical zones of sight. Angles making vertical zones of sight can be superimposed on to the static frames of the side view and ground plan, with characteristic angles of transferring the central line of sight within maximal and comfortable rotation of the eye, head and eye/head as a unit. Vertical zones of sight, as seen in Figure 5a, can be superimposed on to the side view recording. The maximum usable vertical field of sight for a clear view in the course of the sub-operation of taking the workpiece is given. It is also possible to superimpose horizontal zones of sight, as seen in Figure 5b, on to the ground plan representation selected, with maximal and optimal horizontal zones of sight for a clear view are clearly seen. The technique of measuring and drawing the necessary vertical and horizontal zones of sight is also used to check the adequacy of workplace design and adequate degree of concentration of sight, as well as the distribution of the zones of clear view and the zones of central and outer field of sight. These pieces of information are essential in developing the appropriate method of work, as they define the possibility of performing simultaneous, combined and synchronised movements. 3.2 Methods and results of defining temporal values on the basis of video recordings It is necessary to select one of the three possible spatial representations, preferably the one in which the movement analysed can be best observed. The video recording is, from the recorder, through the card in the computer,
Figure 4. Presentation of extracted and superimposed movement of the spine from Figure 3
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Figure 5. Measuring and analysis of (a) vertical and (b) horizontal zones of sight using a computer
digitised and stored on the hard disk. The work is continued by applying a software for processing a video recording (e.g. Adobe Premier 4.0 or 5.0 by Adobe Systems Incorporated). In most cases, it is possible to process 24, 25 or 30fps. The video recording stored in the computer can be analysed in a continuous series of individual frames, as it is done on a video recorder, but it is also possible to search the recording by shifting the indicator to the initial point of the movement measured. Precise positioning (1fps) is possible by using cursor keys. Presentation of temporal values is given below the indicator and in the following format: hour, minute, second and frame number in the series. Basic duration of a movement is the difference between the flow times. Accuracy of the read-off depends upon the rate of recording, and is 0.04s for the recording speed of 25fps. Speed of a movement is measured indirectly. It is necessary to extract spatial variables of the length of the movement, as well as its temporal variables. The speed can be calculated using the following equation for speed (vp): vp
lp tp
1
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where: lp is the length of the movement tp is the duration of the movement. In principle, the speed measured in the above way is a projection of the vector of speed upon the recording plane. In the area of garment technology, it satisfies the purposes of movement analysis in sewing operations, where the arms are positioned in the plane of the working plate of the machine. Ground plan presentation of the workplace is quite adequate for the purpose. Equation (1) satisfies the need for evaluating the total speed of the movement, but it cannot differentiate between the phases of acceleration and deceleration in performing a movement. A movement as a whole can be separated into a number of discrete shifts, which is the same as the number of frames recorded for the movement. For example, a movement lasting 1.24s, and recorded with the rate of 25fps, has 31 static frames by which it can be analysed, meaning that it can be separated into 31 discrete shifts. Based on these shifts, it is possible to calculate 31 different speeds for individual shifts for 31 temporal intervals of the performance of the movement. The procedure is rather long and complex, but it makes possible a comprehensive analysis of the nature of a movement and its precise representation, including the phases of acceleration and deceleration. Measuring the trajectory of a movement is interesting from the point of view of work-study and the application of the methods of predetermined times. The three-dimensional video measuring system described above can also be used to define movement trajectory, as the frames obtained by it represent the projections of the movement in frontal, sagittal and transversal planes. Discretisation of the movement is also possible here and the number of discrete elements of the movement trajectory will again depend upon the quotient of the movement duration and the rate of recording. Discrete element of the trajectory (lp can be calculated as follows: q
2 lp
xn1 xn 2
yn1 yn 2
zn1 zn 2 where each expression in brackets is a projection of a section of the trajectory on to one of the planes of recording, while the element designated n relates to the actual static frame and the element designated n + 1 to the following static frame in the series. The whole of the trajectory is obtained by adding all the discrete elements. Acceleration of the movement can be determined employing the kinematic method proposed by using the expression in which the movement acceleration ap is the derivation of the speed of the movement vp in the time of its performance tp, or: dv ap p
3 dtp
As video recording can be done at the rate of 25fps, the changes in speed are rapid enough, or short enough, for the following to be valid: vp ap
4 tp where:
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xn1 vp tn1
xn tn
5
t p tn1
tn
6
and Substituting Equations (5) and (6) into Equation (4), the following is obtained: xn1 xn ap
7
tn1 tn 2 Equation (7) makes it possible to define the projection of the movement acceleration on the X-axis, on the basis of static frames from the video recording. Similar procedures can be used to define the projections on the Yand Z-axes, which makes spatial acceleration. The way in which Equations (5) and (7) are used is shown in the following chapter dealing with determining speed and acceleration of the worker's left hand in the course of sewing. 3.3 Methods and results of defining cyclograms for a graphic presentation of temporary dependent variables Working zones of normal and maximum reach are developed and designed in ergonomical workplace designing procedures (Figure 6), based on average sitting posture and the positioning of shoulder joints. Defining a movement cyclogram is done on a series of frames recorded. Using the software packages mentioned it is possible to superimpose a static frame of the zones of normal and maximum reach upon the existing video recording. The position of the zones does not change, which is also the case with the other equipment at the workplace. The analysis of the recordings shows that the only moving elements are the worker's limbs and the workpiece. Based on the contours of the zones superimposed, it is possible to analyse the adequacy of the workplace design, by checking cyclic sub-operations in the zones of normal reach, and periodic sub-operations in the zones of maximum reach. Figure 6a shows a ground plan of workplaces and working zones in taking the workpiece from the worker's lap, Figure 6b the moment of starting sewing the first segment of a seam, and Figure 6c completion of sewing the first segment of the seam with the worker's left arm maximally extended. It can be clearly seen that most of the movement is performed within the adequate zones, but
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Figure 6. Representation of static working zones of normal and maximum reach in the course of performing sewing operation
the marks on the worker's shoulders are quite far away from the source points of shoulder joints in the zones of normal and maximum reach drawn. The points of shoulder joints do not match even at maximum forward incline of the body, as seen in Figure 6c. Basic analysis of the recording indicates that unfavourable positioning of the bundles in the worker's lap causes increased flexion of the body.
Superimposing the zones of normal and maximum reach so that the source points of the shoulder joints are fixed on the shoulder marks of the worker, a representation of dynamic zones is obtained, where position is changed according to the changes of the posture of the worker's body. This type of representation is appropriate for analysis of body flexion and rotation, as seen in Figure 7.
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Figure 7. Representation of dynamic working zones of normal and maximum reach in performing a sewing operation
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Figure 8. Representation of chain marks of the kinematic system of left arm movement in the posture of forward flexion
Figure 9. Movement cyclogram of the left arm kinematic system in analysing the sets of movements involved in sewing (a) a seam segment, (b) variable position of the hand: 1-9 and (c) trajectory of the hand movement
Analysis and defining movement cyclograms are also essential for proper investigation of movement trajectories, speeds and accelerations, making possible the investigation of biomechanical characteristics of work at a workplace. Chain marks of the points on the worker's limbs are used to define cyclograms. Figure 8 shows the system of chain marks of the right and left joints, taken on the elbow, wrist and hand. Chain marks are separated from individual recordings and are superimposed on to the new drawing of the cyclogram for a set of movements. Figure 9 shows the position of shoulder marks of the right (I) and the left (II) shoulder joint, elbow (III) and hand (IV), as well as the cyclograms of nine projections of chain marks for the forward movement, starting in point 1 at the beginning of sewing, and ending in point 9, at the completion of the seam segment, at the moment when the worker's left arm is maximally extended (Figure 9a). It is possible to superimpose the trajectory of the hand (Figure 9b), on to the cyclogram obtained in the above way, at the point of hand mark. Additional extraction makes possible superimposing and quantification of the hand movement trajectory in the course of moving the arm forwards
(Figure 9c). Similarly, a cyclogram for eight chain marks in moving the arm in the backwards direction can be defined (Figure 10a), hand trajectory can be superimposed, Figure 10b and hand movement trajectory extracted (10 to 17) (Figure 10c). Employing the methods described of finding the position, determining distances and time, it is possible to extract the data on movements of individual marks, which are then mathematically processed according to Equations (1) to (7), with the aim of establishing the speed of the movement in question and acceleration of particular workers' limbs. Recording was done at the rate of 24 fps, meaning that the duration of each frame was 1/24s, or 0.0417s. As the forwards movement (forward flexion) is the movement done in sewing a seam segment, the speed of its performance depends upon the sewing speed and necessary visual and muscular control of movement in guiding the workpiece. The length of the movement (hand trajectory) will be approximately the same as the length of the seam. The movement is performed with a single degree of freedom. Every fifth static frame recorded was used in defining the cyclogram, which means that each change in the cyclogram equals 0.208s. The movement backwards, in returning into the balanced posture (medium sitting) is spontaneous, and is performed much faster. This is why every third static frame was analysed, in the time interval of 0.125s. The results of the extraction of the duration and the length of the movement of the mark of the worker's hand are necessary to calculate and
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Figure 10. Movement cyclograms of the left arm kinematic system in analysing (a) sets of movements backwards, (b) variable position of the arm: 1017 and (c) hand movement trajectory
Figure 11. Graph depicting speed and acceleration variations of hand movements in performing a series of sets of forward movements (forwards flexion) and backward movements (returning into a balanced position) in sewing suboperations
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draw the speed, and then to make the movement speed diagram in time, vp = f(t). Movement acceleration is calculated from the speed differences and time necessary to take samples of static frames. These values are used to make movement acceleration diagrams in time, ap = f(t). Figure 11 shows movement speed and acceleration diagram, obtained by extraction of the variables of time and sections of the shift on the movement trajectory of the worker's left arm, using also calculations of speed and acceleration done afterwards. To calculate efficiently the speed and acceleration of the movements of workers' limbs, a table calculator can be used (e.g. Excel), and to draw the diagram of functions one of the software package for statistics (e.g. Statistica). Cyclograms or diagrams of changes in characteristic angles made by particular parts of the worker's limbs can be measured and constructed in a similar fashion. 4. Conclusion The paper presents all the characteristics of the new kinematic method for assessing success in workplace designing and performing the work, using the techniques of three-dimensional video recording, as well as the results obtained by the method. It should be noted that the method is based on a rather widely available technique of multi-plane video recording, conventional IBM compatible personal computers and commercially available software packages, which makes it widely applicable for laboratory and industrial investigations in the field of garment engineering, and in other areas as well. Using the method presented it is possible to measure spatial values based on ground plan, side view and frontal video recording of a workplace, such as angles, positions, distances, spaces, dimensions etc. It is also possible to measure temporal values, such as duration of particular movements, average speed of moving individual limbs, flexion and rotation of the body, calculate movement trajectories etc. Of special interest are the methods of defining movement cyclograms of parts of limbs, as well as the calculation of the projections of movement speeds, which is a basis for further investigation into finding optimal movements with lowest possible energy consumption and lowest content of mechanical work. It can result in engineering quantification of the success of work and workplace design, including reduced fatigue in performing operations in garment manufacturing. References Burton, A.K. (1986), ``Measurement of regional lumbar sagittal mobility and posture by means of a flexible curve'', in The New Ergonomics of Working Posture, Models, Methods and Cases, Taylor & Francis, London and Philadelphia, pp. 91-9. CorelDRAW 7 user manual 1-Version 7.0 (1999), Corel Corporation, Corporate Headquarters, Ottawa, Ontario, Canada. Deuretzbacher, G. and Rehder, U. (1995), ``A CAE based approach to dynamic whole-body modelling ± the forces acting on the lumbar spine during asymmetric lifting'', Biomedical Technik, Vol. 40 No. 4, pp. 93-8.
DragcÏevicÂ, Z. and Rogale, D. (1999), ``Simultaneous measurements of processing parameters and logical movement sets in the garment industry'', Proceedings of 9th International DAAAM Symposium, 21-23th October, Vienna Austria. DragcÏevicÂ, Z., Rogale, D. and Trgovec, L.J. (1997), ``Investigation of operative logical movement groups in garment sewing'', in Gerak, J. (Ed.), 2nd International Conference Innovation and Modeling of Clothing Engineering Processes, IMCEPÂ 97, 8-10 October, Maribor, Slovenia, pp. 147-54. DragcÏevicÂ, Z. et al. (1998), ``Contemporary investigations in the field of ergonomy in garment production processes'' (in Croat.), Tekstil, Vol. 47 No. 2, pp. 81-9. McClelland, D. (1999), Photoshop 4 Bible, Edition Znak, Zagreb, Croatia. Murphy, G. (1992), ``Adjust to avert injury'', Apparel Industry Magazine, March, pp. 64-71. Rogale, D. (1995), ``Garment sewing processing parameters: determination using mathematical methods and computers'', International Journal of Clothing Science and Technology, Vol. 7 No. 2/3, pp. 56-60. Rogale, D. and DragcÏevicÂ, Z. (1990), ``Methods of measuring process parameters on designed workplace in clothing industry'', Proceedings of International Conference on Engineering Design, Dubrovnik, Croatia, 28-31 August, Vol. 3, pp. 1689-96. Rogale, D. and DragcÏevicÂ, Z. (1997), ``Processing parameters acquisition and analysis in garment production operations'', Proceedings of 8th International DAAAM Symposium, 23-25 October, Dubrovnik, Croatia, pp. 287-8. Zavec, D., DragcÏevicÂ, Z., Rogale, D. and GersÏak, J. (1999), ``Investigation of the structure and processes parameters of sewing operation'', AUTEX Research Journal, Vol. 1 No. 1, pp. 39-46.
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Porosity and air permeability of composite clean room textiles JirÏÂõ Militky and Marie HavrdovaÂ
Department of Textile Materials, Technical University of Liberec, Liberec, Czech Republic Keywords Textiles, Protection Abstract It is well-known that clean room textiles are acting as a barrier protecting humans against the surrounding atmosphere or vice versa. These textiles are produced in the limited range of porosity and the air permeability. The porosity calculated from fabric geometry and the air permeability of two typical clean room textiles of Czech production are measured. The variation of air permeability is described by the analysis based on the coefficient of variation and spatial autocorrelation. The air permeability of composite textiles of multiple layers is predicted from a simple model. This model is based on the idea of a combination of air pressure drop in individual layers. The predicted air permeability is compared with experimental measurements.
1. Introduction It is well-known that so-called clean room textiles act as a barrier protecting humans against the surrounding atmosphere or vice versa. These textiles are mainly used for special clothing. It was shown that in the clean rooms there has to be pollution below 100CFU/m3 (CFU means colony forming units). The clean room textiles are produced in the limited range of porosity and air permeability. The comfort of these textiles is often quite unsatisfactory. Generally, clean room textiles have to satisfy the following requirements: . protect the atmosphere against particles emitted from the human body (particle barrier) . protect the atmosphere against particles produced from clothing . protect the human body against dust particles (carriers of micro-organisms) from the atmosphere. In this contribution the porosities calculated from fabric geometry and air permeability of typical clean room textiles of Czech production are measured. The variation of air permeability is described by the analysis based on the coefficient of variation and spatial autocorrelation coefficient. The simple model for prediction of the air permeability through a multiple layers composite structure is proposed. International Journal of Clothing Science and Technology, Vol. 13 No. 3/4, 2001, pp. 280-288. # MCB University Press, 0955-6222
This work was supported by the Czech National Grant Agency (grant No. 106/99/0372), Czech Ministry of Education Grant (grant No. VS 97084) and research project J11/98:244100003 of the Czech Ministry of Education.
2. Fabric porosity evaluation Porosity and air There exist three basic techniques for characterization of the idealized fabric permeability porosity PI from some construction parameters of weaves (Militky et al., 1998). Classical parameters are sett (texture) of weft DC [1/m], sett of warp DM [1/m], fineness of weft yarn TC [tex], fineness of warp yarn TM [tex], planar weight of weave WP [g/m-2], density of fibers rF [kg m-3] and thickness of fabric tW [m]. 281 A. Density based porosity PW is computed from the equation: PW W = F
1
where rW is volumetric density defined by: mV WP 2 W vV tW
2
where mV [g/m-3] is volume weight of fabrics equal to the WP/tW and vV [m3] is the volume of fabrics having a surface of 1m2. From the measured planar weight WP, fabric thickness tW and known density of fibers it is simple to compute the ``real'' porosity: WP PW
3 2 F tW B. Porosity based on the hydraulic pore definition PHW is defined as: volume covered by yarns vY PHW 1 1 whole accessible volume vV
vY tW
4
The VY is equal to the sums of volume of weft yarns SUC and warp yarns SUM: VY SUC SUM
5
SUC DC v1C
6
SUM DM v1M
7
where:
Here the v1C and v1M are volumes of weft and warp yarn in the 1m portion of fabrics: TC v1C lC dC2 = 4 lC 3
8 10 C for v1M the indexes C are replaced by the indexes M. For the case of rFC = rFM = rF can be porosity PHW expressed by: 1:1 10 6 DC TC DM TM
9 PHW 1 F tM
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C. Porosity based on the cover factor PCF is derived from the pure geometry of yarns projection. Classical Pierce definition of CF is computed from the idealized projection of fabric: CF DC dC DM dM
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dC dM DC DM
10
Porosity is then defined by: PCF 1
CF
11
For the idealized circular yarn with the same packing density it is simple to compute diameters from: p 2 TC
12 dC p 103 C dM
p 2 TM p 103 M
13
Here rC and rM are unknown densities of weft and warp yarns. These densities are combinations of densities of fibers rF and air rA according to the packing of fibers in yarns. The values rC and rM are therefore function of twist and method used for yarn creation. For the moderate level of twist it has been empirically found that: F = C 0:525
14
and this correction can be imposed to Equation (12) for computation of dC. The same procedure can be adopted for computation of dM. More realistic are elliptical shapes of yarns. 3. Porosity and permeability Let the textile fabric be assumed to be a porous sheet of thickness tw. The pressure drop Dp = pprÏed-pza of air going through this sheet can be described by the Carman Kozeny or more realistically by the drag model. In the drag model Dp can be expressed by the combination of viscous and inertial contributions: p=tw A w B w2
15
where w is superficial flow velocity through the sheet. The values of constants A and B depend on the assumptions about nature of flow and nature of pores. The total pressure drop can be simply replaced by the coefficient of pressure drop LP (Cherkassky, 1998): p LP
16 0:5 w2
where r is air density (for dry air at 25ëC is r = 1.175kg/m-3).The pressure drop Porosity and air is dependent on the Reynolds number Re (Cherkassky, 1998): permeability wd Re
17 Po # where d is mean pore (cylindrical) diameter, Po is surface porosity (see Equation (11)) and is air kinematical viscosity. In the standard testing apparatus the mean value of Re % 200. Total pressure drop LP can be described as a function of Re and porosity Po: 1 Po 40 LP
1 Po
18 Re0:75 Po2 This relation is valid from Re % 1(for all porosities) to Re % 103 (for porosities less than 0.5). Gorbach (Cliff and Ord, 1973) derived the semi-empiric: LP k1
k2
1 Po p
Po Po
Po2
19
where k1 and k2 are coefficients dependent on the Re and structure of textiles. For small pressure drops Dp the D'Arcy law is suitable. Air permeability AP is then expressed in the form: w 1 AP
20 SW p Ro tW where SW is the surface area of the textile and Ro is total air flow resistance. Standard testing apparatus has constant SW = 20cm2 and Dp (50 or 200Pa. Air permeability AP is related to coefficient LP: 2 LP 2
21 Sw p AP 2 The relation of air permeability to surface porosity is derived as a combination of Equation (21) and Equations (18) or (19). Total airflow resistance is expressed as: 1 Ro
22 AP tw The resistance of multiple layers can be generally described by the generalized rule of mixing: X Rcm Roim vi
23 where Roi is resistance of the ith layer having thickness twi and m is the parameter defining the rule of mixing. Weighting factor vi is equal to:
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24
i
284
For m = 1 the additivity of resistance is assumed and the resistance Rc of multi layer structure is: X Rc Roi vi
25 For m = 0 the logarithmic rule of mixing of resistance is assumed and the resistance Rc of multi-layer structure is: X Y v ln
Rc ln
Roi vi or Rc Roii
26 i
i
Prediction of air permeability AP for multi-layer structure is simply defined as: 1 P
27 AP Rc twi For N-layer system from the same textile material (with resistance Ro and thickness tw) is Rc = Ro and independently of the mixing rule is: 1
28 AP N Ro tw 4. Permeability uniformity For textiles acting as a barrier against particles permeation it is necessary to ensure not only the mean porosity but also the uniformity of porosity. The uniformity of porosity can be evaluated from air porosity APij measured in the individual cells of rectangular mesh. Mesh used in this work consists of i = 7 rows equal to the number of columns j = 7. For description of uniformity in the weft and warp directions the division of the total coefficient of variation CV can be used. In the work (Cherkassky, 1998) it is derived that CV can be expressed by means of the forms: 2 CV 2 CVO2 CVOU
29
2 CV 2 CVU2 CVUO
30
or Symbol CVO2 means variation coefficient in the warp direction and CVU2 is 2 2 variation coefficient in the weft direction. The symbols CVOU and CVUO mean cross-products variation coefficients.
Permeability variation can be dependent on the location of individual cells Porosity and air (arrangement of measured spots in the plane). This spatial uniformity in the permeability plane can be expressed by the spatial autocorrelation indices. In spatial autocorrelation some measure of contiguity is required. Simple contiguity measures are defined as neighborhood relations. The King's case considering neighborhood of eight cells was used. The 285 connectivity (spatial weight) matrix W contains elements Wij = 1, if the ith and jth cell are in proximity or Wij = 0 if the ith and jth cells are far from each other. Geary autocorrelation index is defined by (Cliff and Ord, 1973): PP Wij
APi APj 2 N 1 i j PP c
31 P 2 2 Wij
APi AP i
j
i
where AP is the arithmetic mean of all cells' permeability. The statistic c is in the range from 0 to 2. Negative spatial autocorrelation is for c > 1 and positive spatial autocorrelation is for c < 1. Mean value is equal to E(c) = 1. Variance D(c) based on the approximate normality is defined as: D
c
N
1
2 S1 S2 4 S02 S02 2
N 1
32
P P Individual symbols in Equation (32) are defined as: S0 i j Wij ; S1 P P P 2 2 1 i j
Wij Wji and S2 i
Wi Wi . 2 Symbol Wi* denotes the ith row and W*i denotes the ith column of matrix W. Random variable: c 1 Z
c p
33 D
c has approximately standardized normal distribution. If absolute value abs (Z(c) 2), the significant autocorrelation occurs. 5. Experimental part The two typical clean room textiles produced by SPOLSIN Company Ceska Trebova Czech Republic were investigated. These textiles are designed for the clean room class of 10. Textiles are weaves composed of polyester fibers. From individual textiles the five samples 10610cm were randomly selected. Basic parameters of textiles are summarized in Table I. Thickness tW was measured at load 0.13kPa. The warp and weft fineness is computed from weights of 10cm long portions of yarns. Yarn diameters were computed from Equations (12) and (13) for the densest arrangements (six neighbors), i.e. F =C 0:907. The air permeability was measured under standard conditions (pressure drop 200Pa).
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The porosities were computed from the Equations described in section 2. Results are given in Table II. The air permeability in the individual cells of the rectangular mesh was measured under the same conditions as individual air permeability. Set of APij was obtained for each textile. The measurement of multiple layers was made in the same way. Results are summarized in Table III. 6. Results and discussion The computed porosities of investigated textiles are in a very narrow range (see Table II). The differences between air permeabilities are also not so high. In our previous investigations the linear dependence between these characteristics has been found (Militky et al., 1998). From the sets of APij values measured on the mesh defined in Figure 1 variation coefficients CVO and CVU were computed. Results are given in Table IV.
Table I. Basic parameters of textiles
Table II. Computed porosity of clean room textiles
Textile
WP [kg/m2]
tW [mm]
TM [tex]
TC [tex]
Aralka Argos
0.102 0.141
0.18 0.25
8.8 17.6
11.5 18.4
Textile
DM [1/m]]
DC [1/m]
dM [mm]
dC [mm]
Aralka Argos
6,400 4,400
3,200 3,000
0.094 0.133
0.108 0.136
Textile
PW
PHW
PCF
Aralka Argos
0.59 0.59
0.59 0.58
0.26 0.25
Source: Meloun et al., 1992
No. of layers
Table III. Air permeability for multiple layers
1 2 3 4 5 6 7 8 9
Aralka[Pa]
Argos [Pa]
25.0 13.2 9.3 7.2 6.3 5.6 5.0 4.2 3.9
19.4 11.1 8.2 6.1 5.4 4.7 4.0 3.9 3.6
The variation coefficients in the warp and weft directions are relatively high. Porosity and air Computed Geary autocorrelation coefficient c, variance D(c) and permeability standardized quantity Z(c) is given in Table V. The random variate Z(c) is very high and therefore the local air permeability exhibits positive autocorrelation. The applicability of Equation (28) for prediction of multiple layers air 287 permeability was tested by linear regression. The model (Equation (28)) was expressed in the form: k y
34 x where y = AP, x = N and K = 1/(Ro*tw). The parameter K obtained by linear least squares, corresponding standard deviation sK and predicted correlation coefficient Rp are given in Table VI. The agreement between model and experimental data is fairly good, as is shown in Figure 1 for Aralka.
Figure 1. Multiple layer air permeability model Y = AP against x = 1/N (Aralka)
Textile
CV (total)
CVO (warp)
CVU (weft)
Aralka Argos
6.36 7.41
5.43 4.74
3.31 5.69
Textile
c
D(c)
Z(c)
Aralka Argos
0.355 0.488
0.0078 0.00828
7.078 5.619
Table IV. Coefficient of variation in the weft and warp directions
Table V. Geary autocorrelation indices
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Figure 2. Smoothed surface of permeability uniformity for Argos
Table VI. Multiple layer air permeability model parameters
Textile
K
sK
Rp
Aralka Argos
26.216 21.12
0.818 0.991
0.973 0.915
More precise results can be obtained by using the general form with intercept but without physical explanation. The nature of variation of permeability is visible from smoothed surfaces. Figure 2 shows the bivariate spline smoothed surface for Argos. Nearly the same form has a smoothed surface for Aralka. 7. Conclusion The porosity and air permeability of clean room textiles were measured. The technique for evaluation of permeability uniformity from local measurements of air permeability on the rectangular array of spots has been proposed. The tested fabrics were non-uniform in both weft and warp directions. The prediction of multiple layer permeability based on the simple mixing rule has been proposed. The final model is suitable for description of experimental data. References Cherkassky, A. (1998), ``Surface uniformity of non-wovens'', Text. Res. J., Vol. 68, p. 242 . Cliff, A.D. and Ord, J.K. (1973), Spatial Autocorrelation, Pion, London. Meloun, M., MilitkyÂ, J. and Forina, M. (1992), Chemometrics for Analytical Chemistry, Vol. 1, Ellis Horwood, Chichester. MilitkyÂ, J., TraÂvnõÂcÏkovaÂ, M. and BajzõÂk, V. (1998), ``Air permeability and light transmission of weaves'', VlaÂkna a textil, Vol. 5, p. 31.
The current issue and full text archive of this journal is available at http://www.emerald-library.com/ft
Study of the relationship between deformation of the thread and built-in fibres Andreja Rudolf and Jelka GersÏak
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Faculty for Mechanical Engineering, Institute of Textile and Garment Manufacture Processes, University of Maribor, Maribor, Slovenia Keywords Threads, Twisting, Mechanical properties, Deformation Abstract Presents the study of the relationship between the deformation of the sewing thread and built-in fibres as a consequence of a thread loading in the sewing process. The influence of the stitching speed and different twist numbers of PES thread on the alteration of the mechanical properties of the fibres twisted in the thread was studied for that purpose. On the basis of the received results it was found that with an increase in the number of the thread twist, the breaking tenacity and initial elasticity modulus of the fibres decrease, while the resulting deformation of the sewing thread between the sewing process was reflected as a decrease in the fineness and breaking extension of the fibres and as an increase in the value of the initial elasticity modulus of the fibres.
1. Introduction The sewing ability of a thread is determined as a relationship between the thread and sewing material in the sewing process and also as its resistance to the technologically conditioned forces in the stitch forming process, which the thread must stand without greater deformations. Analyses of the stitch forming process and acting forces indicate that the thread is exposed to different loadings between the sewing processes (GersÏak, 1986a,b, 1987): . thread load caused by friction and rubbing; . thread bending; . short strike loading; and . tensile loading of a thread which can lead to overloading of the local surface of the thread and therefore to the thread deformation, which can be reflected as changes in mechanical properties of the fibres twisted in the thread. Mechanical properties of the thread, which are influenced with the raw material, construction requirements and finishing, have an important role. Also the number of turns and their angle of inclination have an influence on the mechanical properties of a thread beside the type and fibre quality. As twist is inserted, the fibres or filaments become closer, thread size is reduced and internal force called torsion moment builds up, as well as compression forces that influence the fibres towards the core. Too high a number of turns can cause loading of the fibres in the thread (Eirich, 1969; Harch, 1993).
International Journal of Clothing Science and Technology, Vol. 13 No. 3/4, 2001, pp. 289-300. # MCB University Press, 0955-6222
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2. Relationship between deformation of a thread and fibres Relationship between deformation of a thread and built-in fibres can be interpreted with thread kinetics and kinematics analysis in the stitch forming process and the influence of the thread twist on its deformations. The thread is moving on its way through guiding elements, tension regulator, take-up lever, sewing material and parts of bobbin in the stitch forming process. On the one hand, the thread is exposed to the force acting during passage through the sewing material but, on the other hand, it is exposed to the dynamic loadings. 2.1 Kinetics and kinematics of the sewing process Kinetics of the sewing process deals with the influence of the force acting on thread movement in the stitch forming process. Here, the moving part of a thread is exposed to different forces (GersÏak, 1986a,b): . friction of the bobbin thread on the place of interlace in the sewing material and continuous friction with guiding elements; . great tensile force; and . bending of the thread with small curvature radius. From the point of view of the stitch formation it can be seen that the thread is exposed to great tensile force when travelling with the sewing needle through the sewing material. Because of the small contact space in the area of the sewing needle eye, the thread is exposed to a great normal and moving pressure as well as to frictional forces and bending, which results in considerable thread destruction. The most frequent, characteristic deformation of the thread bending in interaction with the sewing needle is shown in Figure 1 (GersÏak, 1986b). Forming of the loop started after the phase of the stitch stretching, with the movement of the sewing needle with the thread against the sewing material. The friction forces act between the thread and sewing needle eye on the input part of the needle thread. At the same time the sewing thread is exposed to the bending loading (Figure 1a). In the beginning of the sewing needle penetration in the sewing material, the angle between the leaded part of the thread and the sewing needle eye is 90ë (Figure 1b). After the complete penetration of the sewing needle point through the sewing material, the needle eye with the thread goes inside the sewing
Figure 1. Thread bending in the area of the sewing needle eye
material. Because of the acting resistance of the sewing material, the thread gets additional bending; therefore the thread loop passes into the formed sewing needle groove. The bending angle of the thread increases in the left as well as in the right side of the needle eye and gets to approximately 180ë. That means that the thread parts (part in the stitch chained thread and part from the thread package flowing thread) enclose the upper edge of the needle eye and lie parallel to each other (Figure 1c). The thread is at this time also exposed to the thermal effect and friction between the sewing needle and sewing material. By lifting the sewing needle, a part of a thread in the long groove slides undisturbed, i.e. it is lifting up with the sewing needle. The friction force F1 acts on the thread in the short groove (GersÏak, 1986b): F1
1
2 F0
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291
1
F0 is the force, with which the sewing material presses on the sewing needle and thread, 1 is the friction coefficient between the thread and the sewing material, 2 is the friction coefficient between the thread and sewing needle. Friction coefficient 1 , that acts on the moving part of the thread over the sewing material, can be expressed in this form (GersÏak, 1986b): F1 1 2
2 F0 Since 1 is bigger than 2 , the thread moving on the side of the short groove has a retardant character, which results in the stitch formation. At the same time the take-up lever moves downwards and supplies the necessary length of the thread for stitch formation. The bobbin catches the loop and enlarges it with a part of the thread, which slides across the long groove of the needle. When the loop slides over the bobbin casing, the interlace with the bobbin thread is carried out. The take-up lever pulls up the needle thread, the loop reduces to such a size, that it moves close to the bobbin thread, with a slight touch or even without (Figure 2a) (GersÏak, 1986a,b). The first important touch of the needle thread with the bobbin thread begins at the moment of the entry of the needle thread in the hole of the needle plate. The needle thread pulls the bobbin thread from the left side of the needle plate hole, then bends and pulls it further over the resulted interspace inside the sewing material (Figure 2b). Both threads bend almost for 180ë, which means that they ply together. Loop movement, originated with interlace of the needle and bobbin thread, is opposite to the frictional force, which acts on the sewing material and individual parts of the bobbin (Figure 2c). Figure 2. Needle thread bending at reciprocal effect with the bobbin thread
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On the basis of the thread movement analyses in the stitch forming process it can be seen that the most problematic is thread bending in the sewing needle eye area and at the interlacing point of the needle and bobbin thread. Since the thread slides over the surface with a small curvature radius, great normal and movable pressure affects it, while the forces of the tangential resistance (frictional forces), which lie on the particular fibre surfaces in the thread, are present on relatively small contact surfaces. In the case of reduction in the curvature radius, it amounts to considerable increase of the tangential force resistance and to reduction of the contact surface of the fibres twisted in the thread when compared with the sewing needle, i.e. thread in the loop. Tangential resistance forces, which are present just on the one part of the fibre's surface in the thread, cause their overloading or even the thread's destruction (GersÏak, 1986a,b, 1987). On the basis of the sewing process kinematics thread loading during the stitch forming process indicates that dynamic loading of a thread sD, which is caused by compression force of the tension regulator's activity, force of the tension spring, friction forces and mass acceleration forces, is transmitted on the moving part of a thread between tension regulator and last formed stitch, i.e. on particular places between the fibres (GersÏak, 1986a, 1987, 1991, 1992a,b, 1994). The dynamic load of a thread causes with other loadings, such as bending, compression, friction, striking moment and thermal effect, the greatest or smallest thread deformations, which are exhibited in mechanical deformations of a thread or even in structural changes of a thread. Tensile force of the thread in the stitch stretching moment is defined on the basis of the tensile force, which acts on a thread in the stitch formation process from the thread package to the last formed stitch. Since the greatest tensile force in the thread occurs at the moment of stitch stretching, when the take-up lever pulls for the stitch forming the required thread length through the tension regulator, simultaneous with the movement of the sewing material, the dynamic tension of a thread can be expressed with tensile force at the moment of stitch stretching in the form (GersÏak, 1991): ! ! 7 7 X X FN 4 4 i i 1 exp i i R
e Fstr F exp 2 i1 i1 ! ! !
3 7 7 6 7 X X X X mi exp j j mi exp j j m7 a i1
j1
i1
j1
where: Fstr ± the force needed to draw off the thread from the bobbin, v cN FN ± the pressure that acts upon the thread in the area of the tension regulator, in cN a ± acceleration of the thread, in ms-2
mR ± the friction coefficient between the plates of the tension regulator mi ± i ± 1,2,. . .,7 ± the mass of the part of the thread in the area of slipping elements Mfri-1 and Mfri, in g Dmi ± i ± 1,2,. . .,7 ± the mass of the part of the thread in the area of slipping element Mfri, in g ai ± i ± 1,2,. . .,7 ± the encircling angle of Mfrith friction element, in rad aj ± j ± 1,2,. . .,7 ± the encircling angle of Mfrjth friction element, in rad mi ± i ± 1,2,. . .,7 ± the fiction coefficient in the area of the Mfrith friction element. From the gained Equation (3) it can be seen that the tensile force of the thread is a function of the number of thread transitions through the friction elements, type and quality of guiding elements, frictional properties of the thread, thread fineness, thread acceleration and force with which the tension regulator acts on the thread. Analysis of the stitch formation process and forces in action here shows that we are dealing with a complex process of the thread loading including bending and friction, effect of striking and bending moment, tensile movement of a thread and forces of the tangential resistance on the small contact area of the fibres in the thread. This leads to the local overloading of a fibre surface in the thread, which is reflected as changes in the mechanical properties of fibres twisted in the thread. 2.2 The influence of the twist on the thread deformation The thread takes the geometry of line formed fibres, which are connected with twisting over the cohesive forces and under a defined twist angle inclined with regard to the longitudinal thread axes (SÏavic and GersÏak, 1997). Analysis of the influence of yarn twist on its deformation indicates that, with twisting of the spun yarn, the tenacity and modulus increase to the defined critical number of twist. After this point, the strength starts to decrease because of the occurrence of slippage between the fibres. For filament yarns, twisting means a consolidation of the filaments and thus better appearance, abrasion, etc., while modulus and strength decrease with twist (Erich, 1969; Harch, 1993; NikolicÂ, 1997). With twisting, the fibres parallel with the yarn axes incline for a defined angle and twist around the yarn axes, which causes torsion moment that, owing to rotation of a great number of fibres around the yarn axes, actuates different elongations of fibres in the yarn. Fibres, which are closer to the yarn axis, have smaller elongation than fibres in the yarn coat (Sundaresan et al., 1997). Fibres from the coat cause compression forces on fibres towards the core. This leads to greatest adhesion between fibres in the yarn and therefore to appropriate yarn or thread strengthening (Figure 3). With excessive thread twisting it achieves even greater torsion moment and compressional forces on fibres towards the core, which causes critical loading of the thread structure, i.e. in the thread twisted fibres. This is reflected as deformation of a thread as well as in the thread twisted fibres.
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294 Figure 3. Influence of the torsion moment on elongation and compression of the fibres in yarn
2.3 Influence of a dynamic loading of the thread on alteration of the mechanical properties in the thread twisted fibres The mechanical behaviour of threads depends on the properties of constituent fibres and their arrangement. During tensile loading the tension induced by applied strain is transferred to the fibres through the interfacial shear stress, which depends on the transverse force on the thread and the property of the interface. Also the transverse force, developed through the radial compression of the thread, depends on the structural properties and the thread friction coefficient, interplay pressure between yarns twisted in the thread and thread twist. Interfacial shear stress depends on factors such as fibre friction and the geometry of the contact surface (Broughton et al., 1992). On the basis of this diescription any change in the tensile property of the thread can be attributed to the changes in: . property of the constituent fibres in the thread; . frictional properties between fibres; and/or . transverse force of the entire structure of the thread. Research into the effect of the interfibres friction on the yarn strength indicates that already small changes in the friction between the fibres can cause greater changes in the yarn strength, although friction is greatly influenced by factors such as twist, fibre dimension and the structure of the fibre surface (Morton and Hearle, 1993). The relationship between the deformation of a thread and fibres can be described with the mechanical description of tensile loading: thread tension is generated by applied strain, which is resisted by interfibre friction. As generated tension acts on the helical structure, the yarn is a compressed radial and a force normal to the fibre surface is produced. As the normal force between fibre surfaces in the yarn increases, the frictional force necessary to produce slippage increases and the tension generated by applied strain continues to increase. The increase in tension force is limited by the tensile strength of the fibres. When the generated tension exceeds the fibre strength, then thread damage will occur because of fibre damage (Morton and Hearle, 1993).
Also the behaviour of the thread on a constantly increasing load gives stress-deformation curve s(e) (GersÏak, 1997a). Stress-deformation curve shows that in the initial region of the steep angle of s(e), stress s increases proportionally with deformation e, which is given with the term: E0 "
The thread and built-in fibres
4
and corresponds to the elastic deformation. This is initially Young's module, which is equal to the slope at the beginning of the stress-deformation curve. When stress in this phase decreases, the deformation is totally reversible. When this confine is extended, stress is not proportional to the relative deformation any more. The curve changes and deformation increases faster with stress. The deformation which appears as a result is not totally elastic any more. It is plastic-elastic or visco-elastic. The point at which this change appears is the yield point (SÏaric and GersÏak, 1997; GersÏak, 1997b).
295
3. Experimental part Dynamic loading of the thread in the sewing process and the mechanical properties of differently twisted threads before and after the sewing process have been investigated regarding the study of the relationship between deformation of the thread and fibres. Thread, produced from 100 per cent PES fibres (PES filament core and PES coat) with the linear density of 13.5 tex 6 2, twisted with different twist numbers, was used. The basic properties of applied thread are listed in Table I. Research has been carried out on a fabric containing 100 per cent wool in a twill weave with surface mass of 196gm-2, warp density 26 yarns cm-1 and weft density 23 yarns cm-1. Samples were sewn with the seam type 1.01.01/301 at the stitch length 2.5mm and with three different stitching speeds: 2,000 stitch min1 , 3,000 stitch min-1 and 4,000 stitch min-1, with previous pre-tension of the thread, equal for all speeds, which has ensured the faultless seam. The needle thread was carefully taken out of the seam, from which the individual fibres have been extracted for measuring the mechanical properties. The measurements of the dynamic loading, i.e. the tensile force of the thread, were carried out on the sewing-machine Brother DB2 B737-913, with the help of a custom-built measuring device for measurement of the tensile force of the thread. The measurement results are given as average values of the Investigated parameters Nominal fineness Tt/tex Real fineness Tt/tex Nominal twist T/tm-1 Real twist T/tm-1 Breaking tension s/cNtex-1 Breaking elongation e/%
S2 13.562 30.43 800 779.68 35.886 18.985
Thread type S3 13.562 30.96 1,036 1,124.40 35.357 20.263
S4 13.562 31.52 1,200 1,334.72 34.193 19.990
Table I. Properties of the applied threads
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characteristic peaks of the tensile force and in the form of the graph of the thread's tensile force depending on the time. Fifty measurements of the maximal peaks, i.e. tensile forces at the moment of the stitch stretching, were evaluated for the individual stitching speed. The measurements of the mechanical properties were carried out on electronic feeding dynamometer type Vibrodyn 400, connected with the linear density measuring device Vibroskop 400. All measurements were carried out under standard testing conditions according to standard DIN 53 816 (GersÏak, 1997b). Using the requisite program the dynamometer records linear density, breaking force and breaking elongation. Then it automatically calculates the breaking tenacity, breaking extension and initial elasticity modulus at 1 per cent extension. 4. Results with discussion The measurement results of the tensile force of the thread at the moment of the stitch stretching indicates that with the stitching speed the tensile force of the thread increases, because with the increased stitching speed it achieves a greater tensile load and the movement of the thread is increasingly accelerated (Table II). The tensile force has the greatest value for the thread type S2, which has the Lowest twist. At the stitching speed of 2,000 stitch min-1 the tensile force is 1,226N, then it increases to 1,234N at 3,000 stitch min-1, while at the stitching speed of 4,000 stitch min-1 it amounts to 1,241N. For the thread types S3 and S4, which have higher twist, the tensile force in the thread is lower, which can be attributed to the lower friction forces of the thread. Higher thread twist decreases the friction surfaces of the fibres twisted in the thread; the result is smaller friction. The measurement results of the mechanical properties of the fibres in the thread before and after the sewing process, the fineness of the fibres, breaking tenacity, breaking extension and initial elasticity modulus are shown in Table III. The result indicates that different numbers of the thread turns influence the mechanical properties of the fibres twisted in the thread. Therefore, the fibre fineness increases with twisting from 3.41 dtex for thread type S2 with 800tm-1 to 3.48 dtex for thread type S4 with 1,200tm-1 (Figure 4). The breaking tenacity of the fibre decreases with twisting from 64.8 cNtex-1 for thread type S2 to 64 cNtex-1 for thread type S3 and it achieves the minimal value of 62 cNtex-1 for thread type S4 (Figure 5), while the breaking extension of the fibres with twisting increases (Figure 6). Like the breaking tension, also the
Table II. Results of measurement of the thread dynamic force depending on the stitching speed
Thread type Stitching speed n/st min-1 Average value x Standard deviation s Coefficient of variation V
Dynamic force F/N S3
S2 2,000 1.226 0.092 7.463
3,000 1.234 0.087 7.067
4.000 1.241 0.061 4.877
2,000 0.974 0.139 14.233
3,000 1.024 0.208 20.271
4,000 1.077 0.082 7.625
S4 2,000 3,000 4,000 1.058 1.067 1.073 0.145 0.200 0.082 13.748 18.716 7.656
Breaking tenacity Breaking Initial elasticity Stitching Fineness Fb extension eb modulus (1%) E0 Thread speed Tt type n/stitch min-1 dtex s V cNtex-1 s V % s V cNtex-1 s V S2a S2SÏ2000 S2SÏ3000 S2SÏ4000 S3a S3SÏ2000 S3SÏ3000 S3SÏ4000 S4a S4SÏ2000 S4SÏ3000 S4SÏ4000
/ 2,000 3,000 4,000 / 2,000 3,000 4,000 / 2,000 3,000 4,000
3.41 3.36 3.36 3.31 3.41 3.37 3.38 3.36 3.48 3.45 3.45 3.40
0.11 0.11 0.10 0.10 0.11 0.10 0.08 0.08 0.13 0.11 0.12 0.12
3.3 3.4 2.8 3.0 3.3 3.0 2.5 2.5 3.6 3.3 3.5 3.5
64.8 64.1 65.2 64.5 64.0 64.8 64.0 63.8 62.0 62.3 62.2 62.8
2.4 2.5 1.6 2.2 2.0 2.4 2.2 2.1 2.3 2.3 2.3 2.3
3.8 4.0 2.5 3.3 3.2 3.7 3.4 3.3 3.7 3.7 3.6 3.7
20.6 19.4 18.8 18.1 21.5 21.2 19.1 18.7 22.3 21.0 20.8 19.4
1.6 1.9 1.3 1.6 1.5 1.7 1.6 1.5 1.6 1.5 1.9 1.5
7.7 9.6 6.9 8.8 7.0 8.1 8.5 8.0 7.1 7.2 9.0 7.5
122 212 198 307 84 140 118 136 76 85 91 113
24 58 41 87 11 25 12 20 8 9 10 21
19.6 27.4 20.6 28.4 13.2 18.2 10.0 14.4 10.5 10.6 11.0 18.2
Note: asewing thread before sewing
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297 Table III. Results of measurement of the mechanical properties of the fibres in the thread before and after the sewing process
initial elasticity modulus decreases with twisting (Figure 7). This means that a higher number of the thread twist reduces its resistance to extension. So the initial elasticity modulus of the fibres amounts for thread type S2 to 122 cNtex-1, for thread type S3 to 84 cNtex-1 and to only 76 cNtex-1 for thread type S4. The analysed results of the influence of the sewing speed on mechanical properties of the fibres indicates (Table III), that with increasing stitching speed the fineness of the fibres decreases for all threads (Figure 8). Lower fineness of the fibres is reflected with increased tensile loading, short strike forces, friction and rubbing because of the increase in the stitching speed, which is shown also in changes in other mechanical properties. The measurement results of the breaking tenacity of the fibres in relation to the stitching speed do not show fundamental changes (Figure 9), while the breaking extension decreases with increased stitching speed (Figure 10). The decrease in the breaking extension of the fibres with higher thread twist is bigger and it decreases in relation to the thread before and after sewing; with a stitching speed of 4,000 stitch min-1, for thread type S2 it is 2.5 per cent, for thread type S3 2.8 per cent and for thread type S4 2.9 per cent. Results of the initial elasticity modulus indicate the dependence of the increase of the
Figure 4. Influence of thread twist on fineness of the fibres
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Figure 5. Influence of thread twist on breaking tenacity of the fibres
Figure 6. Influence of thread twist on breaking extension of the fibres
Figure 7. Influence of thread twist on initial elasticity modulus of the fibres
Figure 8. Influence of the stitching speed on fineness of the fibres in the thread
modulus on the stitching speed (Figure 11), which is greatest for thread type S2 and is before sewing 122 cNtex-1, after sewing at the stitching speed of 2,000 stitch min-1 212 cNtex-1, at 3,000 stitch min-1 198 cNtex-1 and 307 cNtex-1 after sewing at the stitching speed of 4,000 stitch min-1. This means that on the basis
of the technologically conditioned forces, which have been acting on the thread, the fibres' elastic ability after the sewing has been decreased, which can with additional loadings of the thread in the finished seam lead to the decomposition of the thread structure. On the basis of the study of the kinetics and kinematics of the sewing process, as well as regarding the thread twist, measurement results of the tensile forces in the thread and mechanical properties of the fibres in the thread before and after the sewing process, it was found that the deformation of the fibres in the thread occurred, which was the result of the acting tensile and friction forces, on the one hand, and short strike loadings and tensile loading of the thread, on the other.
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Figure 9. Influence of the stitching speed on breaking tenacity of the fibres
Figure 10. Influence of stitching speed on breaking extension of the fibres in the thread
Figure 11. Influence of stitching speed on initial elasticity modulus of the fibres in the thread
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5. Concusion The analysis of the results of the research regarding the relationship between loading of the thread and deformation of the fibres shows that because of the thread loadings in the sewing process, which are caused by the technologically conditioned forces in the sewing process, there occur structural changes in the thread. This results in changes in the mechanical properties of the fibres twisted in the thread after the sewing process, i.e. change in the fineness, breaking tenacity, breaking extension and initial elasticity modulus of the fibres in the thread. References Broughton, R.M. Jr, El Mogahazy, Y. and Hall, D.M. (1992), ``Mechanism of yarn failure'', Textile Research Journal, Vol. 3 No. 62, pp. 131-4. Eirich, F.R. (1969), ``Rheology, theory and applications'', The Geometry of Tensional Behavior of Yarns, Polytechnic Institute of Brooklyn, Brooklyn, New York, NY, pp. 493-9. GersÏak, J. (1986a), ``Obremenitve sukanca med procesom sÏivanja na hitrih sÏivanih strojih'', Tekstilec, Vol. 29 No. 7-8, pp. 253-6. GersÏak, J. (1986b), ``Deformacije sukanca v procesu oblikovanja vboda'', Tekstil, Vol. 35 No. 7, pp. 477-89. GersÏak, J. (1987), ``Analiza obremenitev sukanca med procesom oblikovanja vboda'', Tekstil, Vol. 36 No. 9, pp. 481-9. GersÏak, J. (1991), ``DinamicÏko naprezanje konca kao posljedica tehnolosÏki uvjetovanih sila u procesu oblikovanja uboda'', Tekstil, Vol. 40 No. 5, pp. 213-22. GersÏak, J. (1992a), ``TehnicÏko ± tehnolosÏki parametri konca i njihov utjecaj na cÏvrstocÂu odjevnih sÏavova'', Tekstil, Vol. 41 No. 5, pp. 211-18. GersÏak, J. (1992b), ``Vpliv tehnicÏno-tehnolosÏkih parametrov sÏivanja na kakovost sÏivov'', Simpozij OblacÏilno inzÏenirstvo 1992, Faculty of Mechanical Sciences, Maribor ± ITKP, Ljubljana, pp. 49-63. GersÏak, J. (1994), ``Vpliv reolosÏkih lastnosti sukancev na njihove dinamicÏne obremenitve v procesu oblikovanja vboda, I'', International Conference IMCEP '94, Faculty of Mechanical Sciences, ITKP, Maribor, pp. 88-95. GersÏak, J. (1997a), ``SÏtudij meje prozÏnosti sukanca, II.'', International Conference IMCEP'97, Faculty of Mechanical Engineering, Institute of Textile and Garment Manufacture Processes, Maribor, pp. 262-8. GersÏak, J. (1997b), DIN 53 816, ``Einfach Zugversuch an einzelnen Fasern'', pp. 105-16. Hatch, K. (1993), Textile Science, Yarn Construction, University of Arizona Tucson, West Publishing Company, St Paul, MN, pp. 287-99. Morton, W.E. and Hearle, J.W.S. (1993), Physical Properties of Textile Fibres, Tensile Properties, 3rd ed., The Textile Institute, Manchester, pp. 265-305. Nikolic M. (1997), ``Teorija in tehnologija predenja'', Faculty of Natural Sciences, Department of Textiles, University of Ljubljana, Ljubljana, pp. 32-7. ÏSaric A. and GersÏak J. (1997), ``Vpliv vitja na elasticÏne lastnosti sukanca, II.'', International Conference IMCEP'97, Faculty of Mechanical Engineering, Institute of Textile and Garment Manufacture Processes, Maribor, pp. 315-19. Sundaresan, G., Hari, P.K. and Salhotra, K.R. (1997), ``Strength reduction of sewing threads during high speed sewing in an industrial lockstitch machine: Part I: Mechanism of thread strength reduction'', International Journal of Clothing Science and Technology, Vol. 9 No. 5, pp. 334-45.
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New shielding protective equipment for live working
Protective equipment
Claudia Herzberg and Hartmut RoÈdel
Institute of Textile and Clothing Technology, Technische UniversitaÈt Dresden, Germany and
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Eberhard Engelmann
Institute of High Voltage and High Current Engineering, Technische UniversitaÈt Dresden, Germany Keywords Protective clothing, Shielding Abstract The new protective equipment forms a FARADAY cage, thus protecting the worker from unacceptably strong electrical fields as well as from being invaded by dangerous electric currents. The protective shielding clothing described is a personal protective equipment of the highest category. Therefore, it must be certified by an acknowledged examining and certifying authority. An application with regard to the attestation of conformity for this protective clothing has been submitted to the Examination and Certification Section of the Expert Committee for Electrical Engineering.
1. Introduction Live working in high-voltage networks with nominal voltages of up to 110kV is as a rule bare-hand working, i.e. one or more workers are in direct contact with the live plant devices. For this purpose, insulating ladders, lifting platforms or helicopters are used to bring the worker directly on to such parts as conductor cables, bus bars or fittings that are on a very high electric potential. An equipotential bonding device provides an electrically conducting coupling between the workers and the live parts. The field strength intensity around such parts can reach some 100kV/cm. As a result, an inadmissibly high current of some mA would invade unprotected people working at high-voltage potentials. For this reason a shielding protective suit in the sense of a Faraday cage is necessary for bare-hand working at high-voltage plants. 2. Requirements made on shielding protective clothing for alternating voltages up to 800kV 2.1 Shielding effect The main requirement made on live working protective clothing for work at high-voltage plants is a sufficient shielding effect from the intense electrical fields of the power line frequency. The shielding effect should be at least such that the density of the current that is induced by the electrical field in the human body will not exceed 10mA/m2 (Bundesamt f.S., 1995). No dangerous biological effects can be observed below this limit, which has also been recommended by the World Health Organization (WHO).
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A current of about 10mA would invade an unprotected worker during live working at a 765kV transmission line. If we assume an effective body surface of 1m2 as well as a homogeneous current distribution, the current density will not exceed 10mA/m2. Since in practice the current distribution is always inhomogeneous, however, and the current density as a result assumes higher values in some places, the body current should not exceed 100mA. As a consequence, the shielding attenuation of the worker's protective clothing should be at least 40dB. This value is also in accordance with the requirements made for shielding live working protective clothing by the IEC 60895 (IEC, n.d.). Closed metal screens ensure this shielding attenuation without difficulties. If the latter is to be obtained by shielding textile materials, this implies high demands which are made on their electrical conductivity. Therefore, material samples have to be tested to show whether a shielding textile material is suitable. 2.2 Current-carrying capability In addition to the fact that the shielding protective clothing of a live worker changes the electrical field in the high-voltage plant, it also causes local field intensities in the clothing after coupling to the high-voltage potential, which causes partial discharges to ignite. These discharges carry currents up to 100mA, which have to be borne by the conductive textile material, at the same time preventing the shielding material from becoming unacceptably warm due to current heat loss. For this reason, a special current-carrying capability test is carried out to prove that the shielding material will not ingnite if a test-current of 1A flows through the material. 2.3 Inflammation protection The thermal energy occurring with electric discharges may be local such that the textile material may get ignited. Since this must not happen to workers in shielding protective clothing during live working at high-voltage plants under only circumstances, the material must show sufficient stability against ignition. Therefore, the textile fabric has to be designed such that ignition is suppressed or that the flames expire quickly, respectively. These properties have to be considered in advance when the material is chosen and they have to be proved by testing, too. 2.4 Weather protection Protective clothing for live working must protect the wearer from heat, cold and wind, in general. Decisive factors are the air temperature, the thermal radiation (sun and sky radiation), humidity and the air speed (Din, 1988). The design of the protective clothing must therefore be in accordance with the climatic influences to be expected. Its physiological comfort is determined by a complex of heat transfer properties and moisture-carrying qualities (Din, 1994). Since live working is currently not conducted when it is raining, the protective clothing need not be waterproof. This makes the construction of the clothing easier.
2.5 Mechanical demands during wearing A textile fabric designed for protective clothing for live working must take up the specific mechanical loads occurring when it is worn. The assessment of the mechanical strength of the material and the seams considers such issues as tensile strength, resistance to tear propagation, seam strength and abrasion resistance. These parameters are of particular importance for the outer layer of the protective clothing. 2.6 Ergonomics In addition to the demands mentioned earlier, the ergonomic design of shielding protective clothing for live working deserves particular attention. Despite its protective function the shielding clothing is expected to provide the bearer with the best practical wearing comfort. As a result, the fabric of the suit must demonstrate a small mass per unit area. Furthermore, it is essential that the clothing is put on easily and that it maintains its fit during all types of movements (DIN, 1993). This is true not only for the suit, but also for the protective helmet, the visor, and the shielding gloves and socks. Visibility must not be limited by the protective helmet and/or the special hood and also the visor. The visor must not show condensation as a result of breathing. Moreover, the wearer of a protective helmet and/or hood must be able to perceive acoustic signals. Dimensional alterations (shrinkage or extension) of the clothing, which may occur as a result of cleaning, have to be reduced to a minimum to allow the user to move freely. 2.7 Aging Particular demands are made on the aging resistance of the shielding textile materials. On the one hand, aging depends on the material properties and also on numerous external influencing factors. Aging during storage or the usual use is normally a slowly progressing process. In addition to this, aging may be accelerated, if the protective clothing is subjected to intense sweat during wearing. The greatest danger from sweat is that it contributes to the corrosion of the conductive layer and thus it reduces the shielding effect. Therefore, the suit should be regularly cleaned (washing or dry cleaning is recommended). 3. A new shielding protective clothing 3.1 Design of the protective clothing The new protective clothing consists (Plate 1) of a suit with a special hood, shielding gloves and socks as well as various protective helmets. The suit, gloves and socks are made of three layers. The outer suit layer is a flame-retardant, tear-resistant fabric. The medium layer is a material that is a consistently metallised polyamide fabric. It is finished with copper and/or silver and demonstrates an excellent shielding effect against electric fields. The inside layer facing the body is made of a cotton knitwear absorbing body liquids.
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Plate 1. Measuring of shield attenuation of the new protective equipment
A particular advantage of the new protective clothing is the fact that hands and feet are completely covered by shielding material. In contrast to the suit, the outer layer of the gloves is made of flame-retardant leather and that of the socks is made of a soft cotton knitwear. The inner layers are identical to those of the suit. The feet are completely protected by shielding socks, which show the same structure as the suit. They are joined to the suit by metallised zip-fasteners with the electrical conductivity being ensured. In this case the worker can be provided with socks of the appropriate size and the socks can be cleaned or replaced in case of wear-out, even if the suit itself is still fully functional.
Normal shoes that are in accordance with the industrial safety regulations may be put over the socks. No special live-working requirements are made on them. The hood attached to the suit may protect the head from strong electrical fields. A plastic helmet may be worn under this hood in case of small field strength, e.g. for working near live plants or parts of them or for working at plants with nominal voltages up to 420kV. For working in strong electric fields, e.g. at plants up to 800kV, a helmet has been developed with a metallised helmet shell and a conductive visor to protect the face. The gloves, the shielding protective helmet and the equipotential bonding device are connected to the suit by special safety plug-in connectors that secure conductivity. These connectors make it possible to detach the accessories easily without tools, to replace them or to adjust them to specific working conditions. The protective suit as well as the socks are highly permeable to water vapour and extremely porous. Thanks to their pattern construction they are extremely comfortable to wear. The protective suit has been developed in five standard sizes to fit various body heights. The current-carrying capability and shielding effect of the entire suit may only be obtained to the required extent if the unavoidable seams are also highly electrically conductive. For this reason the seam has to be constructed such that the metallised layers of the fabric join neatly. 3.2 Shielding effect of the complete protective clothing The material choice, which has been made after extensive material tests, together with the design of the protective clothing described earlier in this paper, guarantees a high shielding effect, satisfying safety and other standards. The shielding effect has to be proved for maximum phase-to-earth voltage in a type test in accordance with IEC 60895 (n.d.) and/or DIN EN 60895 (DIN, 1998), respectively, for which the protective clothing is specified. The shielding effect of the protective clothing is quantified with the shielding measure S: I1 S 20 log I2 where: I1 ± is the overall current which flows over the shielding protective clothing largely as a capacitive displacement current; and I2 ± is the body current which flows through the body of the persons to be protected because of the limited shielding effect of the protective clothing.
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The protective clothing presented fulfils the requirements made on the shielding effect very well. Depending on the chosen head protection (isolating helmet with hood or shielding helmet with or without shielding visor), shielding measures of up to 48dB may be obtained. Since a specially equipped high-voltage laboratory is needed to determine the shielding measure, we recommend a regular measurement of the specific insulation resistance of the protective clothing as an alternative to the equipment's shielding effect. This is, moreover, a suitable method to monitor the ageing of the protective clothing starting from the initial new state or to detect damages in the shielding layer. The plug-in connectors, additional measuring points and also a special pair of tongs for the measurement of gloves and socks are designed to measure this resistance. The shielding effect of the protective clothing is no longer sufficient, if the electrical resistance between selected points of the clothing is greater than 60O. 3.3 Wearing and cleaning Perspiration, which is an inevitable result of the physically hard live working and the sometimes extreme weather conditions, is a stress factor for protective clothing, in particular for the shielding layer of the fabric, which should not be underestimated. The perspiration partially soaks the suit and makes it age more quickly. Scanning electron microscope photographs (Figure 1) and energydispersive analysis show that residues of sweat and environmental dirt are found on the metallised yarns and in particular between the yarns of the
Figure 1. Scanning electron microscope photograph of the metallised fabric of an extremely dirty suit (magnification 6 3,000)
shielding fabric. These residues have a negative effect on the electrical conductivity, the current-carrying capability and the shielding effect of the fabric. To remove the sweat residues and the dirt the fabric must be cleaned. The suit may principally be washed or dry cleaned. Since any cleaning process means additional stress and ageing, specific tests have been made on fabric samples to find the most favourable procedure. In particular, it has been tested whether the electrical properties have been changed excessively after the ten washing or dry-cleaning cycles demanded by IEC 60895 (n.d.). During washing and dry cleaning the fabric is subjected to the washing and dry cleaning chemicals, on the one hand, and to mechanical stress on the other. As scanning electron microscope photographs show (Figure 2), cracks may occur in the conductive layer as a result of cleaning abuse, which affect the electrical resistance (Figure 3), the current-carrying capability and the shielding effect. Since the electrical properties of the shielding fabric remain practically unaltered during dry cleaning, it is recommended that one should dry-clean the protective clothing when necessary.
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4. Certification The protective shielding clothing described in this paper is a personal piece of protective equipment of the highest category. Therefore, it must be certified by an acknowledged examining and certifying authority. An application with regard to the attestation of conformity for this protective clothing has been submitted to the Examination and Certification Section of the Expert Committee for Electrical Engineering.
Figure 2. Scanning electron microscope photograph of a silver fabric after washing malpractice (magnification 6 10,000)
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Figure 3. Effect of dry cleaning cycles on the electric resistance of a silver fabric References Bundesamt fuÈr Strahlenschutz (1995), Empfehlung der Strahlenschutzkommission ± Schutz vor niederfrequenten elektrischen und magnetischen Feldern der Energieversorgung und -anwendung. DIN EN 33 403 Teil 3 (1988), ``Klima am Arbeitsplatz und in der Arbeitsumgebung, Beurteilung des Klimas im ErtraÈglichkeitsbereich''. DIN EN 340 (1993), ``Schutzkleidung. Allgemeine Forderungen''. DIN EN 31 092 (1994), ``Textilien, Physiologische Wirkungen, Messung des WaÈrme- und Wasserdampfwiderstandes unter stationaÈren Bedingungen''. DIN EN 60895, DIN EN 60895 (VDE 0682 Teil 304) (1998), ``Schirmende Kleidung zum Arbeiten an unter Spannung stehenden Teilen fuÈr eine Nennspannung bis AC 800kV'', February. IEC 60895, ``Conductive clothing for live working at a nominal voltage up to 800kV ac. or 400kV d.c.''
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IJCST 13,5
Optimal combinations of face and fusible interlining fabrics Sang-Song Lai
322 Received March 2000 Revised March 2001 Accepted March 2001
International Journal of Clothing Science and Technology, Vol. 13 No. 5, 2001, pp. 322-338. # MCB University Press, 0955-6222
National Pintung University of Science and Technology, Taiwan, Republic of China Keywords Composite materials, Quality, Artificial neural networks Abstract Garments are now becoming high class and automated. Using key face fabrics and interlining structure properties to predict the quality grade of fused composites has become an important subject in the pursuit of quick reaction of fabrics. The establishment of the ideal composite parameters for interlining and face fabrics allows us to know the ideal interlining for face fabrics sooner. Hence, this paper, through discriminate analysis and the scatter plot, successfully found the ideal composite condition range for interlining and face fabrics. Artificial neural network training was used for the structural prediction of a fused composites quality model. Model tests showed the presence of good prediction ability.
Introduction In view of the development of rapid reaction system for garments, shortage of garments experts, and the demand for diversified low-volume production, highquality garment trends veer towards the prediction of garment quality and establishment of automated engineering management technology through key parameters (Lai, 1995; Potluri et al., 1996). Interlining fusing technique plays a very important role in the production of high-class garments, especially in the production of men's suits where it takes up more than 60 percent of the suit. Interlining is the internal part of a suit, although it is not visible, but the fusion of interlining and face fabrics affects the style, sewing, handle comfort and fusing durability of the suit. This increases the importance of the matching and combination suitability of the interlining and the suit face fabrics. In the past, garments factories mostly relied on experience when combining interlining and face fabrics. Fashion designers often conducted a number of interlining and face fabrics fusing experiments, then picked the interlining most suited for the face fabric. This process is very subjective and lacks efficiency. It seriously violates all the modern trends in garment development. Hence, in other correlating studies, researchers used the mechanical properties determined through the fabric assurance by simple testing (FAST) system. They were able to successfully establish models for predicting the handle and drape of fused composites (Fan et al., 1997a, b, c). Then through the KES-FB (Kawabate Evaluation System for Fabrics) system, they determined the best interlining and suit parts (collar, front lapel, sleeve, pocket, etc.) combinations (Lin et al., 1997). However researchers overlooked the effects of the fundamental interlining and face fabrics' structural properties on fusing quality and, thus, were not able to establish a predictor model for the fusing quality. As a result, fashion designers are unable to determine the ideal combination based on face fabrics and interlining properties. Therefore, this paper focused research on the interlining properties to understand
the suitable combination for the winter suit materials for men. First, analysis of variance was applied to the structural properties of a number of face fabrics and interlining to understand the parameters that can significantly affect fused composite qualities. Then, discriminate analysis and the scatter plot were used to find out the scope of fusing quality parameters. Finally, artificial neural network training was applied to the structural properties of face fabrics and interlining to predict the quality grades of fused composites.
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Experiment method Material properties and fusing conditions Procedure for selecting the research samples: 180 prevalent fabrics that are suitable for making winter jackets are selected by textile experts from the market and used as the primary samples. Sixty-five fabrics are then randomly selected from the 180 fabrics as the experiment samples (60 fabrics for training and five fabrics for model testing). Although the number of samples may be small, each of the samples is representative and effective. Cellulose and microfiber weave fabrics were used for the face fabric research, and polyester/cotton 65/35 weave fabrics were used in the interlining research. The resin used was polyamide. Interlining was manufactured through powder scatter coating; properties are shown in Table I. A Bou-yeu D5-600 roller fuser was used for fusing, to understand the fusing conditions of interlining and face fabrics. Conditions were: . temperature, 1008C, 1308C, and 1508C; . time, 10sec, 15sec and 20sec; . pressure, 1kg/cm2, 1.5kg/cm2, and 2kg/cm2. Measurement of the fused composite quality grade Fused composite measurement includes strike-back area of resins, peeling strength, and total handle value (THV). Strike-back area of resins refers to the Parameter Face fabrics THV Cloth cover Thinness (mm) Twist factor Interlining THV Cloth cover Thinness (mm) Twist factor Resin amount (g/cm2) Resin size () Fusing Time (sec) Temperature (8C) Pressure (kg/cm2)
Maximum Minimum 4.20 24.0 0.91 5.20 2.60 31.3 0.35 4.00 50.0 100 20 15 2
1.40 11.0 0.18 1.40 1.10 11.0 0.10 1.20 25 25 10 100 1
Mean
Standard deviation
Variance
2.55 17.03 0.45 3.72 1.98 18.93 0.23 2.68 37.33 57.70 15 126.67 1.5
0.80 4.73 0.23 1.14 0.37 5.52 0.08 0.66 9.89 30.98 4.12 20.72 0.41
0.62 22.35 0.05 1.31 0.13 30.43 0.1 0.44 97.85 959.75 16.95 429.38 0.17
Table I. Details of samples
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area of the face fabrics penetrated by a 20 20cm fused composite resin. Peeling strength tests are effected through the JAMES-HEALE ALPHTEN-400 strength tester. According to the JIS L1086 principle, tests were conducted using the constant rate of loading. Total handle value was measured through the KN-301-W-JACKET formula. In 1975, Japan researched and developed an objective evaluation device for fabric handle. First, the Japanese textile industry organized the Hand Evaluation and Standardization Committee or HESC for short. Prof. Kawabata used the KES system to test the 16 mechanical properties of fabrics; including parameters such as tensile, shearing, bending, surface, weight, and thinness. Then, the fabric mechanical properties and the subjective hand value obtained by the Japanese hand evaluation experts were placed under statistics to predict the total hand value of fabrics. The successful experiment on the KES-FB system in Japan also gained the wide acceptance of fabrics industries in different parts of the world. It became a tool in fabrics marketing. It also sufficiently eradicated handle evaluation disputes of trading nations and became the global fabric handle language. Japan KES used the final usage of different fabrics to set up nine different fabric total hand value measurement formula. Therefore, the KES-FB system was used as a tool for hand textural evaluation in this research paper. As the application of research samples is for winter jackets, KN-301-W-JACKET formula was selected for THV evaluation. To measure the fused composite quality, this paper used the variance computation function of the SPSS software to separately identify the strike-back area of resin, peeling strength, and total handle value grades. There were five quality grades: grade 5 stands for best quality and grade 1 stands for the worst quality. The three types (strike-back of resins, peeling strength and THV of fused composite) of quality grades of each sample were averaged. Finally, the average numbers are given grades. Resin strike-back is a fused composite shortcoming that could not be tolerated; hence, in the end, resin strike-back samples were found. Quality grade is one grade lower. If the strike-back area exceeds 5cm2, then quality grade should not exceed grade 3. As provided in the aforementioned two principles, total quality grades are determined by fused composites. Moreover, peeling strength of fused composites should be more than 3kg/cm2 and total hand value should be higher than grade 3 for fused composite quality to reach grade 4. Best conditions of interlining and face fabrics The artificial neural network is often applied in automatic control systems to solve the prediction and classification problems, especially in the prediction of the powerful fault tolerance and strain capacity on nonlinear structural systems. Nowadays, artificial neural network has been developed into a rather mature technology and, especially aided by computer technology, has become a very convenient application technology. The strong promotion of ICNN Association in the field of academic research has made artificial neural network grow fast. It is now being widely applied in various fields, including science, engineering, agriculture, medicine, business, social science and humane studies. Also, many
researchers used artificial neural network technology to solve nonlinear problems in the fields of textile and apparel. Although it can be effectively solved by conventional statistical techniques, along with the continuous development of artificial neural network technology, artificial neural network in fact has turned out to have better prediction ability than the conventional regression method in some certain application aspects (Lai, 1999, 2000). In an attempt to understand the effect of face fabric and interlining structural properties on fused composite quality grade, this paper used the analysis of variance to conduct influence significance tests. Henceforth, structural properties with significant influence are placed under the scatter plot and discriminate analyses to determine the best interlining and face fabric combination conditions. The combination pattern of face fabrics, interlining structural properties and fusing conditions is the primary factor affecting fused composite quality. Hence, this paper, through the help of artificial neural network training in the hope of establishing a model for predicting the fused composite quality grades through face fabrics, interlining structural properties and fusing conditions. This paper used the back-propagation network having a total of three layers; namely the input layer, the output layer and the hidden layer. Structure is shown in Figure 1. Here the 13 structure properties were regarded as the input values of the network, while the fused composite quality grades was regarded as the output value of the network. The entire computation procedure, as far as we are concerned, is hidden. The training process of the artificial neural network is shown in the following sub-section). The training network. The nonlinear transfer function used the sigmoid function f (x) = 1/(1 + exp (±x)). The function value is between (0,1). Network parameter settings are shown in Table II. The computation of the weight changes between the hidden and output layers use the generalized delta rule learning. Network learning aims to reduce the delta between the target value and the prediction value. The learning quality is expressed by the energy
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Figure 1. Adopted neural network structure
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Table II. Parameters of artificial neural network
Term
Parameter
Learn rule Transfer function Number of input unit Number of hidden unit Number of output unit Number of train examples Number of test examples Number of train cycles Momentum factor Learn coefficient ratio F'offsot Hidden learn coefficient Output Lcoern coefficient
Belta-rule Sigmoid 13 5 1 160 160 10,000-12,000 0.40 0.50 0.10 0.30 0.15
function. This paper employed the gradient steepest descent method to reduce energy function to the minimum. Due to that the artificial neural network training and ratiocination processes are carried out in a ``black box'', selection of model variables and control of network training processes become rather difficult. Therefore, this study applied variable analysis (as shown in Table III) and related analyses of statistics in the selection of variables that may affect fused composites quality. As it is impossible to control the network training processes, various network parameters (as shown in Table II) were applied in repeated tests. Finally, EMS and model having the smallest residual were selected as the best models. As far as this paper is concerned, using the conditions provided in Table II for network training could obtain the best converged data.
Parameter
Table III. Analysis of variance
Face fabrics THV Cloth cover Thinness Twist factor Interlining THV Cloth cover Thinness (mm) Twist factor Resin amount (g/cm2) Resin size () Fusing Time (sec) Temperature (8C) Pressure (kg/cm2)
Strike-back of resins 1.743 2.293** 1.866 1.910* 1.301 2.386*** 1.558 2.044* 3.816*** 4.597*** 3.314*** 2.666*** 3.314***
Notes: * p < 0.05; ** p < 0.01; *** p < 0.001
F-value Peeling strength THV 1.714 1.071 1.000 1.748 1.782 1.753 2.360** 1.481 2.804*** 2.068** 2.066** 2.204** 2.066**
4.052*** 2.497*** 1.975* 0.956 2.181* 4.025*** 3.162*** 0.600 1.991* 1.786* 1.580 1.665 1.580
Total quality 2.825*** 2.794*** 2.957*** 3.368*** 3.098*** 3.010*** 4.409*** 4.544*** 4.070*** 1.995* 1.741 1.711 1.741
The equation for the energy function is: X
Tj E 1=2
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Yj2
j
where: E = energy function; Tj = target fused composite quality grades of the output layer; and Yj = predicted fused composite quality grades of the output layer. The steps required for a training network are: (1) Set network parameters. (2) Use the random method to set weight matrix W-xh and W-hy, as well as the bias value vector B-h and B-y initial values. (3) Input a training sample input vector X and the target output vector T. (4) Compute the predicted output vector Y. . Compute the hidden layer output vector H: net h
13 X
W
xhih Xi
B
hh ;
i
Hh f
net h .
1 1 exp
neth
:
Compute the predicted output vector Y: net j
5 X
W
hyhj hh
B
yj ;
h
Y j f
netj
1 1 exp
netj
:
(5) Compute the delta value : . Compute the output layer delta value : j Y j
1 .
Y j
T j
Y j :
Compute the hidden layer delta value : h Hh
1
Hh
5 X j
W
hyh j:
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(6) Compute the weight matrix revision W and the bias value vector revision B: . Compute the output layer weight matrix revision W-hy and the bias value vector revision B-y: W hyhj j Hh ;
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B yj j: .
Compute the hidden layer weight matrix revision W-xh and the bias value vector revision B-h: W xhih h Xi ; B hh h
(7) Change weight matrix W and bias value vector B-y: . Change the output layer weight matrix W-hy and the bias value vector B-y: W hyhj W hyhj W hyhj ; B yj B yj B yj: .
Change the hidden layer weight matrix W-xh and the bias value vector B-h: W xhih W xhih W xhih B hh B hh B hh
(8) Repeat steps (1) to (8) until converged (no apparent changes are noted in error) is achieved. . Network learning result measurement. The result measurement of the supervised learning network learning process is often measured by the error mean square and the right sorting rate. This paper aims to establish the predicted model network since the output value Y and the target output value T of its output layer processing element are real numbers. The converged degree may be measured by the error mean square. The formula is: s X 2 EMS
Tj YJ =Nout j
where: EMS: error mean square; Nout: processing element quantity of the output layer; Tj: The j target output value of the P example; and Yj: The j predicted output value of the output element of the P example. The range of the RMS value is between 0 and 1.0. If the converged value is less than 0.1, then it may be regarded as a good converged performance. In other words, network learning results are good. Model tests Model tests used three sets of new face fabrics and interlining, each possessing different quality grade to test the suitability of the ideal conditions stated in this paper, as well as the prediction ability of the fused composite quality grade model formed from the artificial neural network. A total of five model test samples, whose details are shown in Table I of this study, were randomly selected in the market from fabrics and lining suitable for making jackets. They are in fact new samples that have never been involved in the training of an artificial neural network model. Results and discussion Factors affecting the quality grades of fused composites This section delves into the face fabric and interlining structural properties, as well as the effects of fusing conditions on the fused composites quality. As shown in Table III, in terms of strike-back of resins, except for the face fabrics handle, interlining handle and interlining thinness (no significant influence on fused composites was noted), a significant level of influence was noted from all other parameters. The melt adhesive interlining is mainly attached to the face fabric structure by the resin that penetrates. During the resin transfer process, temperature, time and pressure are the key factors determining the fused composite quality. If temperature were too high, then resin would melt more than necessary and spread randomly over the face fabrics. It may even spread into the internal structure of the face fabrics and cause a strike-back effect. This condition will be aggravated further under high pressure and longer time exposure conditions. Hence, under a fixed resin proportion, the resin layer between the face fabrics and interlining would become thinner, thereby affecting the fusing strength. Moreover, since the internal constitution of the face fabrics is full of resin, fibers tend to stick together forming a closelink structure, a condition that affects the fused composite handle. This increases the importance of the face fabric and interlining structure properties. Related analysis revealed that strike-back area of fused composite tends to be negatively correlated to cloth cover of face fabrics, cloth cover of interlining and thinness of face fabrics, so when the cloth cover of interlining and face fabrics is small, the sparsity of the fabric structural will
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allow resin to easily penetrate the face fabrics. This condition is even more significant when thin face fabrics are used. However, the strike-back area of fused composites tends to be positively correlated to twist factor of face fabrics, twist factor of interlining, resin weight and resin size positive correlation. When the ends and picks yarns of the face fabrics and interlining have a high yarn twist factor, the fibers in the yarn will be closely cohered, making it difficult for resin to permeate between fibers. As a result, resin directly flows to the fabric surface. This condition is even more evident under coarse resin size and massive resin amount. In terms of peeling strength, there are six parameters causing significant influence; such as resin size, resin amount, interlining thinness, temperature, time and pressure. The peeling strength of fused composites tends to be negatively correlated to twist factor of face fabric and twist factor of interlining. So under high yarn twist factor conditions, the resin would undergo a strike-back effect and fail to permeate into the yarn structure. As a result, the resin between the interlining and face fabric becomes sparse, reducing the adhesion strength of fused composites. However, the peeling strength of fused composites tends to be positively correlated to cloth cover of face fabric, resin weight, resin size and thinness of interlining. Under high cloth cover conditions, the dense constitution of the fabric obstructs the resin flow to the surface, reducing the strike-back of resin. As a result, more resin is caught between the face fabrics and interlinings making them adhere better. The interlining thickness stops the strike-back of resin. Under massive resin and coarse resin size conditions, adhesion between face fabrics and interlining is more effective, thereby upgrading peeling strength. In terms of THV, except for the twist factor of the face fabric and interlining yarns, temperature, time and pressure, a significant influence was noted in all other factors. Fused composites THV tends to be directly correlated to THV of face fabric, THV of interlining, cloth cover of face fabric, cloth cover of interlining and thinness of interlining. This condition was noted since the study uses the winter suit material handle to measure the THV standards of fused composites. When interlining and face fabrics were fused. Thickness increased consequently, increasing the fullness handle of the fused fabrics. The increase in cloth cover upgraded the density handle of fused composites, two conditions prerequisite to winter suit materials. Hence, as the THV and cloth cover of face fabrics and interlining increased, the THV of fused composites also increased. However, an increase in resin size would cause the fused composite THV to drop, showing a negative correlation tendency. This condition was noted under conditions where resin is coarse and abundant. Since the fused composite constitution was full of resin, a closelink structure was formed; consequently, the fused composite handle became hard, deteriorating the THV of fused composites. In short, the structural properties of interlining and face fabrics influence the three quality grades (strike-back of resins, peeling strength and THV) of fused composites.
The ideal fusing conditions of face fabrics and interlining This section attempted to understand the range of face fabric and interlining structural properties of fused composites possessing the ideal fusing quality grades. First, the discriminate analysis was used to group 60 pieces of samples in five post-fusion quality grade categories, see Figure 2. Then, the relationship between the face fabric, interlining and fusing conditions against fused composite quality grade were illustrated through the scatter plot. As shown in Figure 3, fused composite quality grade increased as face fabric total handle value, cloth cover and thickness increased; however it dropped as the yarn twist factor of face fabrics increased. Except for thinness, all other parameters had a linear relationship with the fused composite quality grade. Figure 4 showed that fused composite quality grades increased as interlining total hand value, thickness and cloth cover increased. In other words a linear relationship existed. As resin amount, resin size and interlining yarn twist factor increased, the fused composite quality grade declined; however this decline slowly converged after a certain degree was reached. In other words, the three properties have a nonlinear relationship with the fused composite quality grade. In terms of fusing conditions and fused composite quality grade, as shown in Figure 5, a cubic curve model was formed. The study was unable to separate the effects of fusing time, temperature and pressure on fused composite quality grade. This is principally due to the interdependence existing between temperature, time and pressure. During the fusion of interlining and face fabrics, the right temperature may cause the interlining resin to melt. The application of pressure will cause resin to permeate into the fabric layers, causing the adhesion of the interlining and the face fabrics. This process requires time for effective execution. If pressure on the interlining is removed too quickly, such that resin does not have sufficient time to melt at the right places, then adhesion strength of the fused materials will decrease. This effect is even more significant under low temperature and low pressure conditions. On the contrary, if fusing took too
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Figure 2. Scatter plot of canonical discriminate function
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Figure 3. Scatter plots of face fabric parameters and quality grades
Figure 4. Scatter plots of interlining parameters and quality grades
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Figure 5. Scatter plots of fusing conditions and quality grades
long, then resin will be too widespread or a strike-back condition will be effected. This affects the adhesion strength and handle of fused composites. This condition is even more significant under high temperature and high pressure fusing conditions. Hence, when fusing temperature, pressure and time are coordinated, then the ideal fusing effects are created (Lai, 1996; Shyr and Lai, 1997). Figures 6, 7 and 8 revealed the relationship between fused composite quality notch and fusing temperature, time and pressure. RBF refers to the predictor value of the fused composite quality grade of the artificial neural network model. The graphs revealed the ideal fusion quality under the median fusing temperature, time and pressure conditions. An observation of the preceding scatter plot allows one to categorize the five ideal fused composite quality level; scopes are shown in Table IV. The prediction of fused composite quality grade This section uses the artificial neural network to establish a face fabric and interlining structural properties and fusing conditions to predict fused
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Figure 7. The response surface among RBF, pressure and temperature
Figure 8. The response surface among RBF, pressure and time
composites quality level model. Since the study used a nonlinear predictor problem, thus it is best for the back-propagation network method to be used in resolution. The prediction ability is suitable for back-propagation network method solution. Therefore, these studies used 13 items in Table I as the network input value. Moreover, it was possible to conduct training using the fused composite strike-back of resin area, peeling strength, total hand value and total quality levels as network target value training for the establishment of four sets of predictor models. Training results were identified through the
Parameter Face fabrics THV Cloth cover Thinness (mm) Twist factor Interlining THV Cloth cover Thinness (mm) Twist factor Resin amount (g/cm2) Resin size () Fusing Time (sec) Temperature (8C) Pressure (kg/cm2)
Maximum Minimum 3.90 24.0 0.910 3.40 2.50 27.0 0.35 2.50 35.0 50.0 15.0 130.0 1.50
2.80 19.40 0.42 2.20 1.80 21.0 0.29 2.40 25.0 25.0 10.0 100.0 1.0
Mean 3.343 21.971 0.670 2.80 2.271 25.286 0.317 2.457 32.143 42.857 13.571 121.42 1.357
Standard deviation Variance 0.469 1.538 0.161 0.462 0.256 2.059 0.024 0.053 4.880 12.199 2.440 14.639 0.244
0.220 2.366 0.026 0.213 0.066 4.238 0.001 0.003 23.81 148.81 5.952 214.28 0.060
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Table IV. The parameter range of ideal fused composite quality grades
EMS value convergence. Figure 9 revealed that EMS dropped as training cycle increased. A multitude of training provides a better EMS convergence; as shown in Table V. In an attempt to understand the fitting capacity of the artificial neural network mode, a residual analysis was conducted on the network target value (actual fused composite quality levels) and post network training predictor value. Average value of residual absolute is defined as | Target value ± Predicted value | / Total number of samples. The larger the average value, the difference between target value and predicted value is greater, i.e. the model fit ability is worse. Results are shown in Table V. The average value of residual absolute of each model is between 0.1922 and 5.8468. This showed that each model has a very good predictor capacity. Figure 10 showed that through artificial neural network, the actual value of quality grade and the points on the predictor value scatter plot are all distributed at the diagonal matrix of the graph. The correlation coefficient of each model is
Figure 9. Error mean square plot
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greater than 87 percent. This clearly revealed that artificial neural network has a good effect on the fused composite quality grade predictions. Model tests This section evaluated the ideal of fused composites quality grades conditions and artificial neural network predictor capacity herein established. The model test results show that the number of samples having quality grades of ``good'', ``medium'' and ``poor'' are 2, 2 and 1, respectively. Since two samples have the same grade, only three samples having different grades are listed in Table VI to describe the test results. First, the structural property measurement separately obtained one sample each of the good, medium and poor quality grade interlining and face fabric combination. The actual quality grade of the fused composites was separately tested. The previously established artificial neural
Model
Table V. EMS and residual value of model
Figure 10. Scatter plots of the practical total quality and predicted values
Strike-back of resins (cm2) Peeling strength (kg/cm2) THV Total quality Note: Sample number: 60
Training cycles
EMS
Average value of residual absolute
11,900 12,000 10,400 11,200
0.0545 0.0445 0.0465 0.0657
5.8468 0.1922 0.2296 0.4945
Training example A
Training example B
Training example C
Face fabrics THV Cloth cover Thinness (mm) Twist factor
3.81 24 0.81 2.45
2.11 18 0.54 3.61
1.52 11 0.26 5.11
Interlining
THV Cloth cover Thinness (mm) Twist factor Resin amount (g/cm2) Resin size ()
2.38 25 0.32 2.22 35 25
1.51 18 0.21 3.01 35 50
1.32 11 0.14 3.86 50 100
Fusing
Time (sec) Temperature (8C) Pressure (kg/cm2)
13 120 1.3
10 100 1.0
20 150 2.0
Fused composites quality
Quality group Strike-back of resins (cm2)
Good 0
Medium 0
Poor 60
Parameter
Peeling strength (kg/cm2) THV Practical total quality grades Predicted total quality grades
3.6 4.1 5 4.61
2.3 2.8 3 2.82
1.8 1.5 1 1.98
network model was used to obtain the quality grade predictor value. The outcome is shown in Table VI. If example A is categorized according to Table IV, then it should be a good combination. Actual tests revealed that there are five quality grades. The artificial neural network model training obtained a predictor value of 4.61; within the five quality grade classes. Examples B and C are the medium and poor classes, respectively. Tests separately categorized them into classes 3 and 1. This showed that the ideal fusing condition range of face fabrics, interlining and fusing conditions are very appropriate and capable of successfully measuring the best face fabric and interlining combination. The quality measurement predictor model of fused composites can actually effectively predict the final quality grade of fused composites through face fabrics and interlining structural properties. Conclusion In summary of the above, face fabric and interlining structural properties as well as fusing conditions have a significant influence on fused composite quality. The ideal structural property scope of fused composites established in this study can provide fashion designers with face fabric and interlining matching choice references. The artificial neural network model training successfully established the predictor model for fused composite quality grades, thus providing fashion designers with the ability to predict the final quality grade of fused composites through their structural properties even
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Table VI. Predicted fused composite quality grades
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References Fan, J., Lee., W. and Hunter, L. (1997a), ``Compatibility of outer and fusible interlining fabrics in tailored garments, part I: desirable range of mechanical properties of fused composites'', Textile Res. J., Vol. 67 No. 2, pp. 137-42. Fan, J., Lee., W. and Hunter, L. (1997b), ``Compatibility of outer and fusible interlining fabrics in tailored garments, part II: relationship between mechanical properties of fused composites and those of outer and fusible interlining fabrics'', Textile Res. J., Vol. 67 No. 3, pp. 194-7. Fan, J., Lee., W. and Hunter, L. (1997c), ``Compatibility of outer and fusible interlining fabrics in tailored garments, part III: selecting fusible interlining'', Textile Res. J., Vol. 67 No. 4, pp. 258-62. Lai, S.-S. (1995), ``A study of the production of apparel interlining'', Journal of the China Textile Institute, Vol. 5 No. 6, pp. 447-53. Lai S.-S. (1996), ``A study of apparel interlining fusing technology'', Journal of the China Textile Institute, Vol. 6 No. 2, pp. 149-57. Lai, S.S. (1999), ``Establishing an objective handle evaluation model of fabrics part I: primary hand value'', Journal of Human Ecology and Technology, Vol. 1 No. 1, pp. 27-46. Lai, S.S. (2000), ``Establishing an objective handle evaluation model of fabrics part II: total hand value'', Journal of Human Ecology and Technology, Vol. 1 No. 2, pp. 141-9. Lin, C.H., Chiao, J.H. and Chou, H. (1997), ``A study on optimal combination of the face material and interlining of the men's winter suit-based on objective evaluation method'', Journal of the China Textile Institute, Vol. 7 No. 5, pp. 362-70. Potluri, P., Porat, I. and Atkinson, J. (1996), ``Low-stress fabric testing for process control in garment assembly application of robotics'', International Journal of Clothing Science and Technology, Vol. 8 Nos 1/2, pp. 12-23. Shyr, T.-W. and Lai, S.-S. (1997), ``The effect of fusing condition on thermal protective fabric'', The 78th Word Conference of The Textile Institute, pp. 489-96.
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A preliminary study of a deformable body model for clothing simulation Shigeru Inui
National Institute of Materials and Chemical Research, Ibaraki, Japan Keywords Clothing, Simulation, CAD
Study of a deformable body model 339 Received October 2001 Accepted April 2001
Abstract The body model which has been utilized in our clothing simulation does not deform and gives a boundary condition for mechanical calculation. To determine the shape of clothing in the case where clothing and body mechanically interact with each other, the body model used for this purpose has to be deformable. In this study, basic techniques for realization of the deformable body model were investigated. A tetrahedron was defined as a fundamental element for mechanical calculation of solid, and it was formulated with ordinal strain. Four kinds of cubes consisting of six tetrahedrons were defined as basic geometrical elements for constructing solids. Two kinds of cantilevers were constructed from the cubes and mechanical simulation was carried out with proper mechanical properties. A method of estimating internal mechanical properties of the human body was tested. The method is a modification of the simulation and is one of inverse problems. Treatment of collision is required for the simulation in which clothing and body mechanically interact with each other. The treatment of collision is based on a triangular element, and the processes consist of its detection and resolution. Simulation of a right cylinder solid wound by fabric like pipe was carried out to check collision treatment.
Introduction We have been developing a three dimensional apparel computer-aided design (CAD) system (a mechanical simulation for clothing) (Okabe et al., 1992). In the simulation system, a virtual solid shaped as a dummy or human body is dressed and the shape of clothing is predicted by mechanical calculation. The virtual dummy or human body in the system is defined as its surface shape. The surface consists of triangular mesh in the three dimensional space and is treated as it does not deform. So far as jackets or suits are simulated in the system, it is not a problem that the body model does not deform. On the other hand, in the cases of sports or inner ware, body and clothing exert force on each other and both of them are deformed, then the shape of them is determined in a state of stable equilibrium. To enable that kind of simulation in the system, we improve the body model from the present one, the shape of which is defined as fixed coordinates of its surface, to the new one which is defined as an elastic body and able to deform. External shape, internal structure and mechanical properties are the factors for defining the body model and the deformed shape of the model can be determined by mechanical simulation with those factors. Those factors relate to each other and the value of those factors should be obtained by measurement or another way for executing the calculation. This is a preliminary study to improve the body model, so we concentrate the investigation of body model formulation.
International Journal of Clothing Science and Technology, Vol. 13 No. 5, 2001, pp. 339-350. # MCB University Press, 0955-6222
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Theory and experiment In the simulation system we have been developing, the three-dimensional shape of clothing is predicted based on three factors of body shape, paper patterns and mechanical properties of fabric. The simulation method in this study is also static as the previous one (Inui and Yamanaka, 1998), and what this system can do is to predict the shape of clothing on a body in a certain posture. In the simulation, virtual paper patterns are divided into triangular finite elements for the demand of mechanical calculation. In a triangular element, it is assumed that the value of stress is constant. In the simulation program, virtual clothing is made up from virtual fabrics of the shape of paper patterns sewn together, and the calculation is started from the initial state in which the virtual clothing balloons out. The virtual fabric is deformed because of expansion from the original shape of plane paper pattern in the initial state of the simulation. Strain is calculated from the deformed shape and spatial arrangement of triangular elements. In the simulation system, generalized strain, which is utilized for the formulation of shell in the theory of elasticity, is adopted for the model of fabric. The strain excerted on the triangular element is calculated from the relationship between stress and strain expressed by a constitutive equation. After all, the internal stresses are calculated from deformed shape and spatial arrangement of triangular elements, and potential energy is obtained from the internal stresses and strains. The force which is exerted on a vertex of a triangular element is given as gradient of the potential energy at that vertex. A vertex is moved according to the magnitude and the direction of the force which is exerted on it so as to decrease the total potential energy. The value of potential energy differs when the shape and the spatial arrangement of triangular elements are changed by the movement of vertices of triangular elements. The vertices are repeatedly moved until the minimal value of potential energy is searched. The shape of virtual clothing in the state of minimal potential energy must correspond to that of real clothing. The paper pattern shape, which is one of the three factors of this simulation, gives the shape of triangular elements without strain. The body shape is considered as a boundary condition in the simulation, and the surface of the body exerts reaction forces upon virtual fabric. The mechanical properties of fabric are utilized as coefficients of the constitutive equation. Formulation of virtual body For construction of a virtual solid body should be mechanically formulated. The formulation of solid is basically the same as the case of fabric. For fundamental elements of solids, some kinds of solid figures can be considered. Here, a tetrahedron, with the surface divided into triangles, is adopted as the fundamental element of solid considering adaptability to the clothing simulation system. As strains of the three axes can be equally treated in the case of solid, ordinal strain is utilized instead of generalized strain in the case of fabric. In the calculation of clothing simulation system, it is necessary to locate a point on a plane containing the face of the triangular element independent of
its deformation, and areal coordinates are utilized for the purpose. Areal Study of a coordinates are another representation of plane coordinates based on triangles. deformable body The value of areal coordinates of a point, which is located on a plane containing model the face of a triangle, is determined from the area of three triangles that consist of the point and each edge of the triangle. Space coordinates of an arbitrary point on virtual fabric can be calculated from the areal coordinates and the 341 space coordinates of the three vertices of the triangular element. In case of solid, volume coordinates that are extensions of areal coordinates in the threedimensional space is adopted. The value of volume coordinates of a point is obtained based on a tetrahedron element, in the same way as areal coordinates, from the volume of four tetrahedrons consisting of the point and each triangles of the face of the tetrahedron element. The space coordinates of an arbitrary point are calculated from the volume coordinates and the space coordinates of the four vertices of the tetrahedron element. Definition of a solid A tetrahedron element is defined as the fundamental element for mechanical calculation of a solid, but a cube consisting of six tetrahedrons is the fundamental element to define geometrically a solid. A solid is constructed by piling up the cubes like bricks. Every face of a cube consists of two triangles, and the two triangles that compose a face of a cube located inside of a solid are held in common by two cubes. To pile up cubes without contradiction, four kinds of cubes, that consist of tetrahedrons in different manners, are needed (Figure 1).
Figure 1. Cube which is a unit for constructing solid shape
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Example of solid simulation A square pole and a right cylinder consist of the cubes as shown in Figure 2. The square pole has 14 steps of square solid figure consists of four cubes (Figure 2(a)), and the right cylinder has 20 steps of round solid figure consist of about 80 cubes. Simulations were carried out with those solid shapes treated as cantilevers. A cantilever is a beam that has the face of one end fixed and the other part free. The initial state of the simulation of the square cantilever is shown in Figure 3. The first simulation, the result of which is shown in Figure 4, is carried out in the condition that downward load is applied to every vertex on the face of the free end and gravity is not considered. Figure 5 shows the result of the simulation with the cantilever in the condition that gravity is applied to every tetrahedron element. Figure 6 shows the result of the calculation with the cylindrical cantilever in the same condition as Figure 4. Figure 7 shows the result of the calculation with the cylindrical cantilever in the condition gravity is applied to every tetrahedron element. Approximation of the mechanical properties of human body model It is a very difficult problem to determine the mechanical properties of each part of a real human body correctly. As a first approximation for the model, it is proper to assume as follows: (1) hard part, e.g. bone, is assumed to be rigid body which does not deform; (2) the volume modulus of deformable parts is the same value as water; (3) properly assume the modulus of longitudinal elasticity; (4) determine Poisson's ratio and the modulus of transverse elasticity from the assumptions above. The method of estimating mechanical properties Though the assumptions above seem to be appropriate as a first approximation, the mechanical properties of the human body should be measured because those depend on the region or condition in the human body.
Figure 2. Rod constructed from cubes
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Figure 3. The initial state of a square cantilever of Figure 2(a), the left end of which is fixed
Figure 4. The calculation result of the cantilever of Figure 2(a)
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Figure 5. The result of the cantilever simulation in which gravity is applied to every tetrahedron element
Figure 6. The simulation result of the cantilever of Figure 2(b) in the same condition as in Figure 4
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Figure 7. The result of cantilever simulation the condition of which is the same as in Figure 5
The way to measure the internal mechanical properties of living body ought to be non-destructive, but it seems to be difficult to measure those with that kind of measurement method. For example, internal structure of the earth is estimated by a method with the measurement of propagated seismic waves. Those types of methods are called ``inverse problem'' in general as follows (Musha and Okamoto, 1992): . .
.
the problem of estimating causes by the observation of results; the setting of the problem is different from the ordinal problem, i.e. solve differential equation under certain initial and boundary conditions; the problem of performing reverse transformation of certain integral transformations.
Here, it is tried as a preliminary test to estimate internal mechanical properties of a solid. In the test of estimation, we make the following two assumptions: (1) shape of solid in the condition that no strain is known. (2) internal structure of solid is known. The first assumption is accompanied by difficulties, but if the body shape can be measured in water we are probably able to obtain the shape. For the second assumption, we can obtain the internal structure of the body with the technique of computer tomography (CT). The following information has to be given to start the estimation process:
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initial value of mechanical properties for estimation; solid shape in the condition that there is no strain; shape of solid which is deformed with some loads.
The assumption process is executed in the following procedure: (1) calculate strains from deformed shape of solid in some loading condition; (2) simulate the shape from the initial condition that there is no strain with the current (initial or on the way of correction) value of mechanical properties; (3) calculate strains from the simulated shape; (4) calculate difference of the strains between the process (1) and (3); (5) correct the value of mechanical properties based on the difference of the strains. The processes from (2) to (5) are iterated until the difference of the strains becomes sufficiently small. An example of estimating mechanical properties of a solid Figure 8 shows the result of the calculation of the square cantilever in Figure 3 with uniform initial value of mechanical properties. Figure 8 shows the wire frame display of the side view of the cantilever, and Figures 9 and 10 are displayed in the same way. Figure 9 also shows the result of the calculation about the same square cantilever. The mechanical properties of the right side (from eighth step to fourteenth step) of the cantilever is set to be one tenth of the left side (from first step to seventh step). At the first correction of the mechanical properties in the estimation processes, the mechanical properties are corrected according to the difference between the strains calculated from the shape of the cantilever in Figures 8 and 9. The shape of the cantilever is
Figure 8. The result of the cantilever simulation in the same loading condition as in Figure 4
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Figure 9. The result of the cantilever simulation in the same loading condition as in Figure 4
simulated again with the corrected mechanical properties, and the simulated shape is utilized to obtain the difference of strains instead of that in Figure 9. The cycle of this simulation of the shape and correction of mechanical properties is iterated. Figure 10 shows the result of the simulation using the mechanical properties estimated by the procedure above. The shapes of Figures 10 and 11 are almost the same and the value of mechanical properties estimated from the procedure is also the same as that in Figure 10. The mechanical properties are occasionally well estimated in this case, but further investigations should be required in many aspects because this example is a very simple one. The mechanical properties are estimated from the response of a loading condition which is reflected as a deformed shape. For other loading conditions, the right response may not always be obtained as the result of calculation with estimated mechanical properties because the response is one of many solutions in the inverse problem. To respond properly to every loading
Figure 10. The result of the estimation of mechanical properties from the initial value of mechanical properties in Figure 8 and the shape in Figure 9 as final goal
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Figure 11. The forces between colliding objects
condition, it is necessary to estimate the mechanical properties without contradiction by correcting them based on the errors of the deformed shape in many loading conditions. For learning the method of the estimation, neural networks, for example, seems to be suitable. Collision between body and clothing In the case that the shape of clothing is determined by the interaction with the dressed body, the surface of the body is contacting with clothing and exerting forces in some places. To realize this interaction in the simulation, the problem of collision between objects should be treated in the program. The problem of collision consists of the detection and the solution. The detection of collision is a geometrical problem and the solution of collision is a mechanical problem. Detection of collision It is assumed that there is no self collision in this simulation, i.e. a triangular element never collides with another one on the same surface of fabric or solid. The fabric or the surface of solid in the simulation is divided into triangular elements. Therefore, collision can be considered based on triangular elements. The collision modes that two triangular elements are in contact with each other are classified as follows: . a vertex contacts a face of triangular element; . two edges are in contact. The processes of collision detection are divided into two stages. In the first stage, collision is roughly checked. Collision is examined about every edge of the triangular elements on the surface of objects. The vertex at the end of the edge is considered to be a control point, and a bounding box, the center of
which is the control point, is defined. If the bounding box contains a triangular Study of a element which is included in another object, the triangular element is listed up deformable body as that with which it might possibly collide. The distance between the vertex as model control point and listed up triangular element is calculated, and if the distance is less than a certain value, it is considered that the collision mode 1 is occurring (Figure 11(a)). We call the edge, the vertices at the end of which are control 349 points, the control edge. If there exists a triangular element which is listed up as the possibly colliding element for both vertices at the end of a control edge, the distance between the control edge and the edge of listed up triangular element is calculated (Figure 11(b)). If the distance is less than a certain value, it is considered that the collision of mode 2 is occurring. Solution of collision It is difficult to calculate forces between colliding objects precisely, and in this mechanical simulation, even if the forces are not completely correct on the way of calculation, the final equilibrium state is physically reasonable. Then a proper function of distance between objects is defined, and the forces between colliding objects are determined from the function. In the collision mode 1, the direction of the force is that of normal vector of colliding triangular element, and in the collision mode 2, the direction of normal vector of the plane formed by the two vectors in the directions of the two colliding edges. The forces between colliding objects of the collision mode 1 are shown in Figure 11(a). In the simulation, all the forces are treated as exerted only on the vertex of triangular or tetrahedron elements. The force, which is caused by collision and is exerted on the triangular element, is equally distributed to every vertices of the element for the simplicity of calculation. In the collision mode 2, the forces between colliding objects are shown in Figure 11(b), and those are equally distributed to both vertices at the end of the edge. The vertex is moved according to the resultant force which is exerted on it, including the force caused by collision, and the shape of clothing dressed on the body with the effect of collision is determined by the iteration of this processes. As an example, simulation, in which fabric like a pipe is wound around a cylindrical solid, is executed. The radius of the cylindrical solid is larger than that of the fabric like a pipe when there is no load. The calculation is started from the initial condition in which the radius of the solid is smaller than that of the fabric, and its result is shown in Figure 12. It is difficult to keep consistency in a collision problem, and this problem should be thoroughly examined. Conclusion When the shape of clothing dressed on a human body is determined by mechanical interaction between clothing and body, a deformable body model is required for simulation of clothing shape instead of conventional body model which does not deform. The problems to construct the deformable body model were searched out and investigated. A solid object is looked upon as an elastic body and mechanically formulated with ordinal strains. Then a fundamental
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Figure 12. The result of the simulation in which fabric like a pipe winds around a cylindrical solid
element for mechanical calculation is defined and the way of constructing a solid shape by combining the elements is determined. To realize the body model, external shape, internal structure and mechanical properties of it should be considered. The external shape of the human body can be measured by contact or contactless method of solid shape measurement. The information about the cross section of the human body can be obtained by the technique of CT and internal structure of the human body can be reconstructed from it. A roughly approximated value is given for mechanical properties and then a method to estimate those values is shown. To realize mechanical interaction between clothing and body in the simulation program, the treatment of collisions between objects is required. The simulation including interaction between solid and fabric was executed with the method of collision detection and solution based on triangular elements. In the way described above, the techniques for construction of the body model are examined. We expect to investigate the techniques more thoroughly, and to construct a valid human body model. References Inui, S. and Yamanaka, T. (1998), ``Seam pucker simulation'', International Journal of Clothing Science and Technology, Vol. 10 No. 2, pp. 128-42. Musha, T. and Okamoto, Y. (1992), Inverse Problem and Its Solution, Ohmsha, Tokyo. Okabe, H., Imaoka, H., Tomiha, T. and Niwaya, H. (1992), ``Three dimensional apparel CAD system'', Computer Graphics, Vol. 26 No. 2, pp. 105-10.
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A study on the needle heating in heavy industrial sewing Part 2: finite element analysis and experiment verification Qinwen Li
Productive Design Services Inc., Windsor, Ontario, Canada
Evangelos Liasi
A study on the needle heating
351 Received February 2000 Revised January 2001 Accepted January 2001
Ford Motor Company, Dearborn, Michigan, USA
Dan Simon
General Motors NAO Technical Center, Warren, Michigan, USA
Ruxu Du
Department of Industrial Engineering, University of Miami, USA Keywords Sewing, Finite element analysis, Infrared Abstract This is the second part of our study on needle heating in heavy industrial sewing. In this part, a finite element analysis (FEA) model is presented. Using a commercial FEA software system, ANSYS, the needle is modeled by a number of 3D bar elements and the sewing process is modeled by a series of time and space dependent boundary conditions. The model considers various important factors such as the needle geometry (including the point angle and point length of the needle), the friction between the needle and the fabric, the friction between the needle eye and the thread, the fabrics' material property, and the sewing conditions. It can predict needle heating in high accuracy. In order to validate the model, a large number of experiments were conducted, in which the needle temperatures were measured using infrared radiometry. It is found that the simulation results match the experiment results very well. Finally, a number of suggestions to reduce the needle heating are presented.
1. Introduction This is the second part of our study on the needle heating in heavy industrial sewing. In Part 1 of the paper, two analytical models are presented (the sliding contact model and the lumped variable model). These models are relatively simple to use (though the mathematics is tedious) and, hence, can be used to estimate the needle heating on the shop floor. However, they are simplified models and, hence, the prediction accuracy is limited when the sewing speed is high (over 2,000rpm) and/or the fabric is thick (over 8mm). The work was completed when Qinwen Li, Evangelos Liasi and R. Du worked at the University of Windsor, Windsor, Ontario, Canada. This work was partially supported by Delphi Lighting and Interior Systems, Peregrine Canada, and the Natural Science and Engineering Research Council of Canada (NSERC). In particular, we would like to thank Charles Beauchampe, who made the success of this project become possible. Many thanks are extended to Annette, our expert sewer from Peregrine Canada as well as Mr Dennis LeMioux who has graciously extended his services when carrying out the high speed IR experiments.
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In this paper, a finite element analysis (FEA) model is presented. According to the literature survey, as presented in Part 1 of the paper, few theoretical models have been developed and no FEA model has been found. This is due partially to the fact that needle heating is a complicated process involving many factors such as time-variant boundary condition, complex geometry and different materials. On the other hand, such a model is very important as it can predict the needle heating accurately without expensive experiments. Also, it provides valuable information for needle design and sewing process optimization. The following of the paper is divided into three sections. Section 2 describes the FEA model and the simulation results. In order to validate the model, a large number of experiments were conducted. Section 3 presents the experiment results and discusses several important discoveries. Finally, section 4 contains the conclusions and the suggestions on how to reduce needle heating. 2. The FEA model In Part 1 of the paper, the needle heating process has been discussed in detail. In short, within each stitch the heat is generated by: . The heat flux generated from the friction between fabric and needle. . The heat flow generated from the friction between thread and needle eye when thread is in tension. On the other hand, the heat is dissipated through: . The convection of the portion of the needle surface that is not in contact with the fabric. . The conduction in the needle from the higher temperature points to the lower temperature points. . The conduction to the fabric, since the needle is hotter. . The conduction to the thread, which happens when the thread is not in tension and hence, passes through the needle eye loosely. . The radiation from the needle surfaces to environment. In addition, it is noted that as the sewing process progresses, the needle temperature rises from an initial temperature to a steady state. After that the needle temperature oscillates slightly within each stitch following the needle motion. Owing to the relative motion between the needle and the fabrics, both the heat sources and the heat sinks are time-dependent and, hence, needle heating is a transient heat transfer problem. In our study, a commercial FEA software system, ANSYS, is used to model and solve the needle heating problem. Since the problem is time-dependent, a program is developed using ANSYS parametric design language (APDL). The program defines the needle geometry meshing, specifies the time-dependent boundary conditions, specifies the solution method, and defines the result viewing. Following is a detailed description of the FEA model.
2.1. Modeling the needle It is known that there are over 100 different types of industrial sewing needles in the market. They have different lengths, diameters, shape of the lead, and shape of the cutting point. Typically, an industrial sewing needle is defined by some 15 parameters, including the needle lead shape, needle eye position and size, groove position and size, etc. Each one of these parameters may contribute to the needle heating with different degrees of significance. In our study, in order to simplify the model, a needle is modeled as a number of solid bar elements (SOLID70 elements). As shown in Figure 1, the needle is meshed to approximately 500 nodes using the ANSYS automatic mesh generation function. More specifically, the needle geometry is defined by the following parameters:
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ndiv = number of divisions along on the needle length (typically, ndiv = 30); nlg
= needle length [m];
rad(i)= needle radius on the ith section [m], i = 1, 2, 3, . . . ndiv; lgb
= the beginning position of the groove [m];
lge
= the end position of the groove [m];
hb
= the beginning position of the needle eye [m];
he
= the end position of the needle eye [m];
dp
= needle penetrating distance [m];
Note that the number of divisions, ndiv, determines the mesh size. The larger the ndiv, the smaller the mesh size. Also, since the needle is symmetric, only half of the model is used in the analysis.
Figure 1. The FEA meshing of the needle
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2.2. Boundary conditions The boundary conduction describes how the heat sources and the heat sinks are applied to the needle heating. Since the boundary conditions are timedependent, it is necessary to use load steps. Specifically, in the model, each stitch is divided into a number of load steps. At each load step, a set of boundary conditions is applied. The boundary conditions are determined based on the following assumptions: . .
.
The needle speed is a constant during penetrations and withdraws. The material properties of the needle and the fabric do not change during the sewing process. The top and bottom fabrics have the same thermal properties. In other words, the friction heat is generated uniformly over the entire contact area.
.
The heat lost owing to the radiation is negligible.
.
The friction coefficient does not change.
In addition, as illustrated in Figure 2, the sewing conditions are characterized by the following parameters: rpm = rotation speed of the punching crank [rpm];
Figure 2. Illustration of the three time periods in a stitch
th
= fabric thickness [m];
dp
= needle penetration distance [m];
dw
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= needle idling distance [m]; 2
fcoef = convection coefficient of the needle's outer surface [W/m 8C]. Following the assumptions above, three sets of boundary conditions are included in the model: (1) the heat flux from the friction between the fabrics and the needle; (2) the heat flow from the friction between the thread and the needle eye; and (3) the convection from the needle. 2.2.1 The heat flux from the contact between the needle and the fabric. The generation of the heat flux is time-dependent. As shown in Figure 2, one sewing cycle (one stitch) can be divided into three different time periods: penetration, withdraw, and idle. The heat flux is generated in the first two time periods. Assuming that the needle speed is a constant, the needle speed can be expressed as follows:
dp dw 2 spd rpm
1 60 where, spd is the needle punching speed [m/s]. Imaging that the each stitch is divided into a number of load steps. The time of each load step is: th time
2 spd At each load step the number of elements in the needle that would experience heat flux is given by: th nshf Nint
ndiv
3 nlg where, Nint(x) is an ANSYS function used to calculate the nearest integer to x. The number of load steps in the penetration time period is given by: dp kp Nint
th
4
The number of load steps in the idle time period is given by: kw Nint
dw ; th
5
Finally, the total number of load steps in one cycle is: T load 2
kp kw
6
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Figure 3 illustrates how the heat flux boundary conditions are being applied section by section at different load steps. In this case, the fabric thickness is 2mm, and the needle is divided into 30 sections. At each load step, the heat flux is calculated based on the friction power expressed as: Pf f
t
t
7
where, Pf is the friction power [W], f(t) is the friction force between the needle and the fabric [N], and (t) is the needle speed [m/s]. Note that the sewing force consists of two components: the cutting force and the friction force. Only the friction force contributes to the heat generation (Mallet and Du, 1998). Based on equation (7), the heat flux is obtained using the flowing equation: qflux
Pf Asection
f
t
t 2r th
8
where, qflux is the heat flux [W/m2]; Asection is the needle contact area that experiences heat flux [m2]; and r is the needle radius [m]. The friction force can be calculated using the method presented in (Mallet and Du, 1998). Figure 4 shows an example of friction force as a function of time in one stitch. As shown in the figure, in the penetration period, as the needle pierces through the fabric the friction force increases from 0 to a certain constant. Then it remains relatively unchanged. The constant friction force can be determined by: f 2rthpu
9
where, r is the radius of the needle, p is the specific normal force that fabric acts on the needle [N/m2], is the friction coefficient between the needle and the fabric. Note that within a stitch, the friction force, f, is not a constant (Mallet and Du, 1998). Furthermore, the friction force density is defined by: fdensity
Figure 3. Applying the heat flux boundary conditions layer by layer
f p 2r th
10
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Figure 4. An example of friction forces vs. time
Note that fdensity is the specific friction force over the contact area between the needle and the fabric. It is a function of material properties, but is independent of the fabric thickness and the needle velocity. Combining equations (8)-(10), it follows that the heat flux can be determined by: qflux fdensity spd p spd
11
It should be pointed out that the specific normal force and the friction coefficient are material dependent. 2.2.2 The heat flow and the heat conduction between the needle eye and the thread. The heat flow is generated as the result of the friction between the needle eye and the (top) thread. As stated earlier, the thread plays a complicated role in the needle heating. Depending on its state of tension, the thread can be a heat source or a heat sink. In particular, when it is in tension, it rubs the needle eye and, hence, becomes a heat source. On the other hand when it is not in tension, its contact with the needle will carry heat away and, hence, is a heat sink. In order to determine the heat flow, the thread motion in a stitch must be studied. Figure 5 illustrates the motion of the top thread within a stitch and Figure 6 shows how the thread tension changes with the rotation angle of the main crank shaft. As shown in Figure 6, the thread is loosely in contact with the needle eye most of the time. In particular, the thread is in tension before the needle penetrates the fabric and after the needle withdraws from the fabric. During these two periods of time, the heat flow is generated. In order to simplify the calculation, only the average value is considered. As shown in Figure 7, suppose that the thread tension is T, the needle diameter is d, and the needle eye diameter is h; then, the normal friction force N can be determined by: 1 2 90 N 2T cos
12 2
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Figure 5. A sketch of thread motion and tension in the thread
Figure 6. A sketch of thread tension within a stitch
where, 08 < 1 < 158 represents the possible angle between the thread and the needle before the thread goes into the needle eye, and 2 = atan(h/d) represents the angle between the thread and the needle when the thread goes through the needle. The friction force is given by: f N
13
Pfriction f Vthread
14
and the friction power is:
Vthread is the thread velocity relative to the needle.
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Figure 7. Heat flow calculation
It is noted that the heat flow is also partitioned between the needle and the thread. The partition ratio, thread , can be calculated using an empirical equation (Li, 1998):
thread
1 e t t
T T0
15
where, t is the thread property coefficient; T0 is the environment temperature [K]; t is the speed coefficient, 0 < (t < 1; and T is the reference temperature of the needle [K]. In practice, t and t are empirical constants and can be obtained from experiments. Figure 8 shows several examples of the partition ratio at different sewing speeds of different fabrics. From the figure, it is seen that at the beginning of a sewing operation, the majority of the friction heat is absorbed by the needle because the conductivity of the thread is small. As the sewing operation progresses, the needle temperature reaches a steady state. At this time, the majority of the heat goes to the thread. When the thread is not in tension and it is in contact with the needle, it carries the heat away. However, since the thread may or may not contact the needle eye, the calculation of the heat sink is rather complicated. To simplify the calculation, only an average value is considered: suppose that within a stitch, the amount of the thread that goes through the needle eye is t Volt , where t is a coefficient and Volt is the needle speed. Furthermore, suppose that the average temperature in the thread decreases from T to Tinfinity; and the temperature in the needle eye is Te. Then, the following empirical equation gives an estimation of thread cooling effect on the needle eye in a stitch (Li, 1998): t
vol t ct Volt
T T1 =t Te Ttt
16
where, t is the thread cooling coefficient [W/8C]; vol is thread volume coefficient representing the depth of heat penetration in thread; t is the time of a stitch [s]; Ttt is the thread temperature, T1 < Ttt < T.
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Figure 8. The heat partition ratio vs. sewing stitch cycle
In equation (16), the numerator represents the total amount of heat absorbed by the thread in one stitch. It is determined by the material property, the size of the thread, as well as the needle speed. On the other hand, the denominator is the difference between the needle temperature and thread temperature. The cooling effect parameter t can be obtained from experiments as well. In our experiment, as described in the following section, it was found that t 0.004 [W/8C] for unbounded thread and t 0.001 [W/8C] for bounded thread. Though, the sewing speed seems has little effect on t : It is interesting to note that the thread-protecting groove in the needle is very important. If it can perfectly accommodate the thread when the needle is penetrating into and withdrawing from the fabric, then the friction between thread and fabric will be minimized (Hersh and Grady, 1969). Consequently, the heat flow can be ignored. Therefore, it is important to have matched the needle and the thread. In particular, one should not use undersized needles, which will generate additional friction and, hence, additional heat. 2.2.3. The heat convection of the needle. As the needle becomes hot, heat convection will take place between the needle surface and the environment. As pointed out earlier, within a stitch the temperature is constantly changing. As a result, the heat convection changes constantly. In order to simplify the model, however, it is assumed that the heat convection coefficient is a constant within a stitch. This is due to the fact that the sewing speed is high and hence, one stitch takes only a millisecond. In such a short period of time, the variation of
the needle temperature will be small and, therefore, it is reasonable to assume that the heat convection coefficient is a constant. In the model, the boundary condition that represents the heat convection is applied in a similar manner as the heat flux. As shown in Figure 3, the sections of the needle that are not generating heat flux are those which undergo heat convection. According to Perry (1963), the heat transferred by convection can be expressed as: Q Ahc T
17
where, A is the convection area of the needle in [m2]; hc is the convection coefficient [W/(m2VK)]; and T is the temperature difference between needle surface and environment [K]. The convection coefficient hc is related to many factors, such as the thermal property of the needle (k; ; ; cp ), the shape, size, and position of the needle, as well as the sewing speed. According to Perry (1963), it is about 12[W/(m2K)] for the natural convection from a vertical cylinder in room temperature. Under forced air flow at a velocity of 3[m/sec], it is about 170[W/(m2K)]. According to our study, the steady state needle temperature would not be significantly different as hc changes from 80[W/(m2K)] to 120[W/(m2K)], which corresponds to the sewing speed changing from 500-2,000rpm. Therefore, an average value, hc = 100[W/(m2K)], is used in the model. 2.3. Simulation results The needle heating model presented above is solved using the build-in solver of ANSYS. In order to simulate the process of needle heating of eight seconds, approximately 1,000 load steps are required. Each simulation takes about eight hours on an IBM PC compatible computer with Pentium 486 processor. It shall be noted that the model contains a number of constants such as the specific normal force and the friction coefficient. These constants may effect the simulation results significantly. The reader is referred to Li (1998) for details. A number of simulations were carried out at sewing speeds of 500, 1,000 and 2,000rpm and fabric thicknesses of 2mm and 4mm. Figure 9 shows a typical temperature distribution in absolute temperature scale (sewing speed = 2,000rpm, fabric thickness = 4mm). It is seen that the highest temperature occurs at the needle eye (454.98K at node S9). Figure 10 shows the temperature rise of selected nodes in the same example. From the figure, it is seen the needle eye reaches the maximum temperature in about three seconds. 3. Experimental validation and discussion In order to validate the presented models, a number of experiments were conducted on a PFAFF industrial sewing machine. The detailed experiment setup is discussed in Liasi et al. (1999). Briefly, the needle temperature was measured using several different infrared imaging devices, such as an infrared
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Figure 9. A simulation result showing the needle temperature distributions
Figure 10. Temperature rise at different needle locations
line scanning camera and a high speed infrared camera. Experiment conditions were the same as the simulation. It should be noted that the experiments were sewing thick industrial fabrics, which may be significantly different from sewing apparel fabrics. Figure 11 shows a typical needle temperature distribution captured from a high speed infrared camera. Comparing with Figure 9, it can be seen that the experiment result matches the simulation result very well. Figure 12 shows the maximum needle temperature profiles at selected sewing speeds (the fabric thickness is 4mm). Note that owing to the limitation of the equipment, the needle temperatures were measured in discrete time (every three seconds or so). In particular, the swing condition of the experiment presented in Figure 12(a) is the same as that in Figure 9. Comparing the two figures, it is seen that the trends of the temperature rise are the same. Also, in the simulation, the maximum temperature is 4508K ± 297 = 1538C; in the experiment it is approximately 1608C. In addition, the time constants (i.e. the time required to reach 68 percent of the steady state temperature) of the two sets of data are about the same (0.7 second). Tables I and II summarize the simulation results using different simulation models (including the sliding contact model and the lumped variable model discussed in Part 1 of our study, and the FEA model discussed in this paper) with a comparison to the experimental results. From these tables, the following observations can be made:
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(1) All the simulation models worked well. In particular, the average error (peak temperature) is 25.6 percent for the sliding contact model, 24.2 percent for the lumped variable model, and 7.7 percent for the FEA model.
Figure 11. A typical IR image
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Figure 12. Peak needle temperature profiles
(2) The factors that effect needle heating, ranked according to their significance, are: . sewing speed; . fabric thickness; and . the material properties of the fabric and the needle. (3) With the increase of the sewing speed, the time constant decreases. In other words, the needle will take a longer time to reach the maximum temperature. This is perhaps due to the fact that the rapid increase of the needle temperature also increases the heat conduction and heat convection. A direct implication of this discovery is that if the seam is relatively short, then the high speed sewing will have little affect on the needle heating.
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Furthermore, using the simulation models and the experiment testing, the following discoveries are made: . The material properties of the needle and the fabric will effect the peak temperature and the time constant. This is done through the friction coefficient, which determines the friction force. A direct implication of this discovery is that using smooth needles and/or using lubricant will reduce the needle heating. In other words, needles should be changed regularly. . The heat partition between the needle and the fabric plays an important role. It is a function of the material properties of the needle and the fabric as well as the temperature difference between the needle and the fabric. Hence, it is possible to reduce the needle heating by changing the material property of the needle, such as using materials that have high thermal conductivity. . The needle geometry plays a minor role in needle heating. In particular, according to the simulations on two different needle diameters (2.4mm Sewing speed (rpm) 2,000 1,000 500
Sewing speed (rpm) 2,000 1,000 500
Sliding contact model
Lumped variable model
FEA model
Experiment results
197 145 109
195 140 110
180 127 87
177 117 77
Sliding contact model
Lumped variable model
FEA model
Experiment results
0.25 0.5 0.8
1.1 1.5 1.8
0.6 0.8 1.45
0.75 1.4 1.75
Table I. Peak temperature prediction and experiment results
Table II. Time constant prediction and experiment results
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and 2mm), the peak temperature has no significant difference. This is perhaps because the friction heat increases as the needle diameter increases; at the time, the convection heat loss also increases which offsets the needle temperature increase. The frictions between the needle eye and the thread usually raise the needle temperature by 5-78C. This is why the peak temperature is usually found around the needle eye.
Finally, it is interesting to find what causes errors in the sliding contact model and in the lumped variable model. In the sliding contact model and the lumped variable model, the needle geometry is simplified as a cylinder and the friction heating between the needle eye and the fabric is not considered. In addition, in the sliding contact model, only the needle surface is considered in the heat conduction, though the heat conduction along the needle is considered. In the lumped variable model, the heat conduction along the needle is ignored but the entire needle cross section is considered in the heat convection. Based on the FEA model, the temperature on the center of the needle is nearly the same as the surface. This gives support to the lumped variable model. Also, it is found the temperatures on the needle surface oscillate more than that of the needle center. Therefore, the peak temperature obtained from these two models is higher, but the lumped variable method is slightly better. 4. Conclusions This is Part 2 of our study on needle heating. In this paper, a FEA model for the needle heating is presented. Given needle geometry, sewing condition, and fabric property, the model can predict the needle heating process, including the initial heating and the steady state. Based on the infrared measurement in the experiments, it is found all three models (the sliding contact model and the lumped variable model presented in Part 1 and the FEA model in this paper) work reasonably well. In particular, the first two models have an average error (peak temperature) of about 25 percent, though their calculations can be done in seconds. The FEA model is very accurate with an average error of less than 10 percent. However, it requires much more computation. Based on our study, a number of remedies are found to reduce the needle heating. These are: . Use needles with smooth surfaces. In other words, change needles regularly. . Use matched needle and thread. In particular, if the thread is too big (i.e. the needle groove is too small to accommodate the thread), then much more heat will pass to the thread and, hence, reduce the strength of the thread. . Use lubricant or other coolant device. . Use matched needle and fabrics. This will reduce the friction heating as well as the heat partition between the needle and the fabrics and, hence, reduce the needle heating.
The authors felt that there are still many problems in needle heating. For example, it is expected that the needle life is related to the needle temperature. Also, it seems possible to alter the geometry of the needle (such as the shape of the cutting points, the angle of the cutting point, and the coating of the needle) to reduce needle heating. All these remain to be the topics of future studies.
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References Hersh, S.P. and Grady, P.L. (1969), ``Needle heating during high-speed sewing'', Textile Research Journal, Vol. 39, pp. 101-20. Li, Q. (1998), ``A study on the industrial sewing needle heating'', Master's Thesis, University of Windsor. Liasi, E. et al. (1999), ``Heating of an industrial sewing machine needle'', accepted for publication by International Journal of Clothing Science and Technology. Mallet, E. and Du, R. (1998), ``Finite element analysis of sewing processes'', International Journal of Clothing Science and Technology, Vol. 11 No. 1, pp. 19-36. Perry, J.H. (Ed.) (1963), Chemical Engineers' Handbook, 4th ed., McGraw-Hill, New York, NY.
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COMMUNICATIONS The interrelationship between fabric crease recovery and pressing performance J. Fan
Institute of Textiles and Clothing, Hong Kong Polytechnic University, Hong Kong Keywords Fabric, Clothing industry, Garments Abstract Creases are marks that are created and left in a fabric during garment wear. Pressing is a process to flatten garment panels and sharpen garment edges and pleats. To minimize crease, the fabric should recover after pressing without creating a creased edge. Whereas, good pressing performance means the creased edge stays sharp after pressing. Good crease recovery and pressing performance appear contradictory. However, crease recovery and pressing performance are different as creases are formed during wear and pressing is carried out using pressing equipment such as iron, pressing machines, etc. The condition, i.e. temperature and humidity, under which the creases are formed in wear and pressing are very different. The latter has much higher temperature, pressure and humidity. This paper reports on an experimental investigation on the relationship between the crease recovery and pressing performance of wool and other fabrics. It was found that there are only generally weak to moderate relationships between the crease recovery as measured by the Shirley Crease Recovery Tester and the pressing performance as measured by the Siro-Press Tester. The characteristics of wool fabrics, which have both good crease recovery and pressing performance, are identified. This study is a step towards fabric engineering.
International Journal of Clothing Science and Technology, Vol. 13 No. 5, 2001, pp. 368-375. # MCB University Press, 0955-6222
Introduction Garment appearance is very important to today's consumers. Consumers require clothing free from creases and wrinkles during wear and having lasting sharp crisp edges and pleats. Creases or pleats may be intentionally created by the pressing operation to achieve the desirable appearance. Creases unintentionally created during wear are however undesirable. There is apparently contradictory requirement on the fabric, viz. it should be easily creased to sharp edges during pressing, but difficult to be creased during normal wear. The difference between the two types of creases is the condition under which the creases are formed. During wear, the creases are formed under lower temperature, humidity and stress, whereas, during pressing, the creases are formed under higher temperature, humidity and pressure. In effect, we want fabrics which have very different crease forming behavior under the two conditions. Is it possible? How is it possible? In order to find these answers for fabric engineering, we investigated the relationship between the fabric crease recovery and pressing performance, so as to identify the characteristics of fabrics which have both good crease recovery and pressing performance.
Experimental Samples We selected ten wool fabrics, ten cotton fabrics and ten polyester fabrics. Each category of fabrics has a wide variation in mass. The details of the samples are listed in Table I. To eliminate any possible ageing effects, the fabrics were deaged by soaking in 208C water for 30 minutes, then followed by centrifugation, steam pressing and conditioning. Crease recovery test The fabric crease recovery was measured using the Shirley Crease Recovery Tester. Six specimens (40mm 15mm) in each direction were prepared and tested to obtain the average crease recovery angles. The warp crease angle was measured when the warp yarns were folded, and the weft crease angle when the weft yarns were folded. The specimens were conditioned for at least 24 hours in the standard atmosphere before testing. The tests were carried out at 208C. The test specimens were folded and compressed for one minute under 500g to create a fold. They were then suspended in a test instrument for a recovery period of five minutes, after which the recovery angle was recorded. Press test Fabric pressing performance is evaluated by using the Sirolan Press Tester. Fabric samples used for the testing were conditioned in the standard atmosphere for at least 16 hours before cutting took place to prepare the specimen. Three warp and three weft specimens 40mm 20mm were tested. The specimens were folded back to back and pressed in a sealed jig, which was placed in the boiling water for 3.5 minutes and then in the cold water (15-258C) for 3.5 minutes. The press angle was measured after the pressing. Results of crease recovery and press angles are also listed in Table I. Results analysis and discussion Figure 1 shows the relationship between the warp crease recovery angle and warp press angle (folding the warp yarns). As can be seen, the relationship is quite strong with the correlation coefficient of 0.75. This means, in the warp direction, good crease recovery may correspond to poor pressing performance. As most seams are parallel to the warp, i.e. folding the weft. The weft press angle is normally more important. Figure 2 shows the relationship between the weft crease recovery angle and weft press angle. As can be seen, the relationship is very weak. This implies that, for wool fabrics in the weft direction, there is very little dependence between the crease recovery and pressing performance. In other words, it is possible to have fabrics having high crease recovery and small press angle. Among these ten samples, fabric W8 is the most desirable. It has a high crease angle (the mean crease recovery angle is 1668) and very small press angle (mean press angle is 11.88). It is a heavy worsted fabric having a mass of 464g/m2. Its weave is 3/1 twill. It is in plain dark blue, so it is probably piece dyed.
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Mass (g/m2)
Crease recovery angle (8) Warp Weft
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Table I. Details of fabrics used in the experiments and testing results Sett or density (yarns/cm) Warp Weft
Press angle (8) Warp Weft
Sample no.
Fibre content
Colour
Weave
W1
100 percent woollen
Twill
16
15
255
160
160
20
W2
100 percent woollen
Herringbone
11
12
265
164
170
20
22
W3 W4
100 percent worsted 60 percent mohair, 40 percent worsted 100 percent worsted
Brown and black, colour woven Orange and brown, colour woven Plain back Plain black
Cord Plain
37 18
30 20
227 186
161 164
172 163
23 21
45 24.5
Twill
22
19
209
165
166
36.5
35.5
Twill
33
24
280
161
166
23.5
24.5
Crepe
35
25
277
166
168
24.5
12.5
Twill Twill Twill Twill Twill Twill Twill
30 37 30 32 24 47 44
36 33 20 18 19 24 22
464 413 236 343 165 235 268
156 158 156 116 111 103 96
176 161 161 113 107 96 101
11 17 16 14.5 31 22 18.5
W5 W6 W7
98 percent worsted, 2 percent polyurethane 100 percent worsted
W8 W9 W10 C1 C2 C3 C4
100 100 100 100 100 100 100
percent percent percent percent percent percent percent
worsted worsted worsted cotton cotton cotton cotton
Green and black, colour woven Grey, Melange Black and white, colour woven Plain black Plain black Plain blue White Yellow Blue Black
21
12.5 17.5 19 20 31.5 26 18.5 (continued)
Sett or density (yarns/cm) Warp Weft
Mass (g/m2)
Crease recovery angle (8) Warp Weft
Press angle (8) Warp Weft
Sample no.
Fibre content
Colour
Weave
C5
100 percent cotton
Fancy
28
35
242
104
88
18
6
C6
100 percent cotton
Jacquard
27
25
184
93
91
17
9
C7 C8 C9 C10 P1 P2 P3
Twill Plain Corduroy Twill Plain Satin Twill
29 39 9 27 52 109 47
17 17 41 18 36 38 24
252 157 189 501 122 91 248
86 93 109 78 144 158 126
112 99 128 106 144 154 132
26 46 27 17 12.5 13 18.5
12 52 34 8 12 21 16
Red
Twill
43
23
213
133
137
21.5
22.5
P5 P6 P7
100 percent cotton 100 percent cotton 100 percent cotton 100 percent cotton 100 percent polyester 100 percent polyester 65 percent polyester, 35 percent cotton 65 percent polyester, 35 percent cotton 100 percent polyester 100 percent polyester 100 percent polyester
Blue and white, colour woven Blue and white, colour woven Denim blue White Red Denim blue Orange Pink Green
Plain Twill Plain
24 45 44
19 41 37
181 119 77
160 140 132
154 134 136
18 10 17
20 10 16
P8
100 per cent polyester
Plain
42
37
64
128
128
24
21.5
P9 P10
100 percent polyester 100 percent polyester
Brown Red Green and white, colour woven Pink and white, colour woven White White
Plain Plain
68 44
36 44
96 94
142 130
113 157
10 13.5
16 6
P4
Fabric crease recovery
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Table I.
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Among the ten samples, the most undesirable fabric is probably W5. Although it has good crease recovery, it is poor in pressing performance with the mean press angle of 368. This is a colour woven fabric in 2/1 twill with a mass of 209g/m2. It is speculated that colour woven fabrics tend to have higher press angles (poorer pressing performance) than piece dyed fabrics. Out of the ten wool fabric samples, the mean press angle of the five definitely colour woven fabrics is 25.68. The mean press angle of the five possibly piece dyed fabrics (single colour) is 20.68. Figures 3-6 show the relationships between the crease recovery angle and press angle of polyester and cotton fabrics in the warp and weft directions,
Figure 1. Warp crease recovery angle vs. warp press angle for wool fabrics
Figure 2. Weft crease recovery angle vs. weft press angle for wool fabrics
Figure 3. Warp crease recovery angle vs. warp press angle for cotton fabrics
respectively. As can be seen, there is virtually no relationship between the crease recovery angle and press angle. This means the crease recovery and pressing performance are independent of each other. Or in other words, one can produce cotton and polyester fabrics with good crease recovery and pressing performance. The weak to moderate relationships between the crease recovery angle and press angle can be understood by the different mechanisms involved in the crease formation. During normal wear, the temperature and humidity, under which the creases are formed, are much lower than those during pressing. As far as crease recovery is concerned, the creases are recovered under normal wear by overcoming the internal viscoelastic and frictional components
Fabric crease recovery
373
Figure 4. Weft crease recovery angle vs. weft press angle for cotton fabrics
Figure 5. Warp crease recovery angle vs. warp press angle for polyester fabrics
Figure 6. Weft crease recovery angle vs. weft press angle for polyester fabrics
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(Chapman, 1974). Fabrics having high bending rigidity, low viscoelasticity and low internal friction will tend to have better crease recovery and wrinkle resistance. Based on this understanding, blending wool fibres with stiff and resilient fibres, heavy weight fabrics, long float weave structure and finishing operations (e.g. crabbing, scouring, etc.) for reducing fibre-to-fibre and yarn-toyarn friction should improve the fabric crease recovery. During pressing, the temperature of the fabric is increased to above its glass transition temperature. The glass transition temperature of wool is related to its moisture regain. During the press test, the moisture regain of wool fabric is about 16 percent and the glass transition temperature is about 608C. When the testing jig containing the specimens is placed in the boiling water for 3.5 minutes, the temperature of the fabric is increased to 1008C, i.e. above the glass transition temperature. Under such condition, cohesive set in wool fibres takes place involving the rearrangement of hydrogen bonds in the fibre (De Boos, 1987). It is understood that higher pressing temperature and higher moisture content (ensuring the temperature well above the glass transition temperature) can improve the pressing results. However, little is understood of the relationship between the fabric properties and its pressing performance. In other words, what fabric can be better pressed under the same pressing condition? Leung (2000) investigated the relationship between the fabric's low stress mechanical properties and its pressing performance. Virtually no relationship could be found. She found, contrary to conventional belief (Biglia et al., 1991), fabric pressing performance is not related to fabric hysteresis. It has been reported that wool fabrics for pleating should have relatively high relaxation shrinkage and low hygral expansion. Could the press angle be related to these two dimensional properties? The experimental data published in Biglia et al.'s (1991) paper was used to investigate the relationship between the press angles and the dimensional properties and other low stress mechanical properties. The sample size of the data was 84 light weight worsted fabrics. The stepwise variable selection method of the multiple regression analysis was used to select the parameters most related to the weft press angle from 13 FAST mechanical and dimensional properties. Weft hygral expansion, weft relaxation shrinkage, warp hygral expansion, shear rigidity and warp bending rigidity were found to be the more relevant properties than others. The following empirical relationship was established with a correlation coefficient R = 0.606, i.e. Weft Press Angle 48:5 2:69HEwt 3:10RSwt 3:33HEwp 0:387G 0:496 Bwp; where HEwt is the weft hygral expansion, RSwt the weft relaxation shrinkage, HEwp the warp hygral expansion,
G the shear rigidity and Bwp the warp bending rigidity. From this relationship, it can be seen that relatively higher hygral expansion and relaxation shrinkage tend to result in better pressing performance (lower press angle). In practice, the effect of shear rigidity may be balanced by the effect of bending rigidity. This finding is in agreement with the mentioned speculation that piece dyed fabrics tend to have better pressing performance. Conclusions The relationship between the fabric crease recovery and pressing performance is considered in the paper. It was found there is only weak to moderate interrelationship between the two fabric properties. It is therefore possible to engineer fabrics to have high crease recovery angle (good wrinkle resistance) and small press angle (good pressing performance), once we understand how fibre properties, fabric construction, and manufacturing processes affect the wrinkle resistance and pressing performance. Fabric crease recovery has been well investigated in the past. Based on the established understanding, blending wool fibres with stiff and resilient fibres, heavy weight fabrics, long float weave structure and finishing operations (e.g. crabbing, scouring, etc.) for reducing fibre-to-fibre and yarn-to-yarn friction should improve the fabric crease recovery. On the other hand, there is a lack of understanding of the effects of fabric properties and manufacturing processes on the pressing performance. The limited analysis in this study showed that increasing fabric relaxation shrinkage can improve the fabric pressing performance. Further work in this area is needed. References Biglia, U., Roczniok, A.F., Fassina, C. and Ly, N.G. (1991), ``The prediction of garment appearance from measured fabric properties'', in Stylios, G. (Ed.), Textile Objective Measurement and Automation in Garment Manufacture, Ellis Horwood. Chapman, B.M. (1974), ``A model for the crease recovery of fabrics'', Tex. Res. J., Vol. 44 No. 7, July, pp. 531-8. De Boos, A.G. (1987), Conflicting Requirements of Wool Setting for the Finisher and Tailor, Report No. G61, CSIRO Division of Textile Industry, July. Leung, M.Y. (2000), ``Objectively measured fabric requirements for production of high quality outerwear clothing'', PhD Thesis, The Hong Kong Polytechnic University.
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International Journal of Clothing Science and Technology
ISSN 0955-6222 Volume 13 Number 6 2001
International Textile and Clothing Research Register Editor-in-Chief George K. Stylios Paper format International Journal of Clothing Science and Technology includes six issues in traditional paper format. The contents of this issue are detailed below.
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Research index by institution_______________________ 111 Research index by country _________________________ 112 Research index by subject__________________________ 113 Research index by principal investigator ____________ 114 Note from the publisher ____________________________ 115
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CONTENTS
IJCST 13,6
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Editorial International Textile and Clothing Research Register: championing the research efforts of the community The International Textile and Clothing Research Register (ITCRR) is in its sixth year of publishing the research efforts of our community. It provides a breadth of activity in the field of textile and clothing research and it encourages participation and dissemination to those working in this discipline and further afield. Research, development and innovation can, without doubt, give us more wisdom, enable our industries to become more competitive, and contribute to our quality of life. I believe that registering research projects will provide the due credit to originators of the research and contribute much more to the future development of this field. Groups of expertise can be identified in this manner, repetition and re-invention can be avoided, leading to best utilisation of time and funding for faster and better directed research in the international arena, since globalisation is on everybody’s agenda. The ITCRR has been set up with all these things in mind. New and exciting research areas are being investigated by our community; the area of technical textiles is one where a lot of focus is directed at including the area of high performance clothing, wearable technology, intelligent/smart garments, etc. In these areas a lot of funds are being earmarked by private companies and government agencies producing encouraging and, in some cases, controversial, research results. New multi-million pound initiatives in the UK, such as the Faraday Parnership in Technical Textiles between the textile schools/departments of Heriot-Watt University, UMIST, the Univesity of Leeds and the British Textile Technology Group, are important landmarks for the future of textiles and clothing. IJCST has been set up as a platform for the promotion of scientific and technical research at an international level. With the statement that the manufacture of clothing in particular needs to change to more technologically advanced forms of manufacturing and retailing, IJCST will continue to support the community in these and other efforts. The journal will continue with its authoritative style to accredit original technical research, through refereeing all papers. IJCST will be instrumental in supporting conferences and meetings from around the world in its effort to promote the science and technology of clothing. Also, a forthcoming special issue of the Mount Fuji Conference in Japan, commemorating Professor Sueo Kawabata’s 70th birthday, is planned. © 2001 G. Stylios.
Editorial
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International Journal of Clothing Science and Technology, Vol. 13 No. 6, 2001, pp. 3-4 © MCB University Press, 0955-6222
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I praise the enthusiasm of our research community and those authors who have made IJCST an invaluable resource to all involved with textiles and clothing. I thank our editorial board for their continuous support and our colleagues who have acted in a refereeing capacity, with commitment to progress our research efforts. I take the liberty to list some of those names below (apologies in advance if anyone has accidentally been omitted from this list): Dr Norman Powell, University of Bradford Dr Taoruan Wan, University of Bradford Professor David Lloyd, University of Bradford Dr Jim Betts, University of Bradford Dr Steve Heycock, University of Bradford Dr Stephen Harlock, University of Leeds Dr G.A.V. Leaf, University of Leeds Dr David Brook, University of Leeds Professor Tim King, University of Leeds Dr C. Iype, University of Leeds Dr Jaffer Amirbayat, UMIST Dr David Tyler, Manchester Metropolitan University Dr Margot Baird, Heriot-Watt University Dr Jintu Fan, Hong Kong Polytechnic University Dr Lubas Hes, University of Minho Dr Jelka Gersak, University of Maribor Professor Paul Taylor, University of Hull Professor Haruki Imaoka, Nara Women’s University Professor Dick Horrocks, Bolton Institute of Technology Professor Mario De Araujo, University of Minho Professor H.J. Barndt, Philadelphia College of Textiles and Science Professor Sueo Kawabata, The University of Shiga Prefecture Professor Trevor J. Little, North Carolina State University Professor Masako Niwa, Nara Women’s University Professor Jachym Novak, Vysoka Skola Sronjni a Tectilffi Professor Isaac Porat, UMIST Professor Ron Postle, The University of New South Wales Professor Rosham Shishoo, Swedish Institute for Fibre and Polymer Research Professor Gordon Wray, Loughborough University of Technology Professor Witold Zurek, Lo & Technical University Thank you all, subscribers, authors, editorial board members, referees, publishing team, colleagues and students, for your support and note that my address for correspondence is: Heriot-Watt University, School of Textiles, Netherdale, Galashiels, Selkirkshire TD1 3HF, Scotland. George K. Stylios
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Research register
Research register
Belfast, UK Queens University, Belfast Dr B.K. Hinds, Dr J. McCartney, School of Mechanical and Process Engineering Research staff: Dr W. McLune, Mr B.L. Seow
An investigation into the fit and drape of garments Other partners: Academic None
Industrial Marks & Spencer, Coats Viyella, CDI Project ended: 29 February 2000
Project started: 1 March 1997 Finance/support: £183,000 Source of support: EPSRC Grant No. GR/L35638 Keywords: 3D, Fabric drape
The project aims to evaluate methods for specifying and modifying garment designs, modelled mathematically in a CAD system. A garment will have areas where fit is important whereas in other areas the shape will be determined by drape characteristics. A simulation of the overall appearance will be assessed and modified until the design is judged acceptable or otherwise. Major issues are the link between the density, material properties and the simulated shape, the scope of the user interface and the definition of the resulting patterns. Project aims and objectives •
To evolve a means of designing a garment as a 3D CAD model.
•
To introduce procedures for assessing fit and drape appearance given fabric characteristics.
•
To enable modification of initial design.
•
To determine resulting 2D patterns.
Academic deliverables •
Design of user interface for 3D garment CAD.
•
Knowledge of link between fabric characteristics and accuracy of simulation.
5
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Industrial deliverables • Basis for 3D CAD design systems Publication Gong, D.K. and Hinds, B.K. (1998), “Energy based drape modelling of fabric”, 3rd Biennial World Conference on Integrated Design and Process Technology, Berlin, 6-9 July.
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Belfast, UK Queens’ University, Belfast, Ashby Building, Stranmillis Road, Belfast BT9 5AH Tel: 0289 0 274147; Fax: 0289 0 661729 School of Mechanical & Manufacturing Engineering Dr J. McCartney, Dr B.K. Hinds Research staff: Dr B. Seow
Three dimensional design using fabric properties Other partners: Academic Industrial None Sara Lee Courtaulds Project started: 1 August 1999 Project ended: 31 July 2001 Finance/support: £135,008 Source of support: Sara Lee Courtaulds, IRTU Keywords: Performance fabrics, Fabric characteristics, Fabric modeling In common practice, the patterns for a newly designed garment are created by an experienced pattern technologist, made into a garment and worn by a standard model. This garment may be required to go through various alteration cycles until the fitting is deemed good. A range of sizes are then derived from these sample patterns. The entire process from concept garment to an approved set of patterns can take up to 12 weeks. This project aims to both improve and shorten the design process. A formula to predict the 3D behaviour of textile materials will be developed. The formula will then be incorporated in a computer-engineering model that predicts the 3D deformation of material under load conditions. A prototype garment CAD system developed at the end of this project will allow the user to design a garment on a 3D underlying body, automatically producing as its output the 2D shape of pattern of fabric necessary to give the 3D stress shape. This would both improve and shorten the design process. Details of research include devising mechanical testing equipment to determine new material characteristics that takes into account grain direction sensitivity. The test result is then used to validate the simulation model. This
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simulation model will then be tested on hybrid constructions such as seams and straps.
Research register
Project aims and objectives The objectives of the project are to characterise the behaviour of textile materials and to use this data in a computer-engineering model, which predicts the 3D deformation under load conditions. This will lead to the definition of 2D patterns necessary to give the 3D stressed shape. A prototype garment CAD system will be developed by the end of this project.
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Research deliverables (academic and industrial) • Bi-directional energy model for knitted fabrics. • Test device for model validation. • Prototype CAD system. Publications Not available.
Belgrade, Yugoslavia Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Yugoslavia Tel: 381 11 3370425; Fax: 381 11 3370425; E-mail:
[email protected] Professor Milanka Nikolic, Textile Engineering Department Research staff: Professor Srecko Nikolic, Professor Julijana Georgijevic, Tatjana Mihailovic, Ljiljana Simovic
Physical-mechanical phenomenon of woven and non-conventional materials Other partners: Academic None
Industrial Woollen fabric textile factory B. Krsmanovic, Paracin Project ends: December 2000
Project started: January 1996 Finance/support: N/A Source of support: Faculty of Technology at the University of Belgrade; Textile factory B. Krsmanovic, Paracin; National Fund for Science, Belgrade Keywords: Woven fabrics, Non-woven textiles, Mechanical characteristics, Elasticity, Anisotropy, Relaxation, Optimisation, Quality
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The basic idea of this project is in developing series of methods for monitoring structural parameters, as well as establishing their relation with the behavior of woven and non-woven materials. Establishing the connection among structural parameters of material (constructive elements, their position and distribution, construction) and their behavior during special conditions of usage, through monitoring the phenomenon of physical-mechanical characteristics and resistance mechanisms, contributes to establishing the relation for developing complex methodology of projecting textile surfaces. Investigation of textile complexes as porous and flexible systems represents the basis for establishing functional dependence “fibre-textile complex-final product” type. This is possible to achieve through the analysis of textile surface state and its topography, as well as constructive solutions and physical-mechanical characteristics. Analytic investigation of characteristics, such as flexibility and resistance to various strains, was conducted on woven fabrics and non-woven materials of various constructions aimed at establishing their basic models. The main focus is on mechanical characteristics, especially elastic properties under action of various loads (tensile, bending, pressure). Relaxation processes and recovery kinetics are particularly investigated. Making the connection between structure and mechanical characteristics enables the projection of the expected or desired behavior of woven fabrics. Besides, establishing criteria for estimation of the total elasticity, as the magnitude of quality index and its valorization, represents the possibility for establishing objective methods of woven and nonwoven materials of functional characteristics. Project aims and objectives The aim of the project is establishing the relations between parameters of woven as well as non-woven materials and their functional characteristics. Because of that, it was necessary to develop a series of methods for monitoring the physical-mechanical phenomenon of complex textile materials. The final aim is to establish optimal models of woven and non-woven textile surfaces, which are the base for projecting products of superior characteristics. The segment related to (an)isotropy of textile structures is particularly interesting. Data obtained on the basis of theoretic analyses and experimental measurements should contribute to acquainting one with the mechanisms of woven and non-woven materials’ behavior during their exploitation. Research deliverables (academic and industrial) Until now, results achieved are in conformity with formulated aims concerning the deepening of fundamental knowledge from the field of mechanics and physical-mechanical characteristics of woven and non-woven textile products. This is achieved by establishing optimal models from the aspect of elasticity and complex loading resistance mechanisms. The contribution of the investigation is in defining the physical-mechanical character of the phenomenon during usage
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and relaxation. The methodology of complex estimation, as the support for design of material and its characteristics, is particularly developed. Focus was on estimation of anisotropy, as well as realisation of isotropy materials. Results of this project are an integral part of quality estimation methodology. They will also serve for the advancement and optimisation of woven and non-woven fabric quality from the aspect of their functionality. Publications Annual reports. Many scientific articles in international textile journals (IJCST, Indian Textile Journal, Pakistan Textile Journal, Nuova Textil, etc.). National journal: Tekstilna industrija.
Bradford, UK University of Bradford, Bradford, UK Tel: +44 (0) 1274 384248; Fax: +44 (0) 1274 391333 Professor G. Stylios School of Textiles, Heriot-Watt University, Netherdale, Galashiels, Selkirkshire TD1 3HF, Scotland Research staff: Norman Powell Department of Industrial Technology, Textile and Garment Manufacturing System Engineering Group
Centre for objective measurement and innovation technologies (COMIT) for the textile clothing and retailing industries Other partners: Academic None
Industrial CBWT Bradford Council Project extended: December 2001
Project started: 1 January 1993 Finance/support: £2.8 million Source of support: ERDF (Retex 2 and Objective II) Keywords: Clothing, Garments, Retailing, Textiles
The objective of the centre is to provide measurement, testing and interpretation services to the textile, clothing and retailing industries, using the technologies resulting from many years of innovative research work, carried out at the University of Bradford. The unique systems employed measure fabric parameters objectively. These measurements are analyzed and interpreted to determine optimum
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manufacturing parameters to produce quality products for a competitive market. The project has recognised the importance of objectively quantifying products and processes, and their interpretation in a traditionally skills-oriented industry, where subjectivity hinders its future development. Technological innovations in which the group at COMIT has contributed in recent years have provided instrumentation measurement systems and procedures which can enable the industry to increase quality, added value, production efficiency, waste minimization and sustainability, to compete globally and penetrate newly emerging markets. To that effect COMIT is preparing our local industry to make best use of the technology, and it also feeds back industrial requirements to the EU committee. Project aims and objectives The promotion, standardization and implementation and training for the textile clothing and retailing industries, through objective measurement technologies, to improve competitiveness of the industry in the world market. To develop further and extend the services of COMIT to a large client base of SMEs within the textile clothing and retailing industries. Research deliverables (academic and industrial) COMIT has been extended into 2001; with this phase the scheme will incorporate new research in yarns and garments, which will enable the scheme to become coherent and more comprehensive. Through this initiative the centre has developed close working relationships with over 300 companies, providing training in objective measurement technologies, measurement and interpretation, development of fabric fingerprinting, prediction of optimum sewing conditions and fabric/garment aesthetics. Other activities of the centre include successful identification of a number of individual industrial projects which are currently under way and several successful industrial graduate placements have already taken place.
Dresden, Germany Technische Universität Dresden, 01062 Dresden, Germany Tel: +49 351 4658 371; Fax: +49 351 4658 361; E-mail:
[email protected] [email protected],
[email protected] Institute of Textile and Clothing Technology, Chair of Clothing Technology, Prof. Dr-Ing. Habil Rödel Dr-Ing. A. Schenk, Dr-Ing. S. Krzywinski
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Simulation of drape behaviour of fabrics Other partners: Academic Industrial Textilforschungsinstitut ThüringenNone Vogtland e. V. Greiz, Germany Project started: 1 July 1997 Project ended: 30 June 2000 Finance/support: DM300,000 Source of support: German Research Foundation Keywords: CAD, Drape, Mechanical properties, Simulation, 3D In the textile and clothing industries, because of the increasingly individual and customer-oriented production, the sample collections of the firms extend more and more, whereas the quantities for the production decrease. At present, the stage of product development and product preparation of clothes requires approximately three times the stage of consumption. In order to compensate for the resulting greater efforts in the product preparation and to react more quickly and flexibly to latest fashion, the use of complex CAD-CAM solutions is a must. With CAD-systems available on the market (with two exceptions) the systems work only two-dimensionally and the material behaviour and the material parameters are not taken into account. Both these aspects are required for the three-dimensional display of a model with regard to the draping, in order to give the designer and model maker a real impression of the model. The main focus of this research is to investigate the fundamentals of three-dimensional handling of fabrics. For that, a prerequisite is the implementation of algorithms for the simulation of draping of ready-made clothes. In this project a model will be presented for the calculation by approximation of a drape test standardized in the textile industry. As woven fabric is of low thickness compared with the other dimensions, the fabric can be considered to be a two-dimensional continuum. For the simulation model, the shell theory is taken as a basis. The significant material parameters must be taken into consideration. Therefore, the more detailed treatment of physical and mechanical properties and their correct mathematical and physical formulation is of interest. Investigations concern several technical and technological parameters of woven fabrics, mainly the influence of the finishing process on the mechanical properties of the fabrics. Project aims and objectives It is the aim of this project to describe and simulate the deformation behaviour of flexural fabrics (especially of woven fabrics). Therefore a lot of experimental results with various woven fabrics are necessary. The deformation theory developed in the Institute of Mechanics of Solids at the Dresden University of Technology and its application for fabrics is utilized as a practicable approach for the simulation of the drape behaviour. In the frame of this research we try to
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improve the obtained results by means of a better approach with the consideration of orthotropic material behaviour and additional strains. Investigations into the description of the material behaviour and of its properties mainly in dependence on the finishing processes are a further necessary focal point.
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Research deliverables (academic and industrial) The three-dimensional display of a two-dimensional pattern construction on a dummy or vice versa, a development of a three-dimensionally constructed model into the two-dimensional level, would be the optimal possibilities to examine the correct fitting and the form of a model, when the specific material parameters are taken into account. Publications Brummund, J., Schenk, A. and Ulbrich, V. (1998), “Beitrag zur Modellierung des Fallverhaltens in der Textilindustrie”, Proceedings GAMM, Bremen, Germany. Fischer, P. (1997), “Ermittlung der mechanischen Kenngrößen textiler Flächen zur Modellierung des Fallverhaltens unter Berücksichtigung konstruktiver, faserstoffbedingter und technologischer Abhängigkeiten”, Dissertation, TU Dresden, Fakultät Maschinenwesen. Rödel, H., Ulbricht, V., Krzywinski, S., Schenk, A. and Fischer, P. (1997), “Simulation of drape behaviour of fabrics”, Conference Proceedings, Advances in Fibre and Textile Science and Technologies, Mulhouse. Schenk, A. (1996), “Berechnung des Faltenwurfs textiler Flächengebilde”, TU Dresden, Dissertation.
Dresden, Germany Technische Universität Dresden, 01062 Dresden, Germany Tel: +49 351 4658 358; Fax: +49 351 4658 361; E-mail:
[email protected];
[email protected] Institute of Textile and Clothing Technology, Chair of Clothing Technology, Prof. Dr-Ing. Habil Rödel Ms. Dipl.-Ing. Elke Haase and Mr. Dr. sc. nat. Rolf Bochmann
Fundamental investigations for construction of compressive clothing and its effect on blood circulation Other partners: Academic Industrial Technische Universität Dresden None Faculty of Medicine Prof. Dr. med. A. Deussen Project started: September 1999 Project ended: November 2001 Finance/support: DM100,000 Source of support: German Research Foundation Keywords: Knitwear, Medical textiles, Physiology
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The product quality of cloths depends not only on the physiological comfort. Also the mechanical impact could be of interest. One aim of the research project is the determination of the pressure and comfort requirements to induce the shape effect on the body. Another aim could be the improvement of the blood circulation. The blood circulation has a great influence of the capacity, productivity and health of the customer. Not enough work was done on the performance deterioration of the pressure garments in terms of blood circulation. This project initiates an integrative approach to analyze the relationships between the material parameters, the pattern construction and the biological impact. Until now there have been no functional methods that consider defined material parameters in pattern construction. Project aims and objectives • investigations of the mechanical impact of pressure garments on the body with consideration of the material behaviors, the pattern construction and motion studies; • develop an objective measurement equipment to analyze the pressure on the surface of the body to define optimum range of pressure; • quantification of the blood circulation with a focus on the arms and legs due to a pressure garment; • optimize the production process of knitted fabrics with manufacturing engineering. Research deliverables (academic and industrial) Deliverables include research and conference papers , product collections, exhibitions and knowledge base. Publications None
Karachi, Pakistan University of Karachi, Department of Applied Chemistry, Karachi 752270 Tel: 4534663-4; Fax: 92-21-4525881; E-mail:
[email protected];
[email protected] Prof. Dr Syed Ishrat Ali Research staff: Zaheer Ahmad Chughtaee
Studies on the effects of polymeric plasticizers in PVC coating formulations
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Other partners: Academic Industrial Faculty of Science, University of Preston University of Pakistan Karachi Project started: June 1998 Project ended: June 2000 Finance/support: Rs.1 million Source of support: Preston University of Pakistan Keywords: Coatings, Plastics, Thermals Polyvinyl chloride is a versatile plastic material. Very rigid, hard and tough products are manufactured without the addition of any plasticizers while flexible products are made with variety of plasticizers, consisting of phthalates, aliphatic mono and dibasic acid esters, aromatic tri-carboxylic acid esters, aliphatic alcohol esters of phosphoric acid. Every plasticizer has its own characteristics and does not have a wide range of properties. The main points to be considered are cost, migration, mar resistance, low temperature flexibility, longer service life, better thermal properties. To achieve these properties the polymeric plasticizers are incorporated in PVC formulations. The performance characteristics are improved with the use of polymeric plasticizers. The quality parameters include rheology, viscosity and flexibility of the coated materials. Description and quality control tests and equipment will be used to prove the above characteristics according to the international standards. Workplan PVC resin, heat stabilizers, fillers will be compounded by mixing phthalates, epoxy plasticizers along with polymeric plasticizers in a stainless steel cylindrical vessel using a light speed shearing mixer. The product is called plastisol. Application will be carried out by spraying, spread coating, screen printing on the substrate. Curing will be done in a variable temperature oven at 160-170˚C for a specific time period. The sample will be tested according to ASTM, DIN, ISO standards for migration, mar resistance and low temperature flexibility. Aims of present study (1) Survey and selection of suitable polymeric plasticizers from aliphatic, aromatic and polyurethane plasticizers. (2) Prepare workable compounding formulation for plastisol by changing the ratio of plasticizers. (3) Find the uses of best coating formulations for value added and export oriented products to earn foreign exchange. (4) Industrial applications of these coatings to save foreign exchange. Project aims and objectives (1) Survey and selection of suitable polymeric plasticizers from aliphatic, aromatic and polyurethane plasticizers.
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(2) Prepare workable compounding formulation for plastisol by changing the ratio of plasticizers. (3) Find the uses of best coating formulation for value added and export oriented products to earn foreign exchange. (4) Industrial applications of these coatings to save foreign exchange.
Research register
Industrial deliverables (1) Industrial production of PVC plastisol for the Pakistan and overseas market.
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Kaunas, Lithuania Kaunas University of Technology, Faculty of Design and Technologies, Studentu str. 56, Kaunas-3031, Lithuania Tel: 370-7-767066; Fax: 370-7-353989; E-mail:
[email protected] Hab. Dr. Professor Matas Gutauskas Research staff: Dr L. Papreckiene, Dr V. Masteikaiste, doctoral students V. Daukantiene and E. Strazdiene
Behavior evaluation and prognosis of textile and polymer material shells Other partners: Academic Industrial None None Project started: January 1997 Project ends: January 2002 Keywords: Deformation, Membrane, Polyethylene, Punch, Shell, Structure, Textile, X-ray diffraction The research deals with the specific area of materials science concerning clothing, packing and other heterogenic structures of polymer materials. The investigation is aimed to determine parameters of textile and other polymer materials behavior evaluation in biaxial deformation and to develop basis for its diagnosis and prognosis taking into account ambient conditions and acting loads of materials serve and processing. The investigation deals with the problem concerning the measurement and theoretical description of spatial shape of textile or polymer material shell obtained by various biaxial deformation methods. Besides, the investigation of interrelations between these biaxial deformations is to be carried on and the search for new methods and regimes of thin anisotropic polymer membrane formation will be made. Thus, the research seeks to define the relationship between acting loads, materials anisotropy, formed shell geometric parameters
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and resulting strains. The effect of textile material structure upon its spatial behavior is going to be examined, also. In addition, the assessment of friction factor between textile or polymer shell surface and deforming device will be given. Project aims and objectives A universal and comfortable experimental base for membrane and punch deformation tests must be created which will make it possible to investigate the behavior of different structure materials, i.e. membrane, woven or knitted materials and to reveal characteristic regularities of such processes and materials. Research deliverables (academic and industrial) The new experimental base of textile and polymer materials biaxial deformation is going to extend the existing laboratory of material testing and will be used in the study process of the University. Theoretical results of this research work will deepen the knowledge of materials spatial shape formation and will be used in textile and polymer garments design process. Publications Daukantiene, V. and Gutauskas, M. (1997), “The influence of clamp geometry on polymer membrane punch deformation characteristics”, Proc. of the Cone Design and Technology of Consumer Goods, Kaunas, pp. 201-5 (in Lithuanian). Daukantiene, V. and Gutauskas, M. (in press), “The performance in secondary structures of polyethylene membranes after uni/biaxial deformation process”, Materials Science, Kaunas. Masteikaite, V. and Gutauskas, M. (1997), “Mechanical stability of fused textile systems”, International Journal of Clothing Science and Technology, Vol. 9 No. 5, pp. 360-6. Strazdiene, E., Daukantiene, V. and Gutauskas, M. (in press), “The changes of polyethylene structure in shell forming process”, Materials Engineering, Kaunas. Strazdiene, E., Gutauskas, M. and Williams, J.T. (1997), “Mechanical behavior prediction of spatial textile constructions”, Proc. 2nd International IMCEP’97 Conference, Maribor, Slovenia, pp. 71-9. Strazdiene, E., Gutauskas, M., Papreckiene, L. and Williams, J.T. (1997), “The behavior of textile membranes in punch deformation process”, Materials Science, Kaunas, Vol. 2 No. 5, pp. 50-4. Tijuneliene, L. and Gutauskas, M. (1998), “The geometry of punch formed thin shell and method of its determination”, Proc. of the Cone Design and Technology of Consumer Goods, Kaunas, pp. 194-200 (in Lithuanian). Tijuneliene, L., Strazdiene, E. and Gutauskas, M. (in press), “The behavior of polyethylene membrane due to punch deformation process”, Polymer Testing, Elsevier, Oxford.
Kaunas, Lithuania Kaunas University of Technology, Faculty of Design and Technologies, Studentu str. 56, Kaunas-3031, Lithuania Tel: 370-7-767066; Fax: 370-7-353989; E-mail:
[email protected]
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Department of Clothing and Polymer Products Technology Hab. Dr. Professor Matas Gutauskas Research staff: Dr E. Strazdiene, Dr L. Papreckiene, Dr V. Daukantiene and master student G. Martisiute
New method of textile hand evaluation Other partners: Academic Industrial None None Project started: June 2001 Project ends: December 2004 Keywords: Textiles, Membrane, Pulling through, Biaxial deformation, Geometry, Wave, Jamming Although a large part of textiles is concerned with imparting desirable physical properties, theoretical understanding of the effect of these properties on material response is limited. The research project will provide new method for the evaluation of planar anisotropic material’s behaviour and original experimental information will be obtained, contributing to the existing knowledge in the field of mechanics of heterogenic, e.g. textile structures. New pulling through a hole method is similar to a well-known punch test used to control strength parameters of knitted material. The difference is that rounded specimen is not firmly fixed by its external contour and the diameter of the hole and the punch are relatively small compared to that of the specimen. Latest investigations have shown that this method is sufficiently informative and able to characterise such hand properties as softness, slippery, roughness, etc. Besides, it provides useful information for the evaluation of textile’s drape and anisotropy. Project aims and objectives The aim of the research is to set the relationship between the geometry and resistance parameters of textile membrane due to its type and testing conditions. Tests are performed by the original device mountable on the standard tensile testing machine. It consists of two perpendicular plates, replaceable stand with the hole in the centre and supporting plate with the hole of the same radius. Spherical punch is used to pull rounded specimen through the hole of the stand. The investigations are realised by two pulling through cases: free pulling through the hole of the stand; restrained pulling simultaneously through the limited crack of the plate and through the same hole of the stand. Research deliverables (academic and industrial) New testing method for textile and its experimental base will extend the existing laboratory of material testing and will be used in the study process of the Kaunas University of Technology. Theoretical results of this research will
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deepen the knowledge of textile spatial shape formation and will be used in textile and polymer garments design process. Publications Martisiute, G. and Gutauskas, M. (in press), New Approach to the Evaluation of Fabric Handle, Materials Science, Kaunas.
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Martisiute, G. and Gutauskas, M. (in press), “Pulling through process of knitted membrane: analysis of geometry”, Proc. of the Conf. Design and Technology of Consumer Goods – 2001, Kaunas (in Lithuanian). Strazdiene, E., Martisiute, G., Gutauskas, M. and Papreckiene, L. (in press), “New method for the objective evaluation of textile hand”, Journal of the Textile Institute, UK.
Kettering, UK Satra Technology Centre, Satra House, Rockingham Road, Kettering, Northamptonshire NN16 9JH Andrea Wilford, CTC
Clothing comfort (intended) Other partners: Academic None Project started: – Finance/support: N/A Source of support: SATRA Keywords: Clothing, Design • •
•
Industrial None Project ends: ongoing
A study of the factors important for comfortable clothing and development of a method to measure and assess comfort. To provide the clothing industry with a practical technique to quantify the comfort of clothing, highlighting strengths and weaknesses in design and making recommendations on how to improve the comfort of the garment. To provide guidance in product design, product manufacture and purchasing.
Project aims and objectives The development of a Clothing Comfort Index. A study of the factors important for comfortable clothing and to develop a practical technique for the quantification of clothing comfort. Academic deliverables Production of a Comfort Index System.
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Industrial deliverables A design guide for manufacturers and retailers to enable them to source materials and provide goods which meet consumer needs.
Research register
Publication SATRA, “Clothing-Closeup”.
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Kettering, UK Satra Technology Centre, Satra House, Rockingham Road, Kettering, Northamptonshire NN16 9JH Austin Simmons, CTC Research staff: Mark Gamble
Swimwear degradations Other partners: Academic None Project started: June 1998 Finance/support: N/A Source of support: SATRA Keywords: Elastane, Swimwear
Industrial None Project ends: ongoing
Limited wear trials were conducted on a variety of elastane-containing swimwear and examinations were carried out on a selection of failed swimwear garments. The common feature of each garment’s failure was the breakdown of the elastane component. In each case of failure it was noted that garments exhibited a particular pattern of wear. The project currently being undertaken aims to reproduce the wear patterns in a laboratory setting. It is intended to investigate the flow of swimming bath water through the fabric structure of different garments and the effect of flow restriction in preserving the life of a garment. It is also intended to develop a test rig for assessing the effects of combined chemical and mechanical action on swimwear garments. Project aims and objectives To establish an effective means of assessing the likely wear performance of elastane-containing swimwear. The means of assessment to incorporate a chemical and mechanical system for degrading swimwear materials. Academic deliverables An understanding of the mechanisms which contribute to elastane failure in swimwear garments.
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Industrial deliverables A test apparatus for predicting garment performance. Publication SATRA, “Clothing-Closeup”.
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Kettering, UK Satra Technology Centre, Satra House, Rockingham Road, Kettering, Northamptonshire NN16 9JH Andrea Wilford, CTC Research staff: David McKeown, Mark Gamble
Water-resistant permeable membranes Other partners: Academic None Project started: – Finance/support: N/A Source of support: SATRA Keywords: Garments, Wear
Industrial None Project ends: ongoing
Limited wear trials have been undertaken on a series of commercially available garments which incorporate membrane structures. The results of this testing, which may be advanced to moisture and temperature recording of wear trialled products, using data-loggers, will be made available to SATRA members. Much of the work that is to be undertaken will complement SATRA’s current Comfort Index work. Project aims and objectives To understand the mechanisms at work in water permeable membranes which are used for clothing. We aim to draw on the expertise developed in the use of such materials in footwear. Academic deliverables To develop performance guidelines for current market products. Industrial deliverables To provide a service to industry for the development of membrane materials (and their testing). Publication SATRA, “Clothing-Closeup”.
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Kowloon, Hong Kong Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Tel: (852) 2766 6485; Fax: (852) 2773 1432 C.K. Chan and G. Taylor Research staff: C.Y.B. Tsang-Ng
Kinanthropometry and somatotyping study of the physique of Hong Kong-Chinese disciplined personnel Other partners: Academic Industrial None None Project started: 2 January 1997 Project ended: 1 January 2000 Finance/support: N/A Source of support: Hong Kong Polytechnic University Keywords: Physique, Uniforms The uniformed forces in Hong Kong comprise a variety of “streams” like the Police, Correctional, Fire Services, Immigration, Customs & Excise Departments. They can be classified as a homogeneous group. The physical requirements are vague for clear classification of the physique of the uniformed forces. No study or reference of the general body shape of the uniformed recruits has ever been set. The lack of an accurate category for defining the required body configuration for each of these uniformed forces caused difficulties in setting up a standard scale of body measurements in the manufacturing of suitable fitting uniforms in the past. From the standpoint of the clothing field as well as with consideration of the physiology and psychology of these personnel, it would be worthwhile to develop a united and measurable standard based on kinanthropometry study and somatotyping analysis. Kinanthropometry is defined as the study of human size, shape, proportion, composition, maturation and gross function, in order to understand growth, exercise, performance and nutrition. It is similar to the mechanistic approach to human motion, i.e. anthropometry. However, the study of anthropometry is confined to width, length and girth measurements, rather than changes that occur in the human physique as a result of physical training. Somatotyping provides classification of the human body shape into three basic types: ectomorph, mesomorph and endomorph. Hence, through the application of kinanthropometry together with somatotyping in the study of the human physique, the clothing industry can improve traditional sizing systems by means of reference to the structure and function of the human body.
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Project aims and objectives Of prime importance will be to study: •
The relationship of the kinanthropometry and somatotypes of the recruited personnel of the chosen uniformed force.
•
The relationship among the designed anthropometric parameters.
•
The adaptability of the obtained data into quantified body measurement for establishing a sizing system in the clothing industry.
Academic deliverables The applied and theoretical research in the field of kinanthropometry, somatotyping and anthropometry for the clothing manufacturing industry as well as in other disciplines. Industrial deliverables The results from the project would help to streamline the existing uniform sizing system for the uniformed forces as well as upgrading in the efficiency of both human physiology and psychology of the police personnel due to the improvement in the comfort of wearing the uniforms. Publications “Application of kinanthropometry and somatotyping to the study of the physique of Hong KongChinese disciplined personnel” (1997), HKITA, pp. 149-61, November. “Application of kinanthropometry and somatotyping to the study of the physique of Hong Kong Chinese disciplined personnel, Part I” (1997), FAPTA. “Application of kinanthropometry to the study of Hong Kong-Chinese disciplined personnel” (1998), Proceedings of ERGON-AXIA ’98 Conference, pp. 247-50. “Application of kinanthropometry to the study of the physique of Hong Kong-Chinese disciplined personnel” (1998), Proceedings of the China and Hong Kong Textiles Joint Conference, edited by China Textiles Engineering Society and Hong Kong Institution of Textiles and Apparel, China Textiles Engineering Society, Beijing, pp. 133-8. “Kinanthropometry study of Hong Kong-Chinese disciplined personnel (recruits)” (1997), Proceedings of the 1st International Scientific Conference, “Kinesology. The present and the future”, Dubrovnik, Croatia, pp. 242-4. “Kinanthropometry study of the physique of Hong Kong-Chinese correctional services recruits” (1998), Proceedings of International Conference TEXTILESCIENCE 1998, Czech Republic, pp. 477-80.
Kowloon, Hong Kong Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Tel: (852) 2766 6506; Fax: (852) 2773 1432; E-mail: tcrs/
[email protected] Dr Zhang Zhi-ming, C.S. Leung Research staff: Law Ka Ming and Mr Derry
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The influences of fashion changes on the apparel-buying behaviour of young generation in Hong Kong Other partners: Academic Industrial None None Project started: 4 May 1998 Project ended: 3 May 2000 Source of support: Hong Kong Polytechnic University Keywords: Clothing industry, Consumer behaviour, Fashion, Japan, Retailing, Social systems To most of the people in a society, fashion change represents change in style for a certain period of time. However, the influence of fashion change is different in different age groups. Young people have higher response when compared with people in other stages of life. Studies showed that there are different types of change agents of fashion. Change agents refer to people, social system or others, which influence the acceptance of new fashion. In this project, the individual, industrial and cultural perspectives will be studied. Individual perspective includes clothing satisfaction, fashion involvement, segmentation of different fashion groups among Hong Kong young people and the social psychological approach between fashion change. Industrial perspective concerns the influence of different parties in the fashion system, which include retailers and designers. From the interviews with professionals in Applied Social and Japanese Studies, family, peer and the influence of Japanese fashion can shape the concept of fashion in the minds of young people. Hence, those areas will be investigated under the cultural perspective. To know the degree of influences between different factors is meaningful in terms of design and promotion campaign, especially for clothing retailers targeting young people as their potential customers. Project aims and objectives • To obtain spending patterns of clothing among young people in Hong Kong. • To investigate the frameworks affecting fashion change from the viewpoint of consumers and fashion industry in Hong Kong. • To determine the degree of fashion leadership within the Hong Kong young generation. • To determine the influences of family, peer group culture and the fashion of other countries to the studied sample. Academic deliverables To determine the influences of fashion change frameworks on Chinese Hong Kong young people with reference to the unique culture of Hong Kong society.
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Industrial deliverables To suggest ways in style design, retailing strategies toward the studied groups based on the findings. Publications Law, K.M., Zhang, Z.M. and Leung, C.S. (1999a), “Fashion change”, Textile Asia, February, pp. 30-1. Law, K.M., Zhang, Z.M. and Leung, C.S. (1999b), “An investigation of fashion change and the apparel-buying behaviour of Hong Kong young generation: the background and preliminary work”, Research Journal of Textiles and Apparel. Law, K.M., Zhang, Z.M. and Leung, C.S. (1999c), “Fashion leadership among Hong Kong young generation”, Conference paper for the 2nd International Textile and Apparel Conference.
Kowloon, Hong Kong The Hong Kong Polytechnic University, Yuk Choi Road, Hung Hom, Kowloon, Hong Kong Tel: 852-27666525; Fax: 852-27731432; E-mail:
[email protected] Dr Winnie Yu, Professor Edward Newton, Institute of Textiles and Clothing, Apparel Research Laboratory Research staff: Miss Cherie Chan
Conceptual model of intimate apparel design Other partners: Academic Industrial None Sunikorn Knitters Limited Project started: 19 October 1999 Project ends: 18 October 2001 Finance/support: $995,700 Source of support: Area of Strategic Development Fund Keywords: Conceptual model, Intimate apparel, Lingerie, Design, Process The goal of any conceptual design of garment is to add value. There is an increasing interest in using hi-tech fiber, functional fabric, seamless construction, new color, trimmings, fasteners and special fit. The introduction of new design into ladies’ intimate apparel becomes more fashion-oriented. However, companies always find difficulty in recruiting qualified and experienced designers. It takes excessive time to train the new blood, with lots of trials and errors. Intimate apparel is so complex that it requires multifunctions of comfort, stretch, shaping, protection, support and durability as well as aesthetic match with the outer-garments, at a moderate price. No systematic model is available in the industry for the designers to handle the necessary information such as material cost, product trend, consumer needs and market change for their commercial design.
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This project proposes to develop a conceptual model for intimate apparel design, with an overall aim of providing an intelligent system for making creative design with practical concerns. As a consequence, a company can take advantage of reducing the developing cost by using a conceptual model and well-structured information system for intimate apparel design.
Research register
Project aims and objectives This project is proposed to achieve four specific objectives as follows: (1) to examine the existing concepts, information flow, technical process and working methods in designing intimate fashion; (2) to build up an architecture for intelligent support of intimate apparel design with knowledge database; (3) to rationalize the process of commercial design including fashion inspiration, sketching, color mix, material selection, fabric testing, pattern cutting, sample fitting, sizing and product engineering; and (4) to develop and test the effectiveness of a new integrative conceptual model for intimate apparel design.
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Research deliverables (academic and industrial) Conference paper, research paper, model for intimate apparel design. Publications Chan, Y.C., Yu, W.M. and Newton, E. (2000a), “A discussion on bra inventions”, Journal of Fashion Marketing and Management, June. Chan, Y.C., Yu, W.M. and Newton, E. (2000b), “Evaluation and analysis of bra design”, Journal of Fashion Marketing and Management, October.
Kowloon, Hong Kong The Hong Kong Polytechnic University, Yuk Choi Road, Hung Hom, Kowloon, Hong Kong Tel: 852-27666525; Fax: 852-27731432; E-mail:
[email protected] Dr Winnie Yu, Dr Roger Ng, Institute of Textiles and Clothing, Apparel Research Laboratory Research staff: Mr Sunny Yan, Mr Wilson Lui, Rapid Product Prototyping Syndicate, Ms Sandy To, Ultra Precision Machining Centre
Advancement of moiré body scanner and 3D visualization Other partners: Academic East China University
Industrial Jeanswest International
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Project started: 15 March 2000 Project ends: 31 January 2001 Finance/support: $1,997,000 Source of support: Industrial Guided Applied Research & Development Keywords: Body scanner, Moiré topography, Visualization, 3D, Pattern
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The project is divided into four phases. Phase 1: Enhancement and commercialization of single moiré scanner A single moiré scanner for capturing the human leg has been developed in our laboratory. To commercialize this novel product, the hardware will be packaged with an attractive design of housing, integrated with all optical components. The software program will be enhanced in accuracy and speed. The hardware is tested extensively to check if optical/mechanical refinement is required. The practical needs in the industry will be investigated through market survey and tests on various human figures. Then an attempt will be made to commercialize it based on market needs. Phase 2: Optical advancement of moiré topography Based on our experience, further research can be made on optical advancement to increase the moiré fringe visibility. The work includes a feasibility test of using flash light, optimization of the grid pitch, increase of CCD resolution, using macro design lens, installation of film cartridge at focal plane, enlarging the scanning format, improvement of hardware mechanism, and making even light brightness. Phase 3: Development and commercialization of a multi-head body scanner In this stage, an advanced version of multi-head body scanner will be developed. Light is projected through high density grid on to the body by flash tubes for quick shots. The images can be simultaneously transferred into a computer for fringe analysis. The 3D data are then used to map a body surface and the required body dimensions will be extracted by computer program. Phase 4: Visualization of 3D human body A software program will be developed to perform the following tasks: •
generate virtual human body using the 3D data cloud;
•
project a virtual garment on the virtual mannequin;
•
project texture on to the virtual garment;
•
display the 3D images on the monitor; and
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produce garment patterns based on built-in procedure or using 3D pattern mapping method.
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Project aims and objectives It is aimed to design and develop several sets of single-head and multi-head body scanner with six “S” features – small, slim, saving, swift, simple, and safe. The specific objectives are: •
to enhance the optical system of moiré topography;
•
to improve the image processing;
•
to provide a quick and realistic visualization of captured image; and
•
to develop and commercialize the body scanner.
Research deliverables (academic and industrial) Upon completion of this project, the following deliverables will be provided: •
An innovative design of half body scanner made with six “S” features – small, slim, saving, swift, simple and safe.
•
Professional service to the clothing industry regarding body scanning and its related applications.
•
Optical advancement of moiré topography that contributes a low-cost method for non-contact measurement which can be used for body shape analysis, evaluation of clothing appearance and garment fit.
•
Semi-automatic/automatic moiré image analysis system.
•
3D visualization of captured image for better product development and adding value to apparel retailing.
Patent to be filed •
New optical design of moiré camera with wide coverage, short image capturing and high resolution in short distance.
•
New photographic chemical process to obtain high-density range and high transparency for photographic grid plane.
Publications Gu, H., Yu, W.M., Yan, S., Ng, K. and Hu, J. (2000), “Image improvement and fringe analysis of a moiré body measurement system”, World Automation Congress, 3rd International Symposium on Intelligent Automation and Control, Maui, Hawaii, June 11-16, Article number ISIAC048, ISBN: 1-889335-10-Xn. Yu, W.M. (1999a), “3D body scan – a new measure of size and shape”, ATA Journal, October/November, pp. 69-70. Yu, W.M. (1999b), “3D body scanning and custom-fit apparel”, Journal of Textile Research, Vol. 3, pp. 156-9. Yu, W.M. (2000), “Fit evaluation of men’s jacket using moiré topography”, Textile & Clothing, Vol. 12 No. 2, March. Yu, W.M., Yan, S. and Gu, H.B. (1999), “Design of 3D body scanner for apparel fit”, Proceedings of the 5th Asian Textile Conference, September, pp. 400-3.
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Kowloon, Hong Kong The Hong Kong Polytechnic University, Yuk Choi Road, Hung Hom, Kowloon, Hong Kong Tel: 852-27666525; Fax: 852-27731432; E-mail:
[email protected] Dr Winnie Yu, Professor Xiao-ming Tao, Dr Jin-tu Fan, Dr Zhi-min Zhang, Institute of Textiles and Clothing, Apparel Research Laboratory Research staff: Mr Xiao-ming Qian, Ms Xiao-ning Jiao
Product innovation of comfort stretch/pressure garment Other partners: Academic Industrial Jockey Club Rehabilitation Triumph International Engineering Centre Project started: 1 January 2000 Project ends: 31 December 2001 Finance/support: $995,700 Source of support: Area of Strategic Development Fund Keywords: Comfort, Stretch garment, Pressure, Sensory, Shape The effect of body shape on the wearing pressure was seldom studied. There is a lack of understanding of the optimum range of pressure distribution, stationary and dynamically, for different types of products, body sizes and shapes, as well as different ages of consumers. No work was made on the performance deterioration of the pressure garments in terms of shaping power and comfort after repeated use. This project initiates an integrative approach to study the consumer market of the pressure foundation garment, the existing product limitation and the actual functional requirement for different body shape. These will then be transferred to the ideas for fabric, pattern and production design. The product quality will then be evaluated in terms of sensory comfort, static and dynamic pressure, shape-up effect and wearing performance. Project aims and objectives This project proposes to develop a comfortable and high performance foundation garment that provides adequate pressure distribution to achieve good appearance and body feel. Specific aims are to: • analyse the customer needs and market potentials; • examine the functional performance of selected pressure foundation wear during wear; • identify the functional requirements and problems;
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develop a model to test and redesign the warp knit fabric’s performance in providing optimal pressure and extensibility; analyse the human body shapes with a focus at the waist to abdomen segment; determine the pressure and comfort requirement to induce the desirable shape-up effect on the body; design the fashion style and pattern to achieve desirable body comfort and shaping functions; develop an objective system to evaluate the overall function of pressure, body shape and wear comfort; and optimise the production process with manufacturing engineering.
Research deliverables (academic and industrial) Deliverables include review papers, research papers, conference papers, register patents for pressure analysis instruments, product collections, exhibitions and knowledge base. Publication Yu, W.M. (2000), “Special functions and market potential of intimate apparel”, ATA Journal, October/November.
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: (053) 810 2536; Fax: (053) 812 5702; E-mail:
[email protected] Seung Jin Kim, Textile Processing Lab.
A study of optimum production condition for the development of the composite yarns and fabrics for the natural/PET garment Other partners: Academic Industrial None None Project started: 1 March 1999 Project ended: 28 February 2000 Finance/support: US$33,000 Source of support: RRC Keywords: 2-for-1 twister, Composite twister, Elastic recovery, Thermal stress, Weaving preparatory, Winder
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The objectives of this project are to develop attachment of weaving preparatory machinery such as 2-for-1 twister, winder, yarn texturing machinery, twister and composite twister for developing the composite yarns and fabrics for natural/PET garment. In addition, the optimum processing conditions such as yarn tension, guide position, over feed and yarn feed speed are surveyed with various natural/PET composites yarns such as Viscose/PET, Cotton/PET, Rayon/PET, Wool/PET and Acryl/PET. Also the various physical properties of the composite yarns such as thermal shrinkage, thermal stress, tensile modulus, yarn bulkiness and elastic recovery are measured and discussed with various processing conditions. Using these yarns, fabrics are made and their physical properties are measured and discussed with various yarn properties. Project aims and objectives This project is aiming to develop attachment for 2-for-1 twister, winder, yarn texturing machine, ordinary twister and composite twister for composite yarns, and optimum processing conditions are decided for these weaving preparatory machines.
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: (053) 810 2536; Fax: (053) 812 5702; E-mail:
[email protected] Seung Jin Kim, Textile Processing Lab.
A study of optimum production condition for the development of the PET composite yarn for knitted fabrics Other partners: Academic Industrial None None Project started: 1 March 1999 Project ended: 28 February 2000 Finance/support: US$12,000 Source of support: RRC Keywords: Bulkiness, PET/Acryl, PET composites yarns, PET/Rayon, Pre-twister This project is aiming to develop knitted yarns and fabrics using PET composites yarns such as PET/Acryl, PET/Acetate, PET/Rayon and PET/Natural yarns.
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This project includes development of optimum production condition on the composite yarn manufacturing machineries such as pre-twist texturing machine and blend twisting machine of two or three folded yarns. Using these yarns, knitted fabrics are made and the bulkiness of knitted fabrics is measured and discussed; with various knitted yarns, optimum knitted yarn manufacturing conditions are decided. Project aims and objectives The objective of this project is to develop knitted yarns and fabrics of PET/PET, PET/Acryl, PET/Acetate, PET/Rayon and PET/Natural yarns using pre-twist texturing machinery. The optimum production conditions for the best knitted fabrics are decided and discussed with various knitted yarns.
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: (053) 810 2536; Fax: (053) 812 5702; E-mail:
[email protected] Seung Jin Kim, Textile Processing Lab. Research staff: J.W. Kim, K.S. Park, J.S. Yu, S.D. Hong, Y.S. Kim, B.K. Seo
A counterplan of textile process and cause analysis of fabric streaky phenomena in synthetic fabrics Other partners: Academic Industrial None S.I. Shin Project started: 1 April 2000 Project ends: 31 December 2000 Finance/support: US$86,000 Source of support: Korea Textile Development Institute (KTDI) Keywords: Streaky phenomena, Yarn texturing, Pirn winder, Jumb winder, Heating temperature, Yarn tension, Thermal stress, Thermal shrinkage This project surveys a counterplan of each process and cause analysis of fabric streaky phenomena in synthetic fabric manufacturing processes such as yarn texturing, weaving preparatory and dyeing and finishing processes. For this purpose, first, the cause for the fabric streaky development are surveyed, and experimental designs in each of the processes such as yarn texturing, pirn winder, 2-for-1 twister, steam setting m/c and jumbo winder are made and analysed. The tensions on the pirn winder are selected at three levels, 15gr., 20gr. and 25 gr., the variable factors on the 2-for-1 twister are r.p.m., ball weight and winding hardness, the r.p.m. is chosen at two levels, i.e. 10,000 and 11,000 and the ball weight on the 2-for-1 twister is chosen at three levels, 3T, 5T
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and 6T, and cheese hardness is chosen at two levels i.e. 55°C and 75°C. The setting conditions in the steamer after 2-for-1 twister are chosen at three levels respectively; one is heating temperature (60°C, 70°C and 80°C) and the other is heating time (30 min., 50 min., and 60 min.). The processing condition on the jumbo winder was selected as yarn feed speed (400m/min., 500m/min., and 600m/min.). and yarn tension (12gr., 15gr. and 18gr.). All specimens prepared by the experimental design are analyzed and discussed with various processing conditions through the analysis of physical properties of yarns and fabrics. The experimental items for yarn physical properties are yarn count, yarn tenacity and strain, thermal stress, thermal shrinkage; these physical properties are also analyzed according to the cheese layers and yarn tension at each processing condition is measured and will be discussed with each processing condition. Project aims and objectives •
Measurement of yarn physical properties according to the weaving preparatory conditions.
•
Determination of the optimum conditions related to the tension in the textile processing.
•
Prevention of fabric streaky phenomena.
Academic deliverables •
One or more graduate theses.
Industrial deliverables •
Co-working with industry and presenting the results to small and medium industries.
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: (053) 810 2536; Fax: (053) 812 5702; E-mail:
[email protected] Seung Jin Kim, Textile Processing Lab. Research staff: J.W. Kim, K.S. Park, J.S. Yu, S.D. Hong, Y.S. Kim, B.K. Seo
The development of the drawing system and physical properties of drawn acryl staple yarns
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Other partners: Academic Industrial None Ok Kyo Seo Project started: 1 July 1999 Project ended: 30 June 2000 Finance/support: US$17,000 Source of support: Ministry of Commerce, Industry and Energy Keywords: Drawing, Acryl staple yarn, Heat treatment, Silk-like yarn, Wet heat shrinkage, Dry heat shrinkage, Setting temperature This project surveys the development of drawing system of acryl staple yarns and the determination of the optimum drawing and heat treatment conditions on this drawing system for making the silk-like yarns from acryl staple yarns. Using these yarns, silk-like knitted and woven fabrics were made. Acryl staple single yarns such as 1/36, 1/52 and 1/66 Ne count were doubled and setted using 2-for-1 twister and drawn under hank state by a drawing system which was made by our project team. Setting temperature and time are changed in the steamer as yarns are drawn, and the drawn yarn physical properties such as tensile property, wet and dry heat shrinkages and snarl index were measured and discussed with various heat setting temperatures. Finally, woven and knitted fabrics made by these silk-like acryl yarns are presented as a sample of this research. Project aims and objectives •
Development of new silky acryl knitted fabric using the drawing system of staple yarn.
•
Establishment of production technology of fine count staple yarn using the drawing system made by this project team.
Academic deliverables •
One or more graduate theses.
•
Presentation to a seminar as a paper.
Industrial deliverables •
Manufacturing procedures for implant for making textile goods.
Publications Kim, S.J. (1999), “The development on their drawing system and physical properties of drawn acryl fibers”, International Symposium on New Frontiers, KIT, Kyoto, Japan, p. 1. Kim, S.J. (2000), “The physical properties of drawn acryl staple yarns and development of their fabrics”, The 80th World Conference of the Textile Institute, No. 45, Manchester, UK. Kim, S.J., Seo, O.K., Jin, Y.D., Son, J.H., Lee, J.G. and Han, W.S. (1999), “The heat treatment conditions and physical properties of drawn acryl staple yarns”, Proceedings of the Korean Textile Conference, Vol. 33 No. 1, pp. 451-4.
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Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: (053) 810 2536; Fax: (053) 812 5702; E-mail:
[email protected] Seung Jin Kim, Textile Processing Lab. Research staff: J.W. Kim, K.S. Park, J.S. Yu, S.D. Hong, Y.S. Kim, B.K. Seo
Analysis of actual condition on the operation of research centers related to the textile and information all over the world Other partners: Academic Industrial None None Project started: 1 June 2000 Project ends: 30 December 2000 Finance/support: US$17,000 Source of support: Korea Textile Development Institute (KTDI) Keywords: Infrastructure, Textile research centre This project critically analyses the infrastructure of textile research centers all over the world with the present situation of the fibre and textile industries in the world. The second part of the study surveys the current trends of research centers in Asia and Europe, with the emphasis on the prospects and roles of research-infrastructure in relation to the developments of fibre and textile industries. Finally, recent research infrastructure establishment in Korea is introduced, and the possibility of efficient operation of this research infra system is shortly predicted. Project aims and objectives • Survey of the textile research infra system in Korea through analysis of textile research centers in Asia and Europe. Academic deliverables • Presentation to seminar as a paper. Industrial deliverables • Presentation to forum of SMEs. Publications Kim, S.J. (2000), “The prospect and roles of research infra system on the fibre and textiles in the Asian comparing to the European countries”, Asian International Symposium on Fibres and Textiles, Kumma, Japan, 5 October. Kim, S.J. (2001), “Milano project/structure of Korea textile”, The 81st Textile Institute World Conference, Melbourne, Australia, 1-4 April.
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Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: (053) 810 2536; Fax: (053) 812 5702; E-mail:
[email protected] Seung Jin Kim, Textile Processing Lab. Research staff: W.S. Han, T.C. No, Y.D. Jin, W.H. Han
A study of optimum production condition for the development of the PET composite yarns for knitted fabrics Other partners: Academic Industrial Tae Hoon Kim M.S. Lee Yeungnam University B.H. An Project started: 1 March 2000 Project ended: 28 February 2001 Finance/support: US$20,000 Source of support: Ministry of Science & Technology Keywords: Knitted yarns and fabrics, PET composite yarns, Pre-twist texturing M/C, Bulkiness of knitted fabrics This project is aiming to develop knitted yarns and fabrics using PET composites yarns such as PET/Acryl, PET/Acetate, PET/Rayon and PET/Natural yarns. This project includes the development of optimum production condition on the composite yarn manufacturing machineries such as pre-twist texturing machine and blend twisting machine of two- or threefold yarn. Using these yarns, knitted fabrics are made and the bulkiness of knitted fabrics are measured and discussed, with various knitted yarns, optimum knitted yarn manufacturing conditions being decided. Project aims and objectives Objective of this project is to develop knitted yarns and fabrics of PET/PET, PET/Acryl, PET/Acetate, PET/Rayon and PET/Natural yarns using pre-twist texturing machinery. The optimum production conditions for the best knitted fabrics are decided and discussed in relation to various knitted yarns. Academic deliverables • One or more graduate theses. • Presentation to seminar as a paper. Industrial deliverables • Manufacturing procedures for implant for making textile goods.
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Publications Hong, S.C., Lee, H.J., Cho, D.H. and Kim, S.J. (1999), “A study of the mechanical properties to the weight reduction rate of PET fabric (III)”, Journal of the Korean Society of Dyers and Finishers, Vol. 11 No. 1, p. 1. Jeong, K.S., Lee, J.S. and Kim, S.J. (1999), “Development of PET/staple composite knitted yarns and fabrics using disk twist device”, The 5th Asian Textile Conference, Kyoto, Japan, p. 1032. Lee, J.G., Jeon, G.H. and Kim, S.J. (1999), “The study on the physical properties of DTY produced by pin and belt, disk false twist texturing systems”, Proceedings of the Korean Society of Dyers and Finishers, p. 155. Lee, J.G., Kim, S.J., Kim, T.H., Son, J.H. and Jin, Y.D., “Effect of processing conditions on the physical properties of DTY composite yarn”, Proceedings of the Korean Textile Conference, p. 455. Lee, M.S., Kim, S.J. and Park, K.S. (2000), “Effect of processing condition on the belt-type texturing M/C to the yarn tension”, Proceedings of the Korean Textile Conference, Vol. 33 No. 2. Kim, J.W., Kim, S.J. and Kim, T.H. (2000), “A study on the properties of ATY produced with nylon FDY and POY”, Proceedings of the Korean Textile Conference, Vol. 33 No. 2. Kim, Y.H., Kim, S.J. and Hong, S.C. (1999), “The study on the physical property between MTS and ring spun yarn”, Proceedings of the Korean Textile Conference, p. 314. Ryu, D.H., Lee, U.J., Kim, S.J., Song, M.K., Cho, J.H. and Jung, M.S. (1999), “A study on the comfort and skin temperature on the clothing environment in the Taegu City during years – concentrated on indoor uniforms”, J. Kor. Soc. Cloth. Ind., Vol. 1 No. 4, p. 376. Son, J.H., Kim, S.J., Jin, Y.D., Lee, J.G. and Kim, T.H. (1999), “The study on effect of dry heat treatment on shrinkage of PET filament”, Proceedings of the Korean Society of Dyers and Finishers, p. 148.
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: (053) 810 2536; Fax: (053) 812 5702; E-mail:
[email protected] Seung Jin Kim, Textile Processing Lab. Research staff: J.W. Kim, K.S. Park, J.S. Yu, S.D. Hong, Y.S. Kim, B.K. Seo
A study on the weavability and mechanical properties of polyester fabric by the various rapier weaving machines Other partners: Academic
Industrial M.H. Park Project ended: 30 June 2000
Project started: 1 July 1999 Finance/support: US$17,000 Source of support: Ministry of Science & Technology
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Keywords: Weavability, Polyester fabric, Shrinkage, Fabric mechanical properties This project surveys the fabric weavability and mechanical properties of polyester fabrics by the various rapier weaving machines such as Omega-E4X, Picanol-GTX, Omega-panter and Vamatex P1001. Using these looms, five harness polyester satin fabrics were woven, used warp yarn count was 150d/48f, and filling was 200d/384f/40d composed of polyester filaments and polyurethane spandex. The same processes of dyeing and finishing processes were applied. Various weavability parameters were measured and discussed with various looms characteristics. The variations of shrinkage of the fabrics according to the kinds of rapier looms on the dyeing and finishing processes were analysed and discussed. In addition, the fabric mechanical properties were analysed and discussed in connection with the various rapier looms, according to the dyeing and finishing processes. Project aims and objectives •
Comparison of physical properties of polyester fabrics woven by domestic looms (Omega, Korea) and foreign looms (Picanol and Vamatex).
•
Comparison of warp and weft tensions during weaving between domestic looms (Omega, Korea) and foreign looms (Picanol and Vamatex).
Academic deliverables •
One or more graduate theses.
•
Presentation to seminar as a paper.
Industrial deliverables •
Manufacturing procedures for implant for making textile goods.
Publications Jin, Y.D. and Kim, S.J. (2000), “The loom characteristic effects on mechanical properties of PET fabrics”, Proceedings of the Korean Society of Dyers and Finishers, Vol. 12 No. 1, pp. 173-7. Jin, Y.D., Jeon, K.H., Kim, S.J., Park, M.H. and Han, W.S. (1999), “The physical properties and shrinkage in the dyeing and finishing processes of PET fabrics produced by rapier loom (II)”, Proceedings of the Korean Society of Dyers and Finishers, pp. 135-9. Kim, S.J. and Yeo, G.D. (1999), “Fabric weavibility and machine efficiency in the various weaving machines such as projectile, rapier and air-jet”, 2nd International Textile and Apparel Conference, Rio de Janeiro, Brazil. Kim, S.J., Yeo, G.D., Park, M.H. and Kim, T.H. (1999), “A study on the weavability and mechanical properties of polyester fabric by the various rapier weaving machines”, Proceedings of the 5th Asian Textile Conference, Kyoto, Japan, 1999, pp. 1032-5.
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Kim, S.J., Yeo, G.D., Cho, J.Y., Son, J.H. and Jeon, K.H. (1999), “The comparison of weavability between Omega loom and Picanol-GTX loom”, Proceedings of the Korean Textile Conference, pp. 152-6. Son, J.H. and Kim, S.J. (2000), “The effect of weaving machine characteristics on the mechanical properties of PET fabrics”, Proceedings of the Korean Society of Dyers and Finishers, Vol. 12 No. 1, pp. 166-72. Son, J.H., Kim, S.J., Jin, Y.D. and Kim, J.W. (2000a), “The effect of weaving machine characteristics on the physical properties of PET fabrics (III)”, Proceedings of the Korean Textile Conference, Vol. 33 No. 1, pp. 153-6. Son, J.H., Kim, S.J., Jin, Y.D. and Kim, J.W. (2000b), “The effect of weaving machine characteristics on the physical properties of PET fabrics (IV)”, Proceedings of the Korean Textile Conference, Vol. 33 No. 1, pp. 157-60. Son, J.H., Jeon, K.H., Kim, S.J., Cho, J.Y. and Lee, J.K. (1999), “The physical properties and shrinkage in the dyeing and finishing processes of PET fabrics produced by rapier loom (I)”, Proceedings of the Korean Society of Dyers and Finishers, pp. 129-34. Yeo, G.D., Kim, S.J., Park, M.H., Lee, J.K., Jin, Y.D. and Han, W.S. (1999), “The comparison of weavability between Omega loom and Vamatex loom”, Proceedings of the Korean Textile Conference, pp. 157-60.
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: (053) 810 2536; Fax: (053) 812 5702; E-mail:
[email protected] Seung Jin Kim, Textile Processing Lab. Research staff: J.W. Kim, K.S. Park, J.S. Yu, S.D. Hong, Y.S. Kim, B.K. Seo
Development of PET/staple composite knitted yarns and fabrics using disk twist device Other partners: Academic
Industrial S.I. Shin Project ended: 30 June 2001
Project started: 1 July 2000 Finance/support: US$17,000 Source of support: Ministry of Commerce, Industry and Energy Keywords: Disk twist devices, Viscose rayon, Pre-twist, Post-twist, Composite yarns, Circular knitting, Weft knitting
The objective of this project is to develop the disk-twist device and the PET/staple composite yarns using this disk-twist device. First, the various disk-twist devices such as various engraved shapes on the navel in the open-end rotor spinner are made and attached on the winder. Filaments used were viscose rayon 150d and polyester 70d/24f; 40 specimens are prepared using various
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disk-twist devices and disk vibrating conditions. These specimens are processed on the pre-twist and post-false twist machines with processing conditions of S618/Z2200 and heat temperature 200°C. The physical properties of these specimens are measured and discussed with various disk-twist devices and processing conditions. The optimum conditions for good yarn physical properties are decided and the knitted fabrics with composite yarns produced under the optimum conditions are made using circular and weft knitted machinery. Project aims and objectives • Development of disk-twist device and application to filament twisting on winder. • Development of knitted yarns and fabrics using this disk-twist device Academic deliverables • One or more graduate theses. • Presentation to seminar as a paper. Industrial deliverables • Manufacturing procedures for implant for making textile goods. Publication Kim, S.J., Shin, S.I., Kim, T.H., Son, J.H., Kim, J.W. and Park, K.S. (2000), “Development of PET/staple composite knitted yarns and fabrics using disk-twist device”, Proceedings of the Korean Textile Conference, Vol. 33 No. 1, pp. 145-8.
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: (053) 810 2536; Fax: (053) 812 5702; E-mail:
[email protected] Seung Jin Kim, Textile Processing Lab. Research staff: J.W. Kim, K.S. Park, J.H. Son, K.L. Kim
A study of optimum production condition for the development of the composite yarns and fabrics for the natural/PET garment Other partners: Academic Project started: 1 March 2000
Industrial S.H. Park, W.H. Han, T.C. No, S.H. Lee Project ended: 28 February 2001
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Finance/support: US$50,000 Source of support: Ministry of Science & Technology Keywords: Weaving preparatory m/c, 2-for-1 twister, Winder, Yarn texturing, Composite twister, Thermal shrinkage, Thermal stress, Yarn bulkiness The objective of this project is to develop attachment of weaving preparatory machinery such as 2-for-1 twister, winder, yarn texturing machinery, twister and composite twister for developing the composite yarns and fabrics for natural/PET garment. In addition, the optimum processing conditions such as yarn tension, guide position, over feed and yarn feed speed are surveyed with various natural/PET composites yarns such as viscose/PET, cotton/PET, rayon/PET, wool/PET and acryl/PET. And the various physical properties of the composite yarns such as thermal shrinkage, thermal stress, tensile modulus, yarn bulkiness and elastic recovery are measured and discussed with various processing conditions. Using these yarns, fabrics are made and their physical properties are measured and discussed with various yarn properties. Project aims and objectives This project aims to develop attachment of 2-for-1 twister, winder, yarn texturing machine, ordinary twister and composite twister for composite yarns. And optimum processing conditions are decided for these weaving preparatory machines. Academic deliverables • One or more graduate theses. • Presentation to seminar as a paper. Industrial deliverables • Manufacturing procedures for implant for making textile goods. Publications Cho, D.H., Kim, S.J. and Chang, D.H. (1999), “Effects of heat temperature in sizing and pre-treatment processes on the appearance colour of the polyester fabrics”, Journal of the Korean Society of Dyers and Finishers, Vol. 11 No. 2, p. 65. Cho, D.H., Kim, S.J., Park, K.S., Kim, Y.S. and Hong, S.D. (2000), “The effect of heat temperature in dyeing and finishing processes on the shear properties of polyester fabrics”, Proceedings of the Korean Society of Dyers and Finishers. Cho, D.H., Kim, S.J., Seo, B.K., Kim, J.W. and Yu, J.S. (2000), “The effect of heat temperature in dyeing and finishing processes on the surface properties of polyester fabrics”, Proceedings of the Korean Society of Dyers and Finishers. Han, W.S., Kim, S.J., Son, J.H. and Nam, K.K. (2000), “The development of tension control devices attached on the winders”, Proceedings of the Korean Society of Dyers and Finishers. Jeoung, K.S., Lee, J.S. and Kim, S.J. (1999), “Development of a twisted compound yarn manufacturing method using a two-for-one twister”, Proceedings of the 5th Asian Textile Conference, Kyoto, Japan, p. 490. Jin, Y.D., Kim, S.J., Son, J.H. and Lee, J.G. (1999a), “A study on cause analysis of streaky phenomena in the PET fabrics”, Proceedings of the Korean Society of Dyers and Finishers, p. 153.
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Jin, Y.D., Kim, S.J., Son, J.H. and Lee, J.G. (1999b), “The effect of wet heat treatment on shrinkage of PET filament”, Proceedings of the Korean Society of Dyers and Finishers, p. 163. Kim, S.J., An, B.H. and Lee, M.S. (1999), “Effect of processing condition of texturing M/C on the physical properties of textured polyester filament”, Journal of the Korean Society of Dyers and Finishers, Vol. 11 No. 6, p. 356. Kim, S.J., Lee, J.G., Yoon, S.K. and Kim, T.H. (2000), “The physical properties and processing conditions of PET composites filament yarns”, The Fiber Society, Guimaraes, Portugal, p. 141. Lee, S.J., Kim, S.J., Han, W.H., No, T.C., Jin, Y.D. and Son, J.S. (1999), “The effect of processing conditions of interlace textured yarn on the physical property of new fibre (I)”, Proceedings of the Korean Textile Conference, p. 86. No, T.C., Lee, S.H., Kim, S.J., Han, W.H. and Lee, S.J. (1999), “Effect of processing conditions of interlace textured yarn on the physical property of new fibre (II)”, Proceedings of the Korean Society of Dyers and Finishers, p. 158. Park, S.H., Kim, S.J. and Kim, J.W. (2000a), “A study on the physical properties of solo spun and ring spun fabrics (I)”, Proceedings of the Korean Textile Conference. Park, S.H., Kim, S.J. and Kim, J.W. (2000b), “A study on the physical properties of solo spun and ring spun fabrics (II)”, Proceedings of the Korean Society of Dyers and Finishers.
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: (053) 810 2536; Fax: (053) 812 5702; E-mail:
[email protected] Seung Jin Kim, Textile Processing Lab. Research staff: J.W. Kim, K.S. Park, J.S. Yu, S.D. Hong, Y.S. Kim, B.K. Seo
Silk-like technology of nylon filament using the texturizing system Other partners: Academic
Industrial Suk Min Hong Project ended: 30 June 2000
Project started: 1 July 1999 Finance/support: US$17,000 Source of support: Ministry of Commerce, Industry and Energy Keywords: Nylon, Dye affinity, Sewability, Sewing, Silk fabric, Solvent modification, Texturizing system
This project surveys development of silk fabric with scrooping hand and luster by solvent modification of nylon filament using fluid yarn texturizing system. Also, possibility of capsulation of the functional agent in the filament is proposed. Nylon has good moisture absorption and dye affinity compared to polyester. Besides, garment sewability is better than that of polyester, and dyeing temperature of nylon is lower than that of polyester. But, despite these
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merits of nylon filament, the weak point of nylon is hand, i.e. natural silk-like hand does not come out. Acryl filament was being used as the fibre material for Korean women’s dress. Many problems for acryl material in sewing, cutting and pressing in garment manufacturing process are occurring, then the limitation of material development for acryl filament makes nylon filament applying to the development of garment materials. This project surveys development of silk fabric with scrooping hand and lustre by solvent modification of nylon filament using fluid yarn texturizing system; the possibility of capsulation of the functional agent in the filament is proposed. Project aims and objectives • Application of texturing system to develop silk-like yarns and fabrics using nylon filament. • Confirm the possibility of solvent modification to nylon filament. Academic deliverables • One or more graduate theses. • Presentation to seminar as a paper. Industrial deliverables • Manufacturing procedures for implant for making textile goods. Publications Kim, S.J. (1999), “Silk-like technology of nylon filament using texturizing system”, Proceedings of the International Conference on Advanced Fiber Material, KIT, Kyoto, Japan, pp. 215-16. Kim, S.J. (2000), “Silk-like technology of nylon filament using texturizing system”, Chemical Fiber International, Vol. 60 No. 81.
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: 82-53-8102536; Fax: 82-53-8125702; E-mail:
[email protected] Seung-Jin Kim, Textile Processing Lab. Research staff: S.B. Shin, S.Y. Kim, M.Y. Park
A study of optimum production condition for the development of the PET composite yarns for knitted fabrics Other partners: Academic Tae Hoon Kim
Industrial B.H. Ahn, K.Y. Kim
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Project started: 1 March 1999 Project ends: 28 February 2002 Finance/support: US$35,000 Source of support: Ministry of Science & Technology; Nine small and medium textile companies Keywords: Knitted yarns and fabrics, PET composites yarns, Pre-twist texturing M/C, Bulkiness of knitted fabrics This project is aiming to develop knitted yarns and fabrics using PET composites yarns such as PET/Acryl, PET/Acetate, PET/Rayon and PET/natural yarns. This project includes the development of optimum production condition on the composite yarn manufacturing machineries such as pre-twist texturing machine and blend twisting machine of two or threefold yarns. Using these yarns, knitted fabrics are made and the bulkiness of knitted fabrics are measured and discussed with various knitted yarns, and optimum knitted yarn manufacturing conditions are decided. Project aims and objectives Objective of this project is to develop knitted yarns and fabrics of PET/PET, PET/Acryl, PET/Acetate, PET/Rayon and PET/natural yarns using pre-twist texturing machinery. The optimum production conditions for the best knitted fabrics are decided and discussed with relation to various knitted yarns. Academic deliverables •
one or more graduate theses;
•
presentation to seminar as a paper.
Industrial deliverables •
manufacturing procedures for implant for making textile goods.
Publications Han, W.H., Lee, S.H., Lee, S.J., Noh, T.C. and Kim, S.J. (2001), “Effect of processing conditions of ITY on the physical properties of compound yarn for new synthetic fabrics(II)”, Journal of the Korean Society of Dyers and Finishers, Vol. 13 No. 2, pp. 49-54. Hong, S.D., Kim, S.J., Seo, B.K., Sim, S.B. and Kim, J.W. (2001), “Effect of fabric manufacturing process characteristics on the PET handle for clothing”, Proceedings of the Korean Society for Clothing Industry, pp. 130-4.
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: 82-53-8102536; Fax: 82-53-8125702; E-mail:
[email protected]
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A study of optimum production condition for the development of the composite yarns and fabrics for the natural/PET garment Other partners: Academic Industrial None W.H. Han, T.C. No, M.S. Lee Project started: 1 March 1999 Project ends: 28 February 2002 Finance/support: US$58,000 Source of support: Ministry of Science & Technology; 15 small and medium textile companies Keywords: Weaving preparatory m/c, 2-for-1 twister, Winder, Yarn texturing, Composite twister, Thermal shrinkage, Thermal stress, Yarn bulkiness The objective of this project is to develop attachment of weaving preparatory machinery such as 2-for-1 twister, winder, yarn texturing machinery, twister and composite twister for developing the composite yarns and fabrics for natural/PET garment. In addition, the optimum processing conditions such as yarn tension, guide position, over feed and yarn feed speed are surveyed with various natural/PET composites yarns such as Viscose/PET, Cotton/PET, Rayon/PET, Wool/PET and Acryl/PET. And the various physical properties of the composite yarns such as thermal shrinkage, thermal stress, tensile modulus, yarn bulkiness and elastic recovery are measured and discussed with various processing conditions. Using these yarns, fabrics are made and their physical properties are measured and discussed with various yarn properties. Project aims and objectives This project aims to develop attachment of 2-for-1 twister, winder, yarn texturing machine, ordinary twister and composite twister for composite yarns. And optimum processing conditions are decided for these weaving preparatory machines. Academic deliverables •
one or more graduate theses;
•
presentation to seminar as a paper.
Industrial deliverables •
manufacturing procedures for implant for making textile goods.
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Publications Hong, S.D., Kim, S.J. and Park, K.S. (2001), “Effect of the manufacturing process characteristics of PET fabrics on the clothing sensibility”, Proceeding of the 2001 Spring Conference of Korean Society for Emotion & Sensibility, p. 23. Park, K.S., Kim, S.J., Yu, Z.S., Kim, Y.S, Kim, S.Y. and Park, M.Y. (2001), “Effect of fabric manufacturing process characteristics on the sewability of PET garment”, Proceedings of the Korean Society for Clothing Industry, pp. 125-9.
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: 82-53-8102536; Fax: 82-53-8125702; E-mail:
[email protected] Seung-Jin Kim, Textile Processing Lab. Research staff: B.K. Seo, S.D. Hong, S.B. Sim
Development of knit and woven fabrics using drawn worsted yarns and their drawing system Other partners: Academic Industrial None O.K. Seo Project started: 1 July 2001 Project ends: 30 June 2003 Finance/support: US$24,600 Source of support: Ministry of Commerce, Industry & Energy Keywords: Worsted drawing yarns, Silk-like worsted yarn, Drawing ratio, Heating temperature This project surveys manufacturing technology of the silk-like worsted yarns and fabrics, and includes development of the drawing system of worsted staple yarn. Using this drawing system, optimum drawing ratio and temperature are decided. Fine staple worsted yarns (100 Nm) are made from 66 Nm and 52 Nm staple worsted yarns using the drawing system. The optimum conditions in the drawing process such as drawing ratio and temperature for linen-like and silk-like knitted fabrics are decided through various experiments. The physical and mechanical properties of the specimens of the yarns and knitted fabrics are measured and discussed with various processing conditions in the drawing system. The yarn physical properties measured are thermal shrinkage, snarl index, bending rigidity, torsional rigidity, and fabric mechanical properties are tensile, bending, shear, compression and surface.
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Project aims and objectives Objectives of this research are to develop the linen-like and/or silk-like worsted yarn for knitted fabric. Also this project aims at the development of drawing machinery for worsted yarns, which is available to control draw ratio and drawing temperature, and includes the determination of the optimum twist condition. Academic deliverables • one or more graduate theses; • presentation to seminar as a paper. Industrial deliverables • manufacturing procedures for implant for making textile goods. Publication None
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: 82-53-8102536; Fax: 82-53-8125702; E-mail:
[email protected] Seung-Jin Kim, Textile Processing Lab. Research staff: K.S. Park, J.S. Yu, B.K. Seo, S.D. Hong, Y.S. Kim, S.B. Sim, S.Y. Kim, M.Y. Park
Comparison of physical properties of PET produced in domestic and foreign industries for enhancing fabric quality Other partners: Academic None
Industrial Korea Textile Development Institute, Taegu-Kyeongbuk Silk & Synthetic Weaving Industrial Cooperation Project ends: 31 December 2001
Project started: 1 June 2001 Finance/support: US$15,300 Source of support: Korea Textile Development Institute Industrial, TaeguKyeongbuk Silk & Synthetic Weaving Industrial Cooperation Keywords: POY, FDY, Layer, Fineness, Thermal shrinkage, Thermal stress, Modulus
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This project surveys present status of quality on the polyester filament yarns (POY and FDY) which are used in Korean weaving industry. For this purpose, two POY (85d/72f and 120d/24f) and two FDY (75d/36f and 50d/24f) are selected. Seven filament manufacturers in domestic and two filament manufacturers in foreign countries are also selected as suppliers of filament specimens. All specimens (cake state) are divided into 20 layers, the physical properties of each layer’s filament are measured and analysed with comparison between layers and manufacturers. The physical properties measured are fineness, thermal shrinkage (wet and dry), modulus, breaking stress and strain, thermal stress. Weaving preparatory and texturizing process conditions are predicted through analysis of these experimental results. Project aims and objectives •
Enhancing fabric quality.
•
Counterplan of fabric streaky phenomena in synthetic fabrics.
•
Inducement of quality assurance in domestic filament manufacturers.
Academic deliverables •
one or more graduate theses;
•
presentation to seminar as a paper.
Industrial deliverables •
research report is delivered to small and medium weaving preparatory companies and seminar is held to them.
Publication None
Kyeongsan, Korea School of Textile & Fashion, Yeungnam University, 214-1 Daedong, Kyeongsan, Korea Tel: 82-53-8102536; Fax: 82-53-8125702; E-mail:
[email protected] Seung-Jin Kim, Textile Processing Lab. Research staff: B.K. Seo, S.D. Hong, S.B. Sim
Strategic direction on the research and development of technical textiles in Korean textile industry
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Other partners: Academic Industrial Tae Hoon Kim H.J. Jang Project started: 1 September 2001 Project ends: 31 December 2001 Finance/support: US$23,000 Source of support: Ministry of Commerce, Industry and Energy; TaeguKyeongbuk Silk & Synthetic Weaving Industrial Cooperation Keywords: Technical textile, Over-production, Garment oriented textile goods This project surveys strategic direction on the research and development of technical textiles in Korean textile industries, especially in Daegu-Kyeongbuk textile region. For this purpose, first, the present industry status on the technical textiles in Taegu-Kyeongbuk region is surveyed including the status of technical textiles in the whole of Korea. The present status of advanced countries in relation to the technical textiles of the USA, European countries and Japan is also examined with technical textile goods of various famous companies. Finally, manufacturing field and goods with their own manufacturing facilities of textile industries in Taegu-Kyeongbuk region are recommended and predicted for distributing their production facilities and refraining from overproduction of garment oriented textile goods. Project aims and objectives •
survey on possibility of production of technical textiles with production facilities for the garment textile goods;
•
distribution of production facilities for the garment oriented textile goods; and
•
refraining from over-production of garment oriented textile goods.
Academic deliverables •
one or more graduate theses;
•
presentation to seminar as a paper.
Industrial deliverables •
research report is delivered to small and medium weaving and yarn preparatory companies and seminar is held to them.
Publication None
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Kyoto, Japan Kyoto Institute of Technology, Faculty of Textile Science, Matsugasaki Sakyo-ku, Kyoto, 606 Japan Tel: (075) 724 7846; Fax: (075) 724 7800 M. Nakamura, T. Matsuo and M. Nakajima, Department of Polymer Science and Engineering
Analyses of tuft forming at bale opener Other partners: Academic None Project started: April 1994 Keywords: Simulation, Tuft, Yarns
Industrial None Project ends: to be continued
The purpose of the bale opener is to open the bale and to produce fine and uniform size tufts for the sequential process of yarn spinning. The opening mechanism at the tuft forming process was investigated, based on theoretical analyses of macroscopic mass balance and of tooth edge locus, and two experimental model tests. A theoretical model of microscopic mass balance was presented to simulate the opening process. Numerical calculations for several process conditions were carried out using the experimental results of model tufting studies. These simulation results have proved to be a good tool for better understanding of the process. The effect of good tuft forming by bale openers on the processibility of the sequential process of yarn spinning and the quality of yarn thus produced was also investigated through production tests of real mills. Project aims and objectives (1) To clarify the opening mechanism at the tuft forming process of the bale opener. (2) To establish simulation technology for the processing. (3) To investigate the effect of good tuft formings by bale openers on the processibility of the sequential process of yarn spinning, and the quality of yarn thus produced. (4) To pursue means towards the improvement of the bale opener. Industrial deliverables Refer to the publication. Publication Nakamura, M., Matsuo, T. and Nakajima, M. (1997), Journal of Textile Machinery Society.
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Kyoto, Japan Kyoto Institute of Technology, Faculty of Textile Science, Matsugasaki Sakyo-ku, Kyoto, 606 Japan Tel: (075) 724 7846; Fax: (075) 724 7800 M.N. Suresh and T. Matsuo, Department of Polymer Science and Engineering
Development of total material design system of woven fabrics for apparel use Other partners: Academic
Industrial
M. Nakajima
T. Harada M. Inoue
Project started: September 1994
Project ends: to be continued
Keywords: Apparel, CAD, Fabric, Woven fabrics Although much research has been done on colour/pattern designing related to fabric appearance and fashion, material design technology for apparel fabrics is still in the developmental stage. A review shows that the past 20 years have witnessed the efforts towards trial construction of partial design systems and conceptualization of total material design logic. The main aim of this part in the series of our studies is to construct a fundamental logical structure of the computer-assisted total material design system for general apparel woven fabrics. The main components of the structure thus constructed and their functions are defined. The system consists of three sections: a user interface, the five design stages starting from conceptual design up to the detailed manufacturing design, and different types of databases which support the design stage. The format and contests of important system components are explained with examples. The executional logic of the system and its flow is also presented with a methodology to find a suitable design solution. Utilization of a “reference sample” has been introduced to simplify the design procedure. Some detailed case studies to illustrate application of this system have been carried out. The frame of the computer system is also being developed. Project aims and objectives To develop a “computer-assisted total material design system of woven fabrics for apparel use”. Academic deliverables Refer to the publications.
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Publications Matsuo, T. and Suresh, M.N. (1997), Textile Progress. Suresh, M.N., Matsuo, T. and Nakajima, N. (1997a), Proceedings of IV Congress ATC, Taipei. Suresh, M.N., Matsuo, T. and Nakajima, N. (1997b), Journal of Text. Mac. Soc., Vol. 50, T146. Suresh, M.N., Matsuo, T. and Nakajima, N. (1997c), Proceedings of 25th Textile Research Symposium, Mt Fuji, Japan. Suresh, M.N., Matsuo, T. and Nakajima, N. (to be published), Journal of Text. Mac. Soc.
Kyoto, Japan Kyoto Institute of Technology, Faculty of Textile Science, Matsugasaki Sakyo-ku, Kyoto, 606 Japan Tel: (075) 724 7846; Fax: (075) 724 7800 D.A. Alimaq and T. Matsuo, Department of Polymer Science and Engineering
Sensory measurements of fabric hand/mechanical properties: part I – worsted fabrics; part II – knitted fabrics Other partners: Academic Industrial M. Nakajima T. Harada Project started: April 1993 Project ends: to be continued Keywords: Fabric, Knitwear, Sensory measurement, Worsted Systems of instrumental method for measuring fabric hand have been fairly successfully developed like KES and its basic way has been well established. On the contrary, systems of sensory method have remained controversial. In this paper, a practical sensory method is proposed on the basis of analogy to sensory colorimetry. Measurement of two kinds of worsted fabrics was conducted by making use of this sensory method. The effective range and the accuracy of this method are discussed based on the data of the above measurement. It is shown that, if a suitable control (temporary standard) sample is chosen, the instrumental values of bending rigidity, thickness and compressibility of worsted fabrics can be estimated by this sensory method with an error of around 20 per cent. The sensory measurement of main mechanical properties of knitted fabrics is now being conducted. Very good results have been obtained so far on these points.
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Project aims and objectives (1) To develop handometry for fabrics by sensory method. (2) To investigate the effectiveness of sensory measurement of fabric mechanical properties.
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Academic deliverables Refer to the publications. Publications Alimaa, D., Matsuo, T., Nakajima, M. and Takahashi, M. (1997), Proceedings of the 25th Textile Research Symposium, Mt Fuji, Japan. Matsuo, T., Harada, T., Saito, M. and Tsutsumi, A. (1995), Journal of Textile Machinery Society, Vol. 48, T244.
Kyoto, Japan Kyoto Institute of Technology, Faculty of Textile Science, Matsugasaki Sakyo-ku, Kyoto, 606 Japan Tel: (075) 724 7846; Fax: (075) 724 7800 T. Matsuo and Ryuichi Akiyama, Department of Polymer Science and Engineering Research staff: Fumitaka Okamoto
Surface mechanical properties of fabrics in terms of hand: part I – Shingosen fabrics Other partners: Academic M. Kinoshita S. Mukhopadhyay K. Izumi Project started: April 1993 Keywords: Fabric, Woven fabrics •
•
•
Industrial None
Project ends: to be continued
A measurement method for surface mechanical properties (especially frictional properties) of fabrics in the relation with their surface hands has been developed. The effects of the friction probe form, probe velocity, probe weight and the selection of suitable parameters representative of frictional properties are investigated. The relationships between surface hand and surface mechanical properties for Shingosen fabrics have been clarified, in comparison with silk-like fabrics and silk fabrics.
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An attempt is also made to simulate frictional properties by certain theoretical structure models of woven fabrics.
Project aims and objectives (1) To develop a measuring method for surface mechanical properties (especially frictional properties) of fabrics. (2) To find the features of these properties and the relationships between hand and these properties. (3) To simulate frictional properties theoretically on the basis of fabric structure. (4) To analyze Shingosen fabrics from the viewpoint of (2). Academic deliverables Refer to the publications. Publications Akiyama, R. et al. (1995), Journal of Textile Machinery Society, Vol. 48, T153. Kinoshita, M. et al. (1997), Journal of Textile Machinery Society, Vol. 50, T187.
Kyoto, Japan Kyoto Institute of Technology, Faculty of Textile Science, Matsugasaki Sakyo-ku, Kyoto, 606 Japan Tel: (075) 724 7846; Fax: (075) 724 7800 K. Kawabe and T. Matsuo, Department of Polymer Science and Engineering
Tow opening of reinforcing fibre and its application for thermoplastic composites Other partners: Academic Industrial None S. Tomoda Project started: June 1994 Project ends: to be continued Keywords: Fibre, Pneumatics, Thermoplastics Impregnation of matrix resin into fibre is further facilitated by using opened tow rather than compacted tow. A new processing system for spreading tow which is composed of plural rolls and a pneumatic device was introduced. Preliminary opening is conducted by threading it on plural fixed rolls under a suitable initial tension. Transverse air of suitable flow velocity is then applied to the tow of steadily sagged form. Some experimental results for carbon fibre and glass fibre, and theoretical analysis on these opening mechanisms were presented. The roles of roll part and pneumatic part were also discussed.
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Thus opened tows have been applied to the impregnation of thermoplastic composites. Significant effect of the tow opening on the facilitation of matrix impregnation has been proved.
54
Project aims and objectives (1) To develop tow opening of reinforcing fibre with high efficiency and low cost. (2) To analyze the opening mechanism. (3) To apply the tow opening technology to the production of thermoplastic composite prepreg. Academic deliverables Refer to the publications. Industrial deliverables At present, laboratorial scale. Publications Kawabe, K., Matsuo, T. and Tomoda, S. (1997), Proceedings of 42nd International SAMPE, Vol. 42, p. 65. Kawabe, K., Tomoda, S. and Matsuo, T. (1997), Journal of Textile Mac. Soc., Vol. 50, T68.
Leeds, UK Leeds Metropolitan University, Calverley Street, Leeds LS1 3HE, UK Tel: (0113) 283 2600; Fax: (0113) 283 3109 Dr A.J. Crispin and Professor G. Taylor
A genetic algorithm approach to leather nesting Other partners: Academic
Industrial Satra R&T Mechatronics Project ends: 31 January 2002
Project started: 1 February 2000 Finance/support: £84,311 Source of support: EPSRC Keywords: Genetic algorithms, Lay planning, Pattern nesting
The research proposes to investigate the problem of leather lay-planning or nesting using a genetic algorithm and associated hybrid techniques which combine genetic and rulebased (both linear and fuzzy) approaches to ascertain whether improvements in yield and processing time can be achieved. In a
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nesting problem, the task is to place stencils (geometric shapes representing component pieces) on a surface (e.g animal hide) so as to minimise the amount of wasted material. The resulting placement is called a marker. The research represents new work as genetic algorithms and knowledgedirected genetic algorithms (hybrid methods) have not been previously applied and evaluated in this field. The research will explore the issues relating to the development of efficient and robust algorithms which would be practically applicable in the leather industries. In leather nesting the quality of the hide has to be taken into consideration prior to stencil placement and the requirement is for high yield with rapid process time. Project aims and objectives The main objectives are: • to contribute to the understanding of genetic algorithms and knowledgedirected genetic algorithms (hybrid methods) as applied to nesting problems particularly with respect to quantifying the issues for efficient and robust performance; • to develop genetic algorithm approaches which are practically applicable in the leather industries; • to evaluate yield and process time performance of the researched algorithms and compare their performance with current state-of-the-art. Research deliverables (academic and industrial) (1) Computer aided simulation of stencil placement (month 6). (2) Genetic algorithm nesting simulation (problem 1) (month 9). (3) Genetic algorithm nesting simulation (problem 2) (month 12). (4) Interim report (month 12). (5) Solution methodologies employed for leather nesting (month 18). (6) Journal paper (month 20). (7) Final report (month 24).
Leeds, UK Leeds Metropolitan University, Calverley Street, Leeds LS1 3HE, UK Tel: (0113) 283 2600; Fax: (0113) 283 3110 E-mail:
[email protected] Dr A.J. Crispin and Professor G. Taylor Research staff: P. Clay
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Genetic algorithm approach to leather nesting Other partners: Academic None
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Industrial SATRA (Shoe and Allied Trade Research Association) R&T Mechatronics Project ends: February 2002
Project started: February 2000 Finance/support: £84,500 Source of support: EPSRC Keywords: Leather, Lay-planning, Nesting, Genetic algorithm, Artificial intelligence
The research investigates the problem of leather lay-planning using genetic algorithm and other evolutionary methods. It is developing new encoding strategies for mapping shape position and angles evolved by an evolutionary algorithm to non-overlapping configurations. Project aims and objectives •
to contribute to the understanding of genetic algorithms as applied to nesting problems particularly with respect to quantifying the issues for efficient and robust performance;
•
to develop efficient genetic algorithm encoding methods for leather nesting
•
to evaluate yield and process time performance of the researched algorithms and compare their performance with the current state of the art.
Research deliverables (academic and industrial) The main benefit will be to the research community involved in twodimensional cutting and packing problems in the textile and leather industries. Publications Clay and Crispin (2001) “Automated lay planning in leather manufacturing”, National Conference of Manufacturing Research, Cardiff , Wales. Others in progress
Liberec, Czech Republic Technical University of Liberec, Faculty of Textiles, 461 17 Liberec, Hálkova 6, Czech Republic Tel: 00420 48 25441/25462
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Professor P. Kirkens, Universiteit Gent, Belgium; TU Liberec part: Professor Stanislav Nosek, Department of Weaving Technology (newly renamed as Department of Mechanical Technologies in Textiles) Research staff: Petr Tumajer, Ingolf Brotz, Ale˘s Cvrkal, ˘ B˘retislav Spidlen and Zora Nejezchlebová Other partners: 17 partners in Europe according to the associated contracts with the Universiteit Gent (both academic and industrial)
Copernicus project “network for studying warp related weaving (associated contract), the part of the TU Liberec”: weavability at high rates Other partners: Academic Industrial None None Project started: 15 January 1997 Project ended: 31 December 2000 Finance/support: ECU20,950 Source of support: Commission of the European Communities (CEC)/ Universiteit Gent, Vakgroep Textilkunde, Gent Keywords: Textiles, Weaving The objective of this complex international project is to exchange formations, co-ordinate research efforts, and perform research in the field of warp-related problems. The research work on the TU Liberec solves the questions arising with increasing weaving rates: problem of stability of weaving and the steadiness of the magnitude of beat-up force (of the beat-up impulse); weavability of high fabric densities and transition; and stop/start bars in fabric density and structure after changing the weaving conditions on the loom, etc. An important factor in these effects is the interaction between the machine parts and the warp and fabric on the loom. One problem of these interactions has been solved among others this year: the problem of friction between the warp and back rest roller and the effect of backward rotation of the roller against the warp motion at high weaving frequencies. Another one is the problem of vectorial composing of various motions of loom parts into a resulting motion, which is additional to the beat-up pulse and produces an s.c. secondary positive or “negative” beat-up. The third problem to be solved is the problem of behaviour of own masses and rheologic properties of the warp during the weaving process. The propagation of deformation of the warp along the loom can affect the weaving process at today’s weaving frequencies.
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Project aims and objectives The aim of the project is to study the influence of machine and textile material properties (dispersed masses of warp, rheological resistances) on the weaving regime on the loom. The weaving process is studied theoretically as well as experimentally by using necessary measuring devices, signal analyzers, and a high-speed TV camera for visualizing the processes. Academic deliverables Mathematical formulation and practical knowledge of properties and behaviour of mechanical systems loom parts-warp and of their influence on the weaving process and arising forces and deformation (translation). Problems are included in doctoral works. Industrial deliverables Use of research results in construction of weaving looms and their parts. Publications Chrpová, E. and N˘eme˘cek, P. (1996), “Schall- und schwingungmessungen zur beurteilung des einstichprozesses bei nadelfilzmaschinen”, Melliand Textilber, March, pp. 122-4. Hanzl, J. (1996), “Diagnostics and measurements on textile machines”, paper, University of Minho, Portugal. Nosek, S. (1996a), “Feedback phenomena in textile processes”, poster and Book of Transaction of 30th International Symposium on Novelties in Textiles, Ljubljana. Nosek, S. (1996b), “Podivné chování sv˚urkového vále˘cku na tkacím stroji” (Peculiar behaviour of the back rest roller on a weaving loom), International Conference IFTOM on Theory of Mechanisms and Working Machines, Liberec. Nosek, S. (1996c), “Vliv vibrací textilních stroj˚u nové generace na zdravotní stav a pracovní pohodu pracovník˚u”, (The influence of vibrations of textile machines on health of workers), Introductory Analysis of the Problem, Ergotest, Olomouc.
Liberec, Czech Republic Technical University of Liberec, Faculty of Textiles, 461 17 Liberec, Hálkova 6, Czech Republic Tel: 00420 48 25441/25462 Professor Stanislav Nosek, Department of Weaving Technology (newly renamed Department of Mechanical Technologies in Textiles) Research staff: Ingolf Brotz, Petr Tumajer, Ale˘s Cvrkal and Jaroslava Richterová
Research of shocks (impacts) and vibrations excited by technological processes in weaving and other textile machines
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Other partners: Academic Industrial None None Project start date: 1998 Project ends: – Finance/support: K˘c1,900,000 (estimated) Source of support: Applied with the Grant Agency of the Czech Republic (GACR) (or will be worked out as an internal project of TU Liberec) Keywords: Textiles, Weaving Many textile technological processes, especially the weaving process, produce during each working cycle a row of force impulses which affect the processed textile material as well as the machine. The impact of these impulses causes the propagation of delayed deformation of both media – textile material and machine parts – so that the deformation can return to the source of impulse through several paths. The result is that the next impulse changes with respect to the previous one and the technological process may become unstable or steadied in a different regime to that originally set on the producing system, etc. That can affect the quality of the produced good. At the same time, the excited shocks and vibrations in the system material – working machine – can be emitted in the air or into the floor as noise or vibrations on a wide band of frequencies and can affect the workers as well as the environment and the building. The problems of arising propagation and damping of technologically affected impulses and vibrations will be studied first on the process of fabric forming of the loom as the effect of beat-up, of shedding, back rest motion, functioning of fabric take-up and warp let-off devices. Later, the research should be widened to further textile processes – winding, warping, etc. Project aims and objectives The aim of the research is mainly to explain why and how the produced goods on textile machines often differ from the structure and quality of the goods originally (theoretically) set on the machine. One possible reason may be the deviated motions of textile material and machine parts caused by impulses and vibrations in these compliable and massive media, which impulses result from the technological process itself. The research will start with the weaving machines. Academic deliverables A new theoretical view on the stability of technological processes as processes of propagation and returning (feedback) of impulses and vibrations in compliable textile material and machine parts in textile technologies. The research will also be explored as the source of problems for training of PhD students.
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Industrial deliverables Results will be applied in textile machines design. Results concerning the propagation of vibrations into the air and into the floor will be used to research the protection of persons as well as buildings against damage by noise and vibrations.
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Publications Hanzl, J. (1995), “The behaviour of the back rest on the loom”, poster and Book of Transactions, International Conference of Young Textile Science, TU Liberec. Nosek, S. (1994a), “The dynamics of fabric forming at high weaving rates”, Industrial Journal of Fibre & Textile Research, Vol. 19 No. 3. Nosek, S. (1994b), “The dynamics of fabric forming on the loom and problems of weavability at high weaving rates”, World Textile Conference, Huddersfield. Nosek, S. (1995a), “Dynamics and stability of beat-up”, Fibers & Textiles in Eastern Europe, Vol. 1 No. 1, Lodz. Nosek, S. (1995b), “Feedback phenomena in textile processes”, International Conference of Young Textile Science, TU Liberec. Nosek, S. (1995c), “Mechanics and rise of stop marks and structural bars in fabrics”, poster and Book of Transactions, IMTEX ’95, Lodz, Polsko. Tumajer, P. (1995), “Dynamics of start of a weaving loom and the possible rise of transition marks”, poster and Book of Transactions, International Conference of Young Textile Science, TU Liberec.
Liberec, Czech Republic Technical University of Liberec, Halkova 6, 461 17 Liberec, Czech Republic Tel: +420 48 5353498; E-mail:
[email protected] Zdene˘k K˚us, Head of Department, Department of Clothing Research staff: Jir˘í Militk´y, Otakar Kunz, Antonín Havelka, Dagmar Ruz˘ ic˘ ková, Vladimír Bajzík, Jana Zouharová, Andrea Halasová, Viera Glombíková, Blaz˘ ena Musilová, Petra Komárková, Jaroslav Beran, Josef Olehla, Miroslav Brzezina
Organoleptic properties of three-dimensional textile objects Other partners: Academic Industrial Other departments of the university Project start date: 1 January 1999 Project ends: 31 December 2004 Finance/support: £70,000 Source of support: Ministry of Education, Technical University of Liberec Keywords: Fabric properties, Comfort, Handle, Thermal
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The research will be performed in the following areas: Surface properties of textile formations, non-linear deformations of fabric • Computer simulation of impact surface parameters of the planispheric textile fabric to their chosen macroscopic properties. This is made with the aim of predicting and optimising these properties. Provide evolution for new measurement methods in this area. • Computer simulation of non-linear deformation of the planispheric textile fabric with ballast, for example, by means methods of final elements. Physiological properties of comfort textile formations, fabric handle • Development of new methods for evaluation of physiology comfort and fabric handle. The following application progressive computers method. For example, the neural networks or the artificial intelligence for comparing objective new parameters with empirical find out values. Thermal properties of textiles sandwich materials • Development of new devices for measurements of thermal properties of textile composites and textiles sandwich materials, with special regard to these materials applied in extreme conditions. • Objectification of the property evaluation of textile materials from the point of view of comfort and hygienic properties. Project aims and objectives New methods of measurement, computer simulation of fabric deformation, etc. Publications Halasova, A. and Glombíková, V. (2000), “Problem of simulation working breakdown apparel production in program accessories Witness”, Proceedings of Textile Science 2000, Liberec, Czech Republic, 12-16 June, ISBN 80-7083-409-9, p. 375. Hes, L., Li, Y. and Kus, Z. (1999), Ochranná textilie proti sálavemu teplu a ochrann´y oblek z této textilie, Czech Republic Patent PV1673-99. Kus, Z. (1999), “Investigation of seam pucker with help of image analysis”, Proceedings of the 5th Asian Textile in the 21th Century Conference, Kyoto, Japan, p. 333. Kus, Z. and Komárková, P. (2000), “Computer simulation of apparel production”, Vlákna a Textil, Vol. 7 No. 2, ISSN 1335-0617, pp. 113-16. Kus, Z., Glombíková, V. and Bradácová, H. (2000), “Application of image analysis and neural network for the evaluation of seam pucker”, Proceedings of Textile Science 2000, Liberec, Czech Republic, 12-16 June , ISBN 80-7083-409-9, pp. 391-3. Trung, N.C. and Kus, Z. (1999), “Computer simulation of sewing needle heating”, Progress in Simulation, Modeling, Analysis and Synthesis of Modern Electrical and Electronic Devices and Systems, World Scientific and Engineering Society Press, Athens, Greece, ISBN 960-8052-08-4, pp. 166-70.
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Louisiana, USA Louisiana State University, 341 Human Ecology Bldg, Baton Rouge, Louisiana 70803, USA Tel: +1 (225) 388-2407; Fax: +1 (225) 388-2697 E-mail:
[email protected] Yan Chen and Billie J. Collier, School of Human Ecology
Objective evaluation of fabric softness Other partners: Academic Industrial None Albemarle Corporation Project started: June 1998 Project ended: June 2000 Finance/support: $47,000 Source of support: LA Board of Regents and Albemarle Corporation Keywords: Fabric properties, Fuzzy evaluation, Kawabata evaluation system, Softeners, Softness With consumers’ great demand for softer fabric handle, softener quality becomes the most concerned issue for softener manufacturers, textile manufacturers, and home and industrial launderers. Sponsored by Albemarle Corporation, the School of Human Ecology has undertaken a research project, Fabric Softener Study (LAES 903-25-6156). The Kawabata Evaluation System for fabrics and some empirical equations have been used to numerically evaluate softener quality. This proposed project will extend the present research work with an emphasis on improving accuracy and reliability of the present methods. Experimental work will be carried out in cooperation with Albemarle Corporation Technical Center. Instrumental measurements will be completed in the school’s testing laboratory. Special attention will be drawn to all possible experimental errors that influence the accuracy of predicting fabric softness. Project aims and objectives This proposed research aims at establishing an industrially applicable method to evaluate fabric softness and hand using instrumental data and a suitable mathematical approach. Major objectives are: (1) to continue present research work on investigating applicability of empirical equations using the Kawabata KES-FB data; (2) to locate variance sources that affect measurement reproducibility; (3) to determine the fabric properties that affect fabric softness most significantly so as to eliminate less important parameters in the empirical equations;
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(4) to improve instrumental measuring methods for fabric mechanical properties to increase measurement sensitivity. Academic deliverables The technology developed by this project will be presented to the industrial partner for immediate industrial application. Research credits for development of this technology will belong to the LSU Agricultural Center and Albemarle Corporation. Industrial deliverables Other potential manufacturers may acquire this technology through negotiation with the LSU Agricultural Center and Albemarle Corporation.
Louisiana, USA Louisiana State University, 341 Human Ecology Bldg, Baton Rouge, Louisiana 70803, USA Tel: +1 (225) 578-2407; Fax: +1 (225) 578-2697 E-mail:
[email protected] Yan Chen, Textile and Limp Material Research Laboratory
Tensile machine-based measuring instruments for mechanical properties of fabrics and limp materials Other partners: Academic None
Industrial MTS System Corporation Material Testing Division Project ended: December 2000
Project started: January 1997 Finance/support: $148,645 Source of support: Louisiana Board of Regents and MTS System Corporation Keywords: Testing instrument, Fabric properties, Kawabata parameters This research is to develop a set of instrument attachments for evaluating mechanical properties of fabrics and limp materials. Mechanical properties to be tested are extension, shear, bending, compression, and friction. This measuring system, driven by a currently available tensile tester and controlled by a compatible PC, can be commercially and inexpensively available for all tensile tester users in different industry sections to meet specific testing requirements. It is particularly useful for manufacturers of textiles, fabrics, and garments in evaluating fabric quality and processability in garment making. Development of these instrument attachments will promote engineering applications of fabric mechanics, and development of physical models for computer simulation of fabric drape and apparel appearance.
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This project will contribute to the development of textile and apparel industries in the state and nation. The developed testing instruments will provide a tool of quality identification and quality control in fabric and garment manufacturing. Because this measuring system is cheaper, faster, and easier to use, small textile firms can afford it as a routine laboratory facility. Direct beneficiaries include fabric producers, finishers, and garment manufacturers who need the KES-FB data for quality control and process manipulation, but cannot afford the expensive KES-FB instruments that are no longer marketed in the USA. Project aims and objectives The overall objective of this research is to develop a set of instrumental attachments for evaluating mechanical properties of fabrics and limp materials (non-linear elastic materials). Mechanical properties to be tested are extension, shear, bending, compression, and friction. This measuring system, driven by a QT/5 tensile tester and controlled by a compatible PC, will be easy to use and inexpensive to obtain for textile manufacturers and other related industries. Proposed research includes: (1) design and construction of devices for tensile, shear, bending, compressive, and frictional testing; (2) completion of an electronic interface between the tensile machine and a PC; and (3) development of testing methods using the software Test Works to measure tensile, shearing, bending, compressive, and frictional properties of fabrics. Research deliverables (academic and industrial) A prototype of the instrumental system was established in the fabric and limp material research laboratory. This system consists of five instrumental attachments; a desktop QTest tensile tester (MTS Corporation) and testing methods and testing methods generated using the software TestWorks Version 3.1 (MTS Corporation). These attachments are driven by the QT/5 tensile tester and controlled by a Pentium PC. Fabric mechanical properties of extension, shear, bending, compression, and friction can be measured by running each individual testing method. Stress-strain curves are saved automatically and are able to output in an ASCII-format for other analyses. The Kawabata parameters also can be computed and saved automatically and printed from both a screen and printer. Publications Chen, Y., Zhang, T. and Gider, A. (2001), “New instrumental method for evaluating fabric softness”, Proceedings of Beltwide Cotton Conferences, Vol. 2, pp. 1298-301. Chen, Y. (2001), New Instrument for Measuring Mechanical Properties of Industrial Fabrics, Industrial Fabrics Association International Expo 2001 Textile Technology Forum, October 17, Nashville, TN.
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Manchester, UK Manchester Metropolitan University, Old Hall Lane, Manchester M14 6HR Tel: 0161 247 2632; Fax: 0161 247 6329; E-mail:
[email protected] Dr J.E. Ruckman, Mrs H. Rowe, Department of Clothing Design and Technology Research staff: Dr A. Popp
Quality control in fashion/textiles supply chains Other partners: Academic Industrial None None Project started: May 1998 Project ended: April 2001 Finance/support: £50,000 Source of support: Faculty Research Fund Keywords: Clothing, Quality control, Supply chains, Testing The internationalisation of the fashion/textile supply chain is an ongoing process. This development is often characterised as being primarily cost driven. However, there are many non-cost dimensions of supply chain internationalisation which remain relatively unexplored. This project seeks to explore the impact of international sourcing on the issue of textile and garment quality. The aim of the project is to identify the place and role of quality within the fashion supply chain, to assess whether this role and position is changing as internationalisation takes place and to evaluate intra- and inter-firm handling of testing and quality issues. An initial literature review has been conducted and a theoretical perspective established. First, the internationalisation of the industry is situated within an industry life-cycle and comparative competitive advantage perspective that seeks to illuminate the strategic attributes of internationalisation. Second, intra- and inter-firm relationships will be approached from an institutional perspective. Thus the study poses questions such as: what is the institutional context within which internationalisation is set? How are issues of governance and coordination handled? Who sets the rules and regulations of testing? A pilot survey of UK retailers and manufacturers, conducted via face-to-face interviews, is currently being undertaken in preparation for a larger questionnaire survey. The third stage of the project will involve devising and conducting a performance test targeted at participating firms and utilising prepared fabric samples. The project will yield qualitative and quantitative data, allowing both the characteristics and performance of varied supply chain configurations to be assessed.
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Publications Two papers have been presented at conferences, including the 80th Textile Institute World Conference, and two papers have been published in journals.
Manchester, UK Manchester Metropolitan University, Department of Clothing Design and Technology, Old Hall Lane, Manchester M14 6HR Tel: (0161) 247 2632; Fax: (0161) 247 6329; E-mail:
[email protected] Dr J.E. Ruckman and Professor R. Murray, Department of Clothing Design and Technology Research staff: Mr J. Qu
Predictive model for determining the onset of internal condensation in performance clothing systems Other partners: Academic Industrial None None Project started: October 1999 Project ends: September 2002 Finance/support: £37,500 Source of support: University Research Fund Keywords: Clothing system, Condensation, Predictive model, Testing method, Water vapour transfer Internal condensation in fabrics is a key factor in reducing the effectiveness of water vapour transfer and hence comfort in high performance clothing systems. A working design for a device to accurately measure and vary temperature and relative humidity on either side of a fabric sample and simulate conditions similar to those encountered under extreme environments has been completed and a prototype machine built. The research project will explore the range of the device’s applicability, reliability and validity and refine the prototype machine via a series of experiments with both standard and high performance clothing materials. Confirmation of performance will be followed by the establishment of a methodology to achieve reproducibility of experimental results. Research will then lead to the construction of a predictive model for internal condensation, its effect on water vapour transfer and comfort of the wearer for performance clothing systems. Together with the objective measurement and theoretical consideration of water vapour transfer, a wearer trial utilising the application of sensory assessment techniques on clothing systems will also be performed.
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Manchester, UK Manchester Metropolitan University, All Saints Building, All Saints, Manchester M15 6BH Tel: (0161) 247 2776; Fax: (0161) 247 6329; E-mail:
[email protected] Dr S.G. Hayes, Jackie Jones, Department of Clothing Design and Technology Research staff: Wendy Bailey
The development of an evaluation system for ergonomic clothing comfort Other partners: Academic Industrial None None Project started: 1 October 1999 Project ends: 31 September 2002 Finance/support: £30,000 Source of support: Manchester Metropolitan University Keywords: Ergonomic, Comfort, Clothing, Functional, Evaluation The broad aim of this project is to develop a subjective evaluation system for the ergonomic comfort of functional clothing. Clothing comfort consists of three elements: thermophysiological, ergonomic, and sensorial. This work will complement the existing understanding of thermophysiological comfort and further extend the ability of organisations to develop innovative clothing with high-performance applications. Garments designed at different levels are being compared with respect to pattern engineering, garment engineering, and seam engineering aspects which can help or hinder movement during a specific activity. A subjective assessment system will provide data to relate wearer comfort to design features. It is envisaged that an extension to this work will include the development of an objective evaluation methodology. Project aims and objectives •
To evaluate clothing comfort, mobility and movement using subjective measures.
•
To establish a relationship between a range of garment designs and ergonomic clothing comfort.
•
To develop a subjective evaluation system for ergonomic clothing comfort.
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Research deliverables (academic and industrial) •
A subjective evaluation system to be adopted by industry.
•
Increased understanding of human/garment interaction.
•
A system of communication to best describe garment comfort.
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Manchester, UK Manchester Metropolitan University, Department of Clothing Design and Technology, Old Hall Lane, Manchester M14 6HR Tel: (0161) 247 2632; Fax: (0161) 247 6329; E-mail:
[email protected] Dr J.E. Ruckman, Department of Clothing Design and Technology Research staff: Dr A.G. Oh
Water vapour transfer through layered clothing systems Other partners: Academic
Industrial
None
None
Project started: 1 October 1999
Project ends: 31 September 2002
Keywords: Clothing systems, Microclimate, Water vapour transfer, Testing method The transfer of water from the human body through clothing to the outside atmosphere is an important factor in human comfort. Many researchers emphasised the importance of studying water vapour through textile fabrics, layered fabrics and clothing systems. However, most studies were carried out under steady-state conditions, with the result that many factors that play an important part in the comfort of the wearer in different conditions were largely ignored. There is also the limitation of instrumental measurements of moisture transfer to simulate the actual comfort performance of clothing and actual termperature and humidity changes in the microclimates. In wear, these textiles and fabrics form part of a layered clothing system. The aims of this research are therefore to establish a suitable technique for the measurement of water vapour transfer through layered clothing systems and to investigate the ways in which the mechanism of water vapour transfer affects the layered clothing systems, and consequently the human body.
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Manchester, UK Manchester Metropolitan University, Department of Clothing Design and Technology, Old Hall Lane, Manchester M14 6HR Tel: (0161) 247 2632; Fax: (0161) 247 6329; E-mail:
[email protected] Dr J.E. Ruckman, Dr S.G. Hayes, Department of Clothing Design and Technology Research staff: Dr J.H. Cho
Development of a perfusion suit incorporating auxiliary heating and cooling systems Other partners: Academic Industrial None None Project started: January 2000 Project ended: January 2001 Finance/support: £20,000 Source of support: Korea Research Foundation Keywords: Cooling garment, Pre-shaped, Exercise Examining the specific effects of temperature change on muscle function is important for athletes, as a decrease in muscle temperature by 1-2°C has been shown to result in a 10-20 per cent decrease in power output, and therefore affects the athletes’ performance in cold environment competition. Increasing muscle temperature has been shown to produce the opposite effect. Examining the specific effects of temperature change on muscle function is also important in understanding individuals’ physiological response to thermal stress, particularly for fire-fighters or cold-store workers who are exposed to extreme environmental temperatures. Traditional studies examining the effects of temperature perturbation on muscle function have commonly employed either water immersion or low-intensity exercise as means of changing muscle temperature. The aim of this research project is to study the feasibility of developing a “perfusion suit” which will be applicable to various needs of an individual for auxilary heating or cooling. The feasibility study will concentrate first on identifying the most appropriate textile material and the method by which the auxilary heating and cooling system is incorporated into the identified textile material. The pilot garment will then be constructed, probably based in the “chaps” design with pockets in the areas of major muscle groups. Various sets of experiments will then be conducted to evaluate empirically the effectiveness of this pilot garment by monitoring changes of human muscle temperature when part of the human body is covered with this basic garment incorporating a basic auxiliary heating and cooling system.
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Maribor, Slovenia University of Maribor, Faculty of Mechanical Engineering, Smetanova 17, 2000 Maribor, Slovenia Tel: +386 62 220-7960; Fax: +386 62 220-7990 Associate Prof. Dr Sc. Jelka Ger˘sak, Institute of Textile and Garment Manufacture Processes, Clothing Engineering Laboratory Research staff: Doc. Dr Karl Gotlih, Darja Z˘uni˘c Lojen, MSc, Zoran Stjepanovi˘c, MSc, Marija Karba, BSc
Methods of kinematics and kinetic values modelling in a stitch formation process Other partners: Academic Industrial None None Project started: April 1997 Project ended: March 2000 Finance/support: SIT4,131,365 or ECU22,112 per year Source of support: Ministry of Science and Technology of Republic of Slovenia Keywords: Kinematics, Sewing, Sewing machines, Stitch The research programme comprised three main parts. The first part is involved with the study of kinematics and kinetics of the sewing machine’s working mechanisms in relation to dynamic loading of thread, aiming to prepare the simulation of stitch formation. The second part refers to the study of requirements, needed to set up the model of the thread and fabric. The third part of the research relates to the simulation of sewing machine mechanisms and their interaction with thread and fabric. Taking into account the planned goals, extended research work on the study of kinematics and kinetics of the sewing machine’s working mechanisms and the model of the thread has been carried out. This research will enable the simulation of sewing machine activity, respectively the simulation of interaction between the sewing machine and thread in stitch formation process. For this purpose the kinematics of particular mechanisms and working elements for stitch formation of a basic sewing machine were studied. Further, the simulation of sewing machine activity on the basis of a needle bar mechanism model was carried out. With simulation of sewing machine activity it is possible to analyse the motion of parts and mechanisms and get the information about motion – displacement, velocities and acceleration. The other research task deals with the problem of the sewing thread model. The simple sewing thread model was formed to enable a simulation of the stitch formation process. To simulate the thread it is necessary to choose the appropriate rheological model which needs to be simple yet capable of sufficiently describing the visco-elastic properties of the thread. For this
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purpose the Kevin-Voight rheological model has been chosen. The constraints from this model were used for the spring-damper in the program package ADAMS in the simulation of the take-up lever-sewing thread system.
Research register
Project aims and objectives The main aims of the project are: •
•
definition of a model of stitch, respectively seam design on the basis of a detailed research of kinematics and kinetics of the sewing machine’s working mechanisms and both elements – thread and garment part, which will be carried out using the suitable simulation; and determination of the influence of particular parameters on a model of stitch formation process, i.e. establishment of a stitch design model which will enable the repeatable process of stitch design.
Academic deliverables New scientific cognition, which will serve for design of a simulation of sewing machine activity, respectively interaction of sewing machine, thread, and garment parts in a sewing process, will be achieved in a frame of a project by establishment of a model of stitch design using the analytical methods and experimental research. Achieved cognition will contribute to development of basic knowledge in a field of clothing engineering. Modelling of kinematics and kinetic values of stitch design will be possible. The above mentioned simulation of a stitch design and thus connected forces will be carried out on the basis of kinematics, static, linear and non-linear analyses, visualisation of movements and dynamic analysis of individual elements behaviour. This will be the basis for development of applied research work. Industrial deliverables The contents of a proposed project are designed in such a way that it will enable the development of applied research work in the field of sewing process parameters optimisation, as well as in the field of planning and development of high quality sewing threads. This will be enabled by modelling of kinematics and kinetic values of stitch design, i.e. by establishment and use of designed models. Publications Stjepanovi˘c, Z. and Strah, H. (1997), “Selection of suitable sewing needle using machine learning techniques”, Proceedings of the 2nd International Conference Innovation and Modelling of Clothing Engineering Processes, Faculty of Mechanical Engineering, Maribor, pp. 1847-89. Z˘unic˘ Lojen, D. (1997), “Simulation of sewing machine mechanisms using programme package ADAMS”, Proceedings of the 2nd International Conference Innovation and Modelling of Clothing Engineering Processes, Faculty of Mechanical Engineering, Maribor, pp. 1847-89. Z˘unic˘-Lojen, D. (1999), “The behaviour of a thread in the stitch formation process”, Proceedings of 10th World Congress on the Theory of Machines and Mechanisms, Oulu University Press, Oulu, Finland, Vol. 2, 20-24 June, pp. 741-4.
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Maribor, Slovenia University of Maribor, Faculty of Mechanical Engineering, Smetanova 17, 2000 Maribor, Slovenia Tel: +386 62 220-7960; Fax: +386 62 220-7990; E-mail:
[email protected] Associate Prof. Dr Sc. Jelka Ger˘sak, Institute of Textile and Garment Manufacture Processes, Clothing Engineering Laboratory Research staff: Daniela Zabec, BSc
Study of the influence of interaction of heat, moisture and pressure on textile material-garment Other partners: Academic None
Industrial MURA European Fashion Design, Murska Sobota Project started: June 1998 Project ended: June 2001 Finance/support: SIT4,390,605 or ECU23,230 for 1998 Source of support: Ministry of Science and Technology of Republic of Slovenia: SIT3,073,424 for 1998, Industrial partner: SIT1,317,181 for 1998 Keywords: Clothing, Iron, Transformation
The aim of the project is investigation of the interaction of the heat, moisture and pressure on a textiles material and its behaviour during ironing process. Ironing of textile materials, respectively clothes, represents a very complex area, because the textile material is in defined time being transformed or changed with help of heat, moisture or vapour and pressure and finally chemical or physically fixed, so that initial form is changed to the proper and relatively stable end form of the material or cloth. There are three material dependent physical-chemical processes; polyester is thermo-plastically transformed and fixed, cotton is performed and fixed in absorption process, while the wool is transformed chemical-physically. The ironing parameters have to be in agreement with these three different transforming mechanisms of the material. For the ironing quality not only is the interaction of the influence of the heat, moisture and pressure important, but also their influence on transforming and dimensional changes in the textile material. The material’s behaviour during ironing also depends on its mechanical and physical properties. The behaviour of shell fabric during ironing process is very difficult to predict, although the mechanical, heat and chemical processes are known. Particularly problematical are areas where the fabric is fused with interlining and on the seam area.
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The knowledge of material properties and their behaviour during the ironing is to be regarded as the basis for the planning of ironing parameters. Project aims and objectives are: •
To study and investigate the influence of interaction of heat, moisture and pressure on textile material – garment; study of the behaviour of garment during ironing;
•
To study the resulting interactions on a change of mechanical and physical properties of the textile material, i.e. above all the relaxation shrinkage and wet extension;
•
To study and investigate the behaviour of the base material and interlining as a joint composite in produced garment during the ironing as well as to investigate the influence of heat, moisture and tension on seam as a joint element of a garment, or interaction fabric – seam, respectively; and
•
To define the optimal ironing processing parameters, i.e. the effect of heat, moisture and pressure on the basis of mechanical and physical properties of fabrics and their behaviour during the ironing process.
Academic deliverables The realisation of the project will result in definition of the interaction of the influence of heat, moisture and pressure on textile surface and thus connected change of mechanical and physical properties of a textile material that is built in a garment. Furthermore, new cognitions regarding the behaviour of textile materials during the ironing process will be achieved. An important achievement that will contribute to the application of results of the project will be the knowledge about the ironing mechanism and deformation model of a textile material, fabric’s surface and seam as garment’s joint element and relationship between these elements: fabric – joint composite – seam. Industrial deliverables The project is conceived in such a way that achieved results of the research will enable optimisation of mechanical and physical properties of a fabric from the point of view of their behaviour during the ironing process. The designed deformation model of a fabric will also enable the optimisation of processing parameters for ironing of garments. Publication Vnuk, R. and Ger˘sak, J. (1998), “Influence of the mechanical and physical properties of a fabric on pressing quality” (Vpliv mehanskih in fizikalnih lastnosti tkanine na kakovost likanja), Proceedings of the IV Symposium Clothing Engineering’98, Faculty of Mechanical Engineering, Maribor, pp. 90-6.
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Minho, Portugal The University of Minho, Centre for Textile Science & Technology, Campus de Azurém, 4800 Guimar~ aes, Portugal Tel: +351 53 510280; Fax: +351 53 510293 Maria José Araújo Marques, Department of Textile Engineering Research staff: Maria Elisabete Cabeço Silva, Dominique Adolphe, Laurence Schacher and António Alberto Cabeço Silva
Contribution to the parameter setting study for disposable textiles used in the health-care sector Other partners: Academic ENSITM – Ecole Nationale
Industrial Fapomed S.A. ITN – Instituto Tecnológico e Nuclea Project started: October 1998 Project ends: September 2002 Source of support: Convénio ICCTI/Embaixada de França Keywords: Non-active medical devices (medical textiles), Non-wovens, Protective clothing, Technical textiles
The Portuguese textile industry embraces all sectors, from the production of raw materials and spinning up to the garment industry, mostly conventional textiles, like home textiles and classic garments. The competition of other countries in East Europe, Asia, North Africa and other European countries, among them Greece and Turkey, is growing in these industries. Because of that we have to gain competitive advantages and consolidate new markets, namely in the technical textile sector and specifically in the health-care and hygiene market. It is essential that we conquer sectors in which it is possible to demonstrate our gain in quality, know-how and flexibility and the interest in producing a major diversification of innovative products to permit penetration in new markets. In the area of technical textiles, which is actually one of the three major fields of the textile industry, the area of protective fabrics is growing fast, because of the appearance of new fibres, processing and fabrication technologies. An important and growing part of the textile industry is the medical and related health-care and hygiene sectors. The extent of the growth is due to the constant improvements and innovations in both textile technology and medical procedures. Also, the range of products available is vast, but typically the use is either in the operating theatre or on hospital ward for the hygiene, care and safety of staff and patients. Since 70 per cent of these products are disposables from non-wovens, the research design and development must be a priority in this field.
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The manufacturers of these products used in the operation room present frequently the study of the properties from the material used before sterilisation, without knowing the changes which can appear after the sterilisation, namely in the comfort and barrier properties. Project aims and objectives This project will treat the surgical gowns – disposables used as medical devices in the health-care facilities – and has the following objectives: • study the properties of surgical gowns – disposables, before and after the submission to several low temperatures sterilisation methods; • study the influence of the sterilisation doses over the properties, to guarantee a maximum safety limit for surgical gowns; • study the influence of ageing through artificial ageing of the surgical gowns by means of elevated temperature with air; • study the different joining methods in the manufacturing of surgical gowns disposables and the possible changes after sterilisation; and finally • compare and quantify the influence of each sterilisation method over the used materials and indicate the most adequate sterilisation methods for each studied type of gown. Publications Araújo Marques, M.J. (1995), “A importância dos materiais de protecç˜ao no âmbito da indústria têxtil”, Seminário EUROTEX: Texteis Técnicos – Um Sector em Expans˜ao, Universidade do Minho, Guimar˜aes, Portugal, 10-11 July. Araújo Marques, M.J. (1998), “0 papel da subcomissão 5 – vestuário de Protecção”, Sessão de Esclarecimento sobre Marcação CE no Vestuário de Protecção, CITEVE, Famalicão, Portugal, 2 July. Araújo Marques, M.J. and Cabeço Silva, M.E. (1996a), “The mechanical properties of OR garment and surgical drapes – disposables – in the presence of adhesives used in the manufacturing”, Conference MEDICAL TEXTILES 96, Bolton Institute, Bolton, 17-18 July (poster). Araújo Marques, M.J. and Cabeço Silva, M.E. (1996b), “The properties of non-wovens in the health-care industry”, Conference TECNITEX, Turin, Italy, 21-23 November. Araújo Marques, M.J. and Cabeço Silva, M.E. (1997a), “Aplicações de têxteis hospitalares em Portugal”, 1 as Jornadas Têxteis e do Vestuário, Universidade do Minho, Guimarães, Portugal, 2-4 April. Araújo Marques, M.J. and Cabeço Silva, M.E. (1997b), “Performance requirements of medical textiles – single use materials”, Advances in Fibre and Textile Sciences and Technology, The Fiber Society Spring Meeting, Mulhouse, France, 21-24 April. Araújo Marques, M.J. and Cabeço Silva, M.E. (1997c), “The design of surgical clothing – application in the health-care and hygiene industry”, Conference TECNITEX, Turin, Italy, 1921 November. Araújo Marques, M.J. and Cabeço Silva, M.E. (1998a) “Propriedades e materiais têxteis relevantes nas aplicações médico-cirúrgicas”, II Jornadas Têxteis e do Vestuário, Universidade do Minho, Guimarães, Portugal, 22-24 April. Araújo Marques, M.J. and Cabeço Silva, M.E. (1998b), “Contribution to the definition of properties important for disposable OR garments”, 4. Dresdner Textiltagung 1998, Technische Universität Dresden, Dresden, Germany, 24-25 June.
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Araújo Marques, M.J. and Cabeço Silva, M.E. (1998c), “Aplicações de Têxteis Hospitalares em Portugal”, XVII Congresso Nacional dos Técnicos Têxteis, 5a Feira Nacional da Indústria Têxtil, Casa Grande – Guarujá, São Paulo, Brasil, 9-12 September. Araújo Marques, M.J. and Cabeço Silva, M.E. (1999), “New materials for medical and surgical applications (non-active medical devices)”, Materiais 99 Conference, Universidade do Minho, Guimarães, Portugal, 21-23 June. Araújo Marques, M.J., Cabeço Silva, M.E. and Cabeço Silva, A.A. (1997), “Design of medical textiles – application in the health-care industry”, The Fiber Society Autumn Meeting, Knoxville, USA, 20-22 October (poster). Araújo Marques, M.J., Cabeço Silva, M.E. and Cabeço Silva, A.A. (1998), “Multivariate analysis in the optimisation and modelling of the quality properties of surgical clothing”, CESA 98, Nabeul-Hammamet, Tunisia, 1-4 April. Araújo Marques, M.J., Cabeço Silva, M.E. and Cabeço Silva, A.A. (1999), “Environmental balance of medical textiles – disposables vs. reusables”, II Conferência Internacional Têxtil/Confecção, SENAIICETIQT, Rio de Janeiro, Brasil, 21-23 July.
Newcastle upon Tyne, UK University of Newcastle upon Tyne, Stephenson Building, The University, Newcastle upon Tyne NE1 7RU Tel: (0191) 222 7145; Fax: (0191) 222 8600 Professor P.M. Taylor, Department of Mechanical, Materials and Manufacturing Engineering Research staff: D. Pollet
Vibration of fabric panels and automated garment assembly Other partners: Academic Industrial None None Project started: 1 October 1992 Project ends: Keywords: Bending, Environment, Friction, Grippers The primary aim is to understand the way fabrics and garments interact with mechanical devices designed to hold them and move them around and how their behaviours are affected by environmental changes. Studies are being undertaken on an analysis of the behaviour of fabric during the pinch gripping operation and on how fabric panels move on vibratory surfaces. To complement this, the relevant properties of fabrics are being studied, particularly buckling, bending and friction under zero and low applied normal forces. Friction and bending tests are also being undertaken over a wide range of environmental conditions to see the effects of humidity changes on handling processes.
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Project aims and objectives The primary aim is to understand the way fabrics and garments interact with mechanical devices designed to hold them and move them around and how these are affected by environmental changes. Academic deliverables Gripping analysis – vibration analysis, new instrumentation, results showing strong links between handling behaviour and environmental conditions. Industrial deliverables None yet. Publications Taylor, P.M. and Pollet, D.M. (1996), “Why is automated fabric handling so difficult?”, 8th International Conference on Advanced Robotics (ICAR 97). Taylor, P.M., Pollet, D.M. and Griesser, M.T. (1994), “Analysis and design of pinching grippers for the secure handling of fabric panels”, Proceedings of Euriscon ’94, Vol. 4, Malaga, Spain, 22-26 August, pp. 1847-56.
Nottingham, UK Ellis Developments Limited, 68 Carlton Road, Nottingham NG3 2AP Tel: (0115) 958 8878; Fax: (0115) 911 0119; E-mail:
[email protected] Julian Ellis Research staff: Peter Butcher
Surgical implants using the techniques of embroidery (SITE) Other partners: Academic Industrial University of Nottingham Pearsalls Limited (Department of Vascular Surgery) Project started: September 1997 Project ended: January 2000 Finance/support: £316,000 Source of support: Department of Health (MedLink Scheme) Keywords: Textiles, Embroidery The objective of the project was to investigate the use of embroidery techniques for the manufacture of surgical implants. The project developed a technical demonstrator in the form of a graft stent for the repair of abdominal aortic
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aneurysms (AAA) using endovascular techniques. AAAs kill some 10,000 patients in the UK alone each year. The project used the demonstrator to show that fibre placement using embroidery could be applied not only to textile fibres using the CADCAM techniques of modern embroidery systems, but the placement of metallic shape memory alloy wire. Existing fibre placement techniques were developed through the use of software and stimulated development of associated methodologies and design techniques. In the rapidly moving world of endovascular surgery, a product requirement specification that changed throughout the project demonstrated that the technology could keep pace with the fast-changing demands of the surgeons. The project has also stimulated an enhanced understanding of the problems of endovascular techniques and an MD thesis is now in preparation as a result of an underlying programme to understand attachment of the endovascular graft stent to human aortae. Project aims and objectives To produce a validated method for the design and cost-effective production of low and medium volume production textile surgical implants. To develop a specific application in the area of vascular surgery, in order to demonstrate the technique. The project aimed to produce a set of design rules for embroidery of implants; to introduce a reproducible method of manufacture to meet the requirements of good manufacturing practice; and to develop manufacturing conditions and process appropriate to implant production. The method was validated through clinical tests. Achieved project deliverables (academic and industrial) • An understanding of the design rules for embroidered surgical graft stents. • An understanding of design rules for other textile surgical implants. • The development of validated manufacturing methods for the design and manufacture of custom-made implants. • A demonstration of extremely rapid prototyping and manufacturing speeds. • Structural design methods for embroidered textile reinforcement. • Demonstration for potential for embroidery as a method of manufacture of customisable surgical implants. • Manufacturing method for surgical implants which is highly flexible, has improved performance and has high consistency compared with conventional textile implant manufacturing techniques. • Established design control procedures.
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Established manufacturing control procedures. Apparently successful animal trials of the demonstration product. Apparently successful laboratory testing of the demonstrated product. Developed protocol and software design rules. Validated implant design. Product almost ready for submission to Medical Devices Agency.
Publications Ellis, J.G., Wallace, W.A. and Neumann, L. (1996), “Textile for the repair of the rotator cuff of the shoulder”, Medical Textiles, Bolton. Hopkinson, B.R. and Macierewicz, J. (1999), “What should we look for in the next generation of endovascular grafts?”, Proceedings of the 26th Annual Symposium on Current Critical Problems, New Horizons and Techniques in Vascular and Endovascular Surgery, New York, NY, November. Hopkinson, B.R., Macierewicz, J. and Beaton, G. (1999), “Combined interventional and surgical treatment of abdominal aortic aneurysms using nickel-titanium tubular grafts – an alternative approach”, Proceedings of the Medical Applications for Shape Memory Alloys, Seminar, 2 September. Conference presentations Ellis, J.G. (1999), “Surgical implants using embroidery techniques”, UK liaison committee for Sciences Allied to Medicine and Biology New Technology, 4th International Conference, Brunel. Ellis, J.G. (2000), “Engineering and surgical textiles by embroidery”, World Conference, The Textile Institute, Manchester, April. Ellis, J.G. and Hopkinson, B.R. (1988), “The endoscopic repair of abdominal aortic aneurysms using embroidered textiles”, Link Medical Implant Seminar, Meriden, UK. In preparation Macierewicz, J., “Study on the development of an embroidered prosthesis for endovascular repair of abdominal aortic aneurysms”, MD thesis. Exhibition Display at “Tomorrow’s World Live” Exhibition, NEC Birmingham, UK, July 1999. Patents PCT International Patent Application WO99/37242 “Reinforced Graft”. European Patent application “Device for the Reinforcement of the Rotator Cuff of the Shoulder”. US Patent 5990378 “Textile Surgical Implants”. European Patent Application 96303741.1 “Textile Surgical Implants”. European Patent 074416282 “Textile Surgical Implants”. US Patent 98/652316 “Textile Surgical Implants”, “Vascular Graft Stent”.
Ontario, Canada University of Guelph, Ontario, Canada, N1G 2W1 K. Slater, School of Engineering Research staff: various graduate students
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Protective clothing design for agricultural uses Other partners: Academic Industrial None None Project starts: April 1999 Project ends: April 2003 Finance/support: Applications under development Source of support: Various groups to be approached Keywords: Agriculture, Protective clothing The project depends on the ability of textile materials to be incorporated into designs of garments which can resist the ingress of harmful chemicals yet allow the escape of perspiration moisture. Preliminary design considerations have been established, but continuation of the work depends on the successful negotiation of adequate funding, a step which is currently in progress. Project aims and objectives The aim of the project is to develop a clothing system capable of providing agricultural workers with adequate protection from the various chemical and microbiological hazards which they continually encounter in their daily work. Academic deliverables One or more graduate theses. One or more journal articles. Industrial deliverables Protective clothing capable of preventing health deterioration in agricultural workers continually exposed to harmful chemical or microbiological hazards, with the added advantage of being comfortable enough for the workers to accept it without demur. Publications No publications stemming directly from this project have appeared to date, but some of my earlier work (e.g. protective clothing for operating room use) is relevant and has appeared in the past. I have also presented papers dealing with the need for protection of agricultural workers at several recent conferences.
Ontario, Canada University of Guelph, Ontario, Canada, N1G 2W1 K. Slater, School of Engineering Research staff: various graduate students
Protective clothing design for industrial use
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Other partners: Academic Industrial None None Project starts: April 1999 Project ends: April 2003 Finance/support: Applications under development Source of support: Various groups to be approached Keywords: Clothing, Industrial clothing, Protective clothing Industrial accidents frequently cause injuries which could have been prevented by the use of appropriate protective clothing. Flying projectiles, violent contact with machinery, vehicles or the ground, and exposure to harmful chemical or biological materials are encountered regularly in accident reports. This project is intended to build on my previous research in the degradative changes occurring in textiles, and on my comfort research, to match the protective needs of clothing intended to safeguard human beings from the hazardous conditions to which they are exposed. A major need is to ensure that wearers are not likely to discard the protective garments for reasons of physical or mental comfort, so that protection is abandoned. As the work is still in the planning stage, it is not possible to provide any detailed synopsis of its course. Project aims and objectives The aim of the project is to use textile materials, in conjunction with other components, to prevent (or minimise injury from) industrial accidents. Academic deliverables One or more graduate theses. One or more journal articles. Industrial deliverables Protective clothing capable of reducing or eliminating injury, and hence reducing financial costs, arising from workplace accidents. Publications No publications stemming directly from this project have appeared to date, but some of my earlier work relates closely to the needs of this research.
Pendleton, USA Clemson Apparel Research, 500 Lebanon Road, Pendleton, SC 29670-1957 Tel: 864-646-8454; Fax: 864-646-8230 Chris Jarvis, Steve Davis, Bill Kernodle Research staff: Wiboon Masuchun, Sivaram AngannaMuthu
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Decision support for balanced inventory flow replenishment system Other partners Academic None
Industrial Defense Supply Center, Philadelphia Parris Island Marine Base Finance/support: $80,000 (estimated portion of $512,605 contract devoted to this project) Source of support: Defense Logistics Agency Project started: 15 September 2000 Project ended: 15 September 2001 (renewable annually through 2002) Keywords: Clothing ordering and distribution, Supply chain, Decision support system This project addresses two problems that are important in effectively managing a supply chain for apparel. First, one must determine efficient choices for the target levels of inventory at various places in the chain and the sizes of transfer batches among different points in the chain. It is desirable to have enough inventory to avoid starving the resources that constitute system-wide constraints, but as little as possible elsewhere. Larger batch sizes help reduce setup costs but reduce system responsiveness. This project will develop a model and a solution method to calculate efficient choices for the inventory levels and transfer batch sizes. Because this problem is so computationally complex the project will probably employ a heuristic search. Second, effective management of a large supply chain requires careful choice of manufacturing resources, considering the trade-off between production cost and speed of response. Most of the production should be done on a high volume, low cost basis. But a certain amount of the available production capacity should be set up for quick response, higher cost production. When actual demand deviates from the forecast, the supply chain needs to be able to respond by changing (part of) the production plan rather quickly. Otherwise stock outages may occur for certain styles or sizes of garments. The question is, what percentage of the production should be rapid response? We will develop models for these problems, determine a solution method, and incorporate that solution in a decision support system. Sponsored by the US military, this project has broad application potential in private industry. Project aims and objectives This project will develop a decision support system for managing an apparel supply chain. The system will help support the following decisions: (1) how to optimize plans for buffer (inventory) and transfer batch sizes throughout the supply chain; and
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(2) selecting optimum mix of long cycle-time, low-cost manufacturing and quick response, high-cost manufacturing.
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Research deliverables For the academic community, this project will produce a detailed description of the new models and methods for calculating optimum settings for inventory levels and transfer batch sizes and the optimum percentage of production that should be rapid-response. For the military and industrial community, the project will produce a system capable of supporting decisions by the supply chain manager.
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Publications None as yet.
Pendleton, USA Clemson University, 500 Lebanon Road, Pendleton, SC 29670-1957 Tel: 864-646-8454; Fax: 864-646-8230 Jack Peck, Ramesh Kolluru, Steve Davis, Paul Meredith, Chris Jarvis, Stanford Smith, Bill Kernodle Research staff: Levent Camlibel, Wiboon Masuchun
Scalable information flow for the extended business enterprise Other partners Academic University of Louisiana at Lafayette
Industrial Rutter-Rex Apparel Mfg Co. Milliken Textiles Du Pont Performance Textiles, Inc. Performance Designs Defense Supply Center, Philadelphia Parris Island Marine Base Department of Energy
Finance/support: $198,573 Source of support: National Science Foundation Grant DMI-0075608 Project started: 15 August 2000 Project ended: 31 July 2001 Keywords: Supply chain, Enterprise resource planning, Sewn products This grant provides funding for the modeling, developing and prototyping of communication standards and interfaces that will support scalable, extended enterprise resource planning (EERP) systems. Based upon an examination of
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a set of existing supply chains, a general model will be developed to represent a supply chain and the data needed to support transactions within the chain. Standards based upon XML will be developed for communication interfaces in a supply chain consisting of links that receive products from many suppliers in the chain and create products for many customers in the chain. Models will be constructed for representing not only linear relationships of suppliers, manufacturers and customers (supply chains) but also complex relationships that can only be represented as two-dimensional directed graphs (supply networks). The prototype software will be designed, developed and tested to determine how well the model supports operation of a small, sewn products supply network with scalability to a complex of military sewn products such as apparel, footwear, and chemical protective suits. This research will lead to new features that are lacking in current enterprise resource planning systems because they focus on supporting internal operations of firms with common ownership or administration. Results of this project will influence the design of future EERP systems to incorporate business-to-business support for groups of co-operating, independently managed organisations – a virtual enterprise that builds competitive advantage through collaboration. Project aims and objectives This project will develop a general model that represents a supply chain and the data needed to support transactions within the chain, and establishes standards based upon XML for communication interfaces in a supply chain consisting of links that receive products from many suppliers in the chain and create products for many customers in the chain. The prototype software will be designed, developed and tested to determine how well the model supports operation of a selected small sewn products supply network and how easily it extends to a larger network. Research deliverables (academic and industrial) (1) Model of an information system that supports an extended enterprise (supply chain). (2) Standards for communication interfaces among participating firms. (3) Prototype software based on the model and standards. (4) Report of the model suitability for a sewn products supply chain and model extendibility. Publications None yet.
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Pendleton, USA Clemson University, 500 Lebanon Road, Pendleton, SC 29670-1957 Tel: 864-646-8454; Fax: 864-646-8230 Jack Peck, Ramesh Kolluru, Steve Davis, Paul Meredith, Chris Jarvis, Stanford Smith, Bill Kernodle, Clemson Apparel Research Research staff: Levent Camlibel, Wilboon Masuchun, Nithinant Thammakoranonta
Scalable information flow for the extended business enterprise Other partners Academic University of Louisiana at Lafayette
Industrial Rutter-Rex Apparel Mfg, Co. Milliken Textiles DuPont Performance Textiles, Inc. Performance Designs Defense Supply Center, Philadelphia
Finance/support: $198,573 Source of support: National Science Foundation Grant DMI-0075608 Project started: 15 August 2000 Project ends: 31 July 2002 Keywords: Supply network, Enterprise resource planning, Sewn products This project will develop a model and prototype software for a scalable, extended enterprise resource planning (EERP) system. Based upon an examination of a set of existing supply chains, a general model will be developed to represent a supply network (wherein each firm may have more than one customer and more than one supplier). Standards based upon XML will be developed for communication interfaces. The prototype software will be designed, developed and tested to determine how well the model supports operation of a small, sewn products supply network with scalability to a complex of military sewn products such as apparel, footwear, and chemical protective suits. This research will lead to new features that are lacking in current enterprise resource planning systems because they focus on supporting internal operations of firms with common ownership or administration. Results of this project will influence the design of future EERP systems to incorporate business-to-business support for groups of cooperating, independently managed organizations – a virtual enterprise that builds competitive advantage through collaboration.
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Project aims and objectives This project will develop a general model of a supply network and prototype software for supply network management. The model will include standards for transactions and for data sharing within the network. The prototype software will be designed, developed and tested to determine how well the model supports operation of a selected small sewn products supply network and how easily it extends to a larger network. Research deliverables (academic and industrial) (1) Model of an information system that supports a supply network (completed). (2) Prototype software based on the model and standards (completed). (3) Standards for communication interfaces among participating firms. (4) Report of the model suitability for a sewn products supply chain and model extendibility. Publications Kolluru, R., Meredith, P., Steward, A., Smith, M., Smith, S., Dwivedi, S., Peck, J. and Davis, S. (in press, 2001), “An extended enterprise framework for supply network management”, International Journal of Agile Manufacturing, Vol. 3 No. 2. Peck, J., Kolluru, R., Davis, J., Kernodle, B., Jarvis, C., Pargas, R., Steward, A., Smith, M. and Smith, S. (in press, 2001), “Information support for supply network management”, The International Journal of Agile Manufacturing, Vol. 3 No. 2. Pargas, R., Jarvis, C., Davis, J., Peck, J., Kernodle, B. and Luo, W. (in press, 2001), “DSS improves supply chain operations”, Issues in Information Systems. Luo, W., Davis, J. and Peck, J. (2001), “Timing control in discrete event simulation”, IIE Solutions, Vol. 33 No. 5, May, pp. 32-6.
Pendleton, USA Clemson University, 500 Lebanon Road, Pendleton, SC 29670-1957 Tel: 864-646-8454; Fax: 864-646-8230 Jack Peck, Steve Davis, Chris Jarvis, Nithinant Thammakoranonta, Tyson Wilson Clemson Apparel Research
New approaches to the tentative order commitment decision in a supply network Other partners Academic None Finance/support: $12,600
Industrial None
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Source of support: National Science Foundation (Supplementary) Grant DMI-0075608 Project started: 15 August 2000 Project ends: 31 July 2002 Keywords: Ordering, Order commitment, Supply chain management This project will investigate the state of the practice and will develop and evaluate a new automated protocol for making the tentative order commitment decision in a supply network having multiple suppliers for the same item. (When a customer seeks to place an order with a firm, that firm must decide whether it can commit to satisfy it.) Making this decision promptly and accurately is important to the efficiency of supply network operations, increases customer satisfaction, and helps suppliers manage their inventories and production more effectively. Because there is no evidence in the literature that any firms use a formal, automated methodology to make this tentative order commitment decision, it appears our developing a new automated protocol could be a major benefit. We will investigate the state of the practice in making this decision using a mail survey and interviews of experts. Knowledge we gain about the state of the practice will help calibrate the protocol and will help determine how to transfer the new technology to industry. The new protocol will be based upon the two-phase commit protocol that guarantees the integrity of a global transaction in distributed computer systems, because the tentative order commitment decision resembles a global transaction in many ways. We will evaluate the protocol with reviews by experts in supply chain management and by demonstration through scenarios that it works correctly in any possible supply chain situation or sequence of events. Project aims and objectives This project will determine the state of the practice in making the tentative order commitment decision and will develop and evaluate a new automated protocol for making this decision. The new protocol will provide a basis for software that quickly and accurately makes this decision in a supply network. Research deliverables (academic and industrial) (1) This project will produce a report of the state of the practice in making the tentative order commitment decision. It will be based upon analysis of results of a mail survey sent to 1,000 randomly selected members from the North American Purchasing Management (NAPM), excluding academic members. The survey instrument has been completed. (2) Also it will develop an automated protocol for the tentative order commitment decision that will handle a variety of policies for requesting a commitment, including: request from single supplier per item, distribute request among multiple suppliers with no overbooking, and distribute request among multiple suppliers with overbooking. (Overbooking means more items are requested than are needed; only the
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needed amount will be confirmed after selecting the best supplier offers.) A draft of this protocol has been completed. Publications None yet.
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Pendleton, USA Clemson University, 500 Lebanon Road, Pendleton, SC 29670-1957 Tel: 864-646-8454; Fax: 864-646-8230 Roy Pargas, Chris Jarvis, Bill Kernodle, Dawn Robertson, Jason Howell, Steve Davis Clemson Apparel Research
Balanced inventory flow replenishment system Other partners Academic Industrial None Parris Island Marine Base Finance/support: $500,000 Source of support: Defense Logistics Agency Project started: 1 October 2000 Project ended: 31 November 2001 Keywords: Supply network, Flow system, Sewn products This project is developing concepts and software for establishing a balanced flow of products through a supply chain. It extends an earlier system that focused on ordering decisions of a single firm. The new system will recommend ordering, production and distribution actions that benefit the overall supply chain. It is especially well suited for the sewn products industry, wherein the same type product is made in different sizes and colors and the challenge is to maintain the right balance among the different sizes and colors. However it could be applied more generally. Primarily it is concerned with maintaining balanced, user-specified levels of inventory in the critical buffers in the supply network. Therefore it measures inventory in days-of-supply rather than number of items. A prototype of this system has been tested successfully for recruit clothing at the US Marine Corps base at Parris Island, South Carolina. It will be tested on a private industry supply chain for sewn products. Project aims and objectives This project will develop software for establishing a balanced flow of products through a supply chain. The software may be used to manage product flow through segments of a supply chain or to manage an entire supply chain.
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Research deliverables (academic and industrial) The main industrial deliverable is software that supports management of a segment of a supply network or an entire network (prototype completed). The main academic deliverable is a report of the balanced flow concepts and of the field experience in applying the software to an actual supply chain.
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Riga, Latvia Institute of Textile and Clothing Technology, Riga Technical University, Latvia Prof. Dr habil sc. ing, Austrums Klavins Research staff: Assoc. Prof. Dr habil sc. ing, V. Priednieks, Lecturer I. Ziemele, postgraduate (Master and doctoral study programs) students
Control, optimisation and monitoring of the stitch formation process in sewing machines Other partners: Academic None
Project started: 1969 Finance/support: N/A Source of support: N/A Keywords: Sewing machines, Stitch
Research register
Industrial Company “Promshveymash” Orsha, Byelorussia (1969-1991) Sewing Company “Latvia” from 1991 Project ends: no limit
Effective operation of sewing machines is of crucial importance for the qualitative production of sewn goods. It is possible to attain it by improving the mechanisms of the machine, controlling and monitoring them. These problems are being solved by applying mathematical methods of statistics, theory of probability and experimental design. The research is based on the unconformity of interaction of stitch formation tools (mechanisms) and needle thread as a complex parameter which permits one to estimate the process as a whole in each cycle and to simulate this process. It allows one to find out the impact of separate mechanisms, to improve the quality of the stitch formation process, so that it is possible to control, optimise and monitor them. On this basis the sewing machines are modernised or rationally used in mass production lines.
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Project aims and objectives •
To work out the investigation methods of the sewing machine process.
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To develop methods of the basic, complex parameters control, optimization and monitoring.
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To develop practical methods for increasing the sewing machine’s serviceability, improving separate mechanisms of the machine.
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To work out methods for the selective application of sewing machines for a rational organization of mass production lines in the garment industry.
Academic deliverables •
The following part of the study programs for Master’s has been worked out, namely, control and monitoring of the sewing machine process.
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The results of the research have been used by doctoral students acquiring investigation methods.
Industrial deliverables •
Control, monitoring and improving the quality and serviceability of sewing machines.
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Rational organization of garment mass production lines.
Publications Aizpurietis, A.V., Klavins, A.R., Poluhin, V.P. and Sharamet, U.I. (1988), “Raschot chetirjohzvennogo mechanizma nitepritjagivatelja shvejnih machin na EVM”, Journal Tehnologia logkoi promishlennosti, Moscow, Vol. 6, pp. 94-7. Klavins, A. and Priednieks, V. (1998), “The quality improvement problems of the operation sewing machines and the prospects of the development of scientific research”, Scientific Conference of “Technologies and Design of Consumer Goods”, Kaunas University of Technology, 21-22 April. Klavins, A.R., Salenieks, N.K. and Rachok, V.V. (1974), “Diagramma ispolzovanija igolnoi niti”, Machinostrojenie dija logkoi promishlennosti, Moscow, No. 3, pp. 3-7. Olshanskij, V., Fedoseyev, G. and Klavins, A. (1987), “Raschot parametrov prushinih kompensatorov shvejnih mashin”, Journal Tehnologia logkoi promishlennosti, Moscow, Vol. 4, pp. 114-15. Priednicks, V. and Klavins, A. (1997), “The optimization of lockstitch formation system in sewing machines”, The 78th World Conference of The Textile Institute in Association with the 5th Textile Symposium of SEVE and SEPVE, Vol. 11, Thessaloniki, Greece, pp. 195-204. Some Adjusting Techniques for Sewing Machines, Pat (USSR) 442252. IPCl D 05 B 69/24. The Method for Plotting Needle Thread Take-up Curve, Pat (USSR) Nr. 324322 IPCI. D. 05 B45/00. The Method for Plotting Needle Thread Take-up Curve, Pat (USSR), Nr 461189 IPCl. D. 05 B45/00. Ziemele, I., Klavins, A. and Priednieks, V. (1997), “Selection of lockstitch sewing machine obtaining a high quality of thread joints in garment”, abstract of the papers presented at the 26th Textile Research Symposium at Mt Fuji, Shizouka, Japan, 3-5 August, pp. 60-3.
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Riga, Latvia Institute of Textile and Clothing Technology, Riga Technical University, Latvia Prof. Dr habil. sc. ing. Viktoria Kancevicha Research staff: Prof. Dr habil. sc. ing, V. Kasyanov, Assoc. Prof. Dr sc.ing. H. Vinovskis, postgraduate (Master and doctoral study programs) students
Development of new textile technology for manufacturing hybrid textile vascular grafts Other partners: Academic Latvian Medical Academy Project started: 1980 Finance/support: N/A Source of support: N/A Keywords: Technology, Textiles
Industrial None Project ends: no limit
In the fields of medicine and bioengineering extensive efforts have been directed to the development of various new types of vascular grafts using different technologies. The textile industry has a lot of practical experience in the production of different kinds of vascular grafts and allows a high production rate to be reached. Nevertheless there are practical needs for compliant grafts for patients with cardiovascular disease. Clinical implantation and chronic experiments on animals with various grafts have indicated a fairly good correlation between their compliance and patency (especially for a diameter less than 6mm) because the compliance vascular graft practically does not change the haemodynamics of the blood flow. Thus compliant vascular grafts having mechanical properties matching the human arteries are very promising for successful reconstruction operation and good patency. This problem of developing new textile technology and producing compliant vascular grafts is very important for Latvia because cardiovascular disease is very high – and not only in the Baltic states. The investigation of the peculiarities of the mechanical behaviour and structure of human blood vessels is carried out at RTU. On this basis the new structure of the hybrid textile materials is developed. Using the system of two threads having substantially different modulus of elasticity, it is possible to model peculiarities of the biomechanical behaviour of the arterial tissue. Project aims and objectives • Development of the new textile technology for manufacturing novel hybrid compliant vascular grafts using knowledge of the biomechanical properties and structure of human arteries.
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Manufacturing of novel compliant hybrid vascular grafts with biomechanical properties matching the host arteries.
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Establishing the new principles of the manufacturing of the hybrid material composed of two different types of threads for creation of the reinforced composite structure applicable to different engineering purposes. As expected, these structures will provide unique properties and will be characterised by improved reliability and durability.
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Academic deliverables •
The part of the study Masters program in textile technology has been worked out.
•
The methods and results of the research have been used in Doctoral study programs.
Industrial deliverables The new textile technology for manufacturing novel hybrid compliant vascular grafts. Publications Chnourko, M. and Kancevich, V. (1998), “Woven textile biomaterials international conference”, Textiles Engineered for Performance, UMIST, Manchester, 8-11 July. Kancevicha, V. and Kasyanov, V. (1994)., “Small diameter blood vessel prostheses”, Fibres and Textiles in Eastern Europe, Vol. 2 No. 3, pp. 32-3. Kancevicha, V. and Kasyanov, V. (1996), “Crimp vascular graft”, Latvian Patent, Nr. 10836. Kancevicha, V. and Kasyanov, V. (1998), “Crimp vascular graft”, Latvian Patent, Nr. 12175. Kasyanov, V., Purinya, B. and Kancevich, V. (1994)., “Compliance of human blood vessels and novel textile vascular grafts”, Abstracts of Second World Congress of Biomechanics, Amsterdam, The Netherlands, 10-15 July, Vol. 1, p. 28. Kasyanov, V., Kancevich, V., Purinya, B. and Ozolanta, I. (1996), “Design of biomechanically compliant vascular grafts”, 10th Conference of the European Society of Biomechanics, Leuven, 28-31 August, p. 26. Kasyanov, V., Kancevich, V., Purinya, B., Izolanta, I. and Ozols, A. (1998), 1st Conference of the European Society of Biomechanics, Toulouse, 8-11 July.
Riga, Latvia Institute of Textile and Clothing Technology, Riga Technical University, Latvia Associate Professor, Dr sc. ing. Ivars Krievins Research staff: Msc, Dipl. ing V. Sorokins, Msc Dipl. ing S. Valaine, postgraduate (Master and doctoral study programs) students
Latvian clothing market product oriented research
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Other partners: Academic Terminology Committee of Academy of Sciences
Industrial Ministry of Light Industry of Latvia (1988-89) Ministry of Economics of Latvia (1997-98) Lauma Co., Liepaja, Latvia (1996-97) Project started: 1988 Project ends: no limit Finance/support: for particular objectives Source of support: N/A Keywords: Clothing, Fashion
General long-term Latvian clothing market studies embrace common information areas met through market secondary (desk) research. Mainly it is based on the analysis of the Latvian 8000 household budget survey data and others available, e.g. pricing statistical data. The results of the Latvian clothing market general monitoring are oriented towards use in academic and industrial fields. In addition, the results are used for planning of primary clothing market research within a narrower in-depth range of clothing products. The morphological structure of ladies’ underwear demand has been determined by the studies of catalogues, that of corresponding retail outlets and by administering questionnaires to 300 respondents on their actual and planned underwear wardrobe in 1997. In order to carry out the inquiry, Latvian/Russian terminology has been developed for naming illustrated product characteristics of the questionnaires. An elaborated thesaurus of clothing production terms is included in wider consumer education programmes as well as in the academic and professional ones. Conceptual analysis can be used for coordination and subordination of the educational contents within different levels and sectors of clothing education. Project aims and objectives • General monitoring of Latvian clothing market size and segmentation trends. • Distribution of consumer preferences by morphological attributes within in-depth analysis of clothing products. • Simulation of the garment quality evaluation based on consumer perception/satisfaction analysis. Academic deliverables • Morphological simulation of clothing product differentiation. • Comprehensive clothing quality evaluation methodology. • Mathematical simulation of clothing sizing.
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Dictionary of Latvian/Russian clothing terms as the basis for product information processing.
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General information on Latvian clothing market. Particular information on the women’s underwear style preferences in Riga, 1997. Feasibility of textiles and clothing standardization items in Latvia.
Publications – – Blinkens, P., Be– zina, V. and Krievins˘ , I. (1989), Tekstilru pniecı- bas terminu vardnı ca, Zin–atne Riga, 855 lpp. (Dictionary of 14,000 textile terms). Der lettische Textil- und Bekleidungsmarkt = LR tekstiliju un apgerbu tirgus – Riga (1997), 57 S. (German/Latvian: Latvian textiles and clothing market, Desk research). Krievins, I. (1996), “Systematization of clothing technology concepts for Latvian terminology”, (Lengvsios pramones tehnologios ir dizainas), Kauno, pp. 221-8. “Rigas sievies˘ u apaks˘ g` e– rbu pieprası- juma struktu– ra” (1997), gad a–, ZPD pa– rskats; Riga, 97,1p (Structure of ladies’ underwear demand in Riga).
Riga, Latvia Institute of Textile and Clothing Technology, Riga Technical University, Latvia Prof. Dr habil sc. ing, Silvia Kukle Research staff: Assoc. Prof. Dr sc. ing, A. Vilumsone, Lecturer I. Vilumsone, Postgraduate (Master and doctoral study programs) students
The investigation of the geometry and composition of Latvian folk art designs Other partners: Academic Latvian Council of Science 1989-1996 Project started: 1989 Finance/support: N/A Source of support: N/A Keyword: Textiles
Industrial Latvian Crafts Chamber, 1993-present Project ends: No limit
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Folk art is the form of ethnic consciousness to consolidate not only people of one nation but also of many generations. It is a means for manifesting and forming the specific face of the country and investment in the worldwide cultural heritage. We started our work on computerized collections in 1989, involving scholars of our university and many generations of students. As a result, material from museum and private collections and published works were collected together and systematized and presentations were prepared. The data address different users and applications, such as teaching materials to support school and university courses such as home economics, crafts technologies, ethnography ornamentation and composition; teaching materials for craftsmen for use in design studies libraries to support reproduction for local users – householders, artists and tourist markets; as a source of ideas – motifs and symbols, technologies, ways of material combination with different properties, fashions, placement of ornamentation, compositional solutions, creation of motifs, methods of designing double-face ornamented fabrics, pattern designing; methods of forming color ranges; leveraged space filling; fantasy for imagination. The other application is a well organized source of multipurpose scholastic studies, for example, to sort and classify, to study decoration methods and/or technologies, to find out rules; ethnographic studies, historical studies; regional studies; ethnoastronomy studies, linguistic studies. Project aims and objectives Aim: creation of the computerized knowledge basis of Latvian folk designs, crafts, technologies and tools. Objectives: creation of the image and text libraries for different groups of folk textiles (mittens, table cloths, towels, girls’, women’s and men’s folk costumes, blankets), woodwork tools; investigation of basic rules followed in forming motifs, symbols, compositional groups and composition; investigation of the colour, symbol preferences in different regions and products; comparative analysis of ornamentation traditions in Latvian and Lithuanian folk art; analysis of the information structure and creation of the codification system; calculation of data leading system. Academic deliverables New knowledge supplementing basics of Latvian folk art; creation of new methods of investigation; creation of databases for further investigations; investigation of the use of prehistorical symbols and signs in Latvian border patterns, comparison with other ancient cultures; creation of the system of hypothesis; highly systematized teaching materials supporting different study courses. Industrial deliverables Methods of motifs’ creation, organization of rhythms, color ranges, border and panel type compositions; methods of creation of two face fabric designs; library
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of designs for reproduction (crafts companies, crafts people, students) and as an inspiration for new designs (artists, craftsmen, designers, students), knowledge of folk art basics (artists, craftsmen, designers, technologists). Publications Kukle, S. (1993), Geometry of Latvian Designs, thesis of Dr habil ing dissertation, Latvia. Kukle, S. (1995), Geometry of the Crosses and Diamond Type Signs Preferably Used in Latvian Folk Designs. The Investigation and Optimization of the Textile Technology, Riga, Latvia, pp. 67-78. Kukle, S. (1996), “Computer graphics as a tool giving unambiguous results”, poster abstracts, 2nd World Congress on the Preservation and Conservation of Natural History Collections, University of Cambridge, 20-24 August. Kukle, S. (1997), “Latvian border patterns, Lengvosios pramones technology”, Kauno tecgnologijos universitetas, Lithuania. Kukle, S., Vilumsone, A., Vilumsone, I. and Kikule, D. (1996), “Database of Latvian folk designs”, poster abstracts, 2nd World Congress on the Preservation and Conservation of Natural History Collections, University of Cambridge, 20-24 August. Vilumsone, I., Kukle, S. and Zingite, I. (1995), “The ornaments and rhythms of sashes of Alsunga (town on Western Baltic seaside)”, The Investigation and Optimization of the Textile Technology, Riga, Latvia, pp. 54-60.
Riga, Latvia Institute of Textile and Clothing Technology, Riga Technical University, Latvia Tel: 00371 708 9333 Assistant Professor Ilze Baltina, Department of Mechanical Technology of Fibre Materials Research staff: Assistant Professor I. Brakch, Associate Professor H. Vinovskis and postgraduate students
Wool carbonizing in the radio frequency electromagnetic field Other partners: Academic None
Industrial Textile factory at Kustanai (Kazakhstan) 1992-present Textile factory at Cernigov (Ukraine) 1993-1995 Textile factory “Riga tekstils” (Latvia) 1991-1994 Project started: 1989 Project ends: no limit Keywords: Electromagnetics, Radio, Wool
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In wool carbonizing the baking process is usually carried out at very high temperatures, 120-125˚C, but sometimes also at 130˚C. At such temperatures wool decomposes and turns yellow. It is advanced by a high concentration of sulphuric acid solution. In the new method, instead of baking with hot air, there is inclusion of radio frequency electromagnetic field, which creates vegetable matter energy that is extracted as heat. Wool temperature does not exceed 100˚C and end moisture is 10-15 per cent, but vegetable matter temperature is sufficient for hydrolysis. Sulphuric acid concentration in this case does not exceed 35-40 per cent. Wool fibre rapid hydrolysis and dissolution occurred when the acid concentration ranged from 40 per cent up. Project aims and objectives To work out new carbonizing technology in which vegetable matter can be removed maximally, but wool fibre damage is very low. Academic deliverables Practice and new knowledge for Master’s and postgraduate students. Industrial deliverables New carbonizing technology which prevents wool damage during carbonizing. Publications Baltina, I. and Brakch, I. (1997), “Wool carbonizing in a radio frequency electromagnetic field”, World Textile Congress on Natural and Natural-Polymer Fibres, University of Huddersfield. Baltina, I. and Reihmane, S. (1998), “Use of cellulose production waste product lignosulphonate in carbonisation of wool”, 7th International Baltic Conference on Materials Engineering, Jurmala, Latvia, pp. 161-5. Zarina, I. (Baltina, I.), Reihmane, S., Braksch, I. and Liepa, I. (1995), “Wool carbonizing methods”, Progress in New Polymer Materials: Seminar Materials of TEMPUS Programme, Riga.
Selkirkshire, Scotland Heriot-Watt University, Netherdale, Galashiels, Selkirkshire, Scotland Tel: 01896 892136; Fax: 01896 758965 E-mail:
[email protected] School of Textiles Xiaogang Chen, Prasad Potlouri, Tilak Dias, Department of Textiles, UMIST; Samir Mukhopadhyay, Steven Russell, Cherian Iype, Palitha Bandara, The School ot Textiles, University of Leeds; George Stylios, Bert Mather, Bob Christie, Dean Robson, The School of Textiles, HeriotWatt University
Engineering the performance and functional properties of technical textiles
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Other partners: Academic Industrial UMIST British Textile Technology Group University of Leeds Industrial Member companies Project started: 1 September 2001 Project ends: 31 August 2004 Finance/support: £1,000,000 Source of support: Department of Trade & Industry Engineering and Physical Science Research Council Keywords: Industrial textiles, Non-woven, Biomedical, Fibres, Yarns, Fabrics, Garments Technical textiles are defined as textile materials and products manufactured for their technical performance and functional properties rather than their aesthetic and decorative characteristics. Despite market predictions for technical textiles, and incremental advances in some companies, many fundamental problems relating to the engineering and development of technical textiles remain to be solved; these become more urgent due to fierce global competition. There are many areas that still employ subjectivity and tradition that hinder the leap forward the sector needs to enable the development of new products and applications of textiles as engineered materials. Structural mechanics of textiles has been researched extensively, focusing on the understanding of simple textile structures mainly for apparel applications. Whilst such research may have solved specific problems, there are serious limitations to the production of generic solutions for precision engineering and manufacture of technical textiles, due to the inherent complexity of technical textile materials and their structures. Limited research has been carried out on the engineering of other properties such as thermal and fluid, which are equally important for the engineering of technical textiles. Consultation within the academic community, and with industrial members of the TechniTex Partnership over the past 12 months has established three key themes of research required to enable the proposed underpinning platform of knowledge to be established. These mutually dependent themes are modelling (to enable 3D design, simulation, and visualisation), measurement (to define and understand the relationships between structure, performance, and functionality), and manufacture (to enable appropriate manufacturing conditions to create the engineered textile). Within each a fundamental understanding of materials is required. The three themes are reflected in the technical textile challenges. To ensure the industrial relevance and applicability of the theme-based research proposed, it is not possible to explore each theme in isolation. As shown above the level of mutual dependency requires that an integrated programme of research be conducted.
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Project aims and objectives The rapidly growing technical textiles industry draws ideas and expertise from a diverse range of academic groups and disciplines. The aim of the TechniTex core research programme is to formalise and extend this distributed generic body of knowledge relating to textiles. This extended and integrated body of knowledge will generate a platform for the creation of methodologies for specification, design and manufacture of technical textiles, and relate performance and functionality with manufacturing processes. The specific objectives are to: • establish databases of existing technical textiles, associated technical data, and the associated body of knowledge; • classify existing technical textile structures on the basis of their function, properties, and end use; • classify processing conditions for fibres, yarns, and fabrics; • identify missing data in terms of structural and mechanical detail, and fibre and yarn properties; • research and develop new and enhanced test methods and equipment for technical textiles; • generate new data to further establish the body of knowledge on existing yarns, fibres and fabrics; • establish the performance criteria necessary for technical textiles appropriate to their end use; • create geometric and mechanical models of technical textile structures using the derived classification and data; • create predictive models for these processes specific to the demands of technical textiles, and to optimise their manufacturing conditions to fulfil the specified performance criteria; • conduct an experimental programme for the verification of the models; • create interfaces between the models and generate an integrated suite for the engineering of technical textiles; • conduct a programme of dissemination and technology transfer through established TechniTex Faraday practices. Research deliverables (academic and industrial) • an integrated suite of databases encapsulating the body of knowledge on technical textiles; • geometric models for visualisation and input into performance modelling; • mechanical models for performance and manufacturability; • new and enhanced test methods and equipment;
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new standards for the specification and manufacture of technical textiles; methodologies for the creation of engineered technical textile structures; methods for optimising manufacturing conditions, processes and materials geared to the specific needs of these engineered structures; a technology transfer pathway through to the wider industrial and academic networks of the TechniTex Partnership.
Publications Russell, S.J. and Mao, N. (2000), “Directional permeability in homogeneous nonwoven structures. Part 2: permeability in idealised structures”, J. Text. Inst., Vol. 91, pp. 344-58. Bandara, P. and Islam, S. (1991), “Yarn spacing measurement in woven fabric with special reference to start-up marks”, J. Text. Inst., Vol. 87, Part I, pp. 107-19. Finn, J.T., Sagar, A. and Mukhopadhyay, S.K. (2000), “Effect of imposing a temperature gradient on moisture vapour transfer through water resistant breathable fabrics”, Tex. Res. J., Vol. 70 No. 5, pp. 460-6. Partridge, J.F., Mukhopadhyay, S.K. and Barnes, J. (1998), “Dynamic air permeability behaviour of Nylon66 air bag fabrics”, Text. Res. J., Vol. 68 No. 10, pp. 726-31. Potluri, V.V.P., Atkinson, J. and Porat, I. (1992), “Performance assessment of a robot for use in a fabric test cell”, 29th International Matador Conference, Manchester, April.
Selkirkshire, Scotland Heriot-Watt University, Netherdale, Galashiels, Selkirkshire, Scotland Tel: 01896 892136; Fax: 01896 758965 E-mail:
[email protected] School of Textiles Professor G.K. Stylios Research staff: Ms Fan Han
HOMETEX: a virtual trading centre for textiles Other partners: Academic None
Project started: 1 September 2001
Industrial OCF Ltd Silicon Graphics Inc. Scottish Enterprise Borders Scottish Textiles Manufacturers Association Borders Textile Forum Project ends: 31 August 2004
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Finance/support: £1,000,000 Source of support: EU ERDF Objective 2 Keywords: Drape, Augmented reality, Virtual trading, Home shopping, 3D simulation, Dynamic draping In recent years we have witnessed a revolution in networking of information on a global scale via the Internet. Many companies have capitalised on this provision and have used it in many diverse ways, from electronic mailing to marketing, selling and trading of products and services. Marketing and selling of limp products such as textiles and, particularly, garments using new multimedia techniques would be extremely beneficial to the industry, since it would enable companies to reduce product to market, to enhance product development through 3D visualisation and to trade directly without the intervention of retailers. But selling of garments is not as easy as selling other commodities; garments are made of limp materials which take up the configuration of the wearer; customers would in most cases like to wear the garment, or, in the case of buyers, see the garment worn by a model. For the effective exploitation of these possibilities, we should, therefore, develop a multimedia environment to enable the simulation of drape behaviour of garment designs on virtual models who may resemble real customers. The textile industry chain, being a traditional industry, is very conservative in the use of multimedia for manufacture, advertising and/or sales. The reason is firstly because the industry consists of small companies which do not have the resources to use multimedia technologies effectively without training, and secondly there is not technological infrastructure available to realistically visualise new products from home. This project aims to pilot such possibilities which have other benefits to this industry in terms of “just-in-time” manufacture, 3D visualisation of new products and better communication with their customers. Project aims and objectives The main objectives of this scheme are as follows: • To develop a virtual Home Trading Centre for the textile, clothing and retailing industries: “HomeTex”. • To enable the production of virtual fashion shows for buyers through CD-ROM and Internet presentations. • To network 40 companies with 500 homes (directly) via the technology and to regularly upgrade and manage company trade data, for piloting the technology. • To establish and provide through “HomeTex” other trade data, real-time electronic mail, Tele Trading and, possibly, banking. • To enable textile and clothing companies to interface with this technology so that new products can be made much faster and to minimise energy, raw materials and other resources. • To network with other services, such as Cyber Tex and SPIN.
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Research deliverables (academic and industrial) A Virtual Trading Centre in Textiles operating from the Borders of Scotland. Publications Stylios, G.K. and Wan, T.R. (1998), “A new collision detection algorithm for garment animation”, International Journal of Clothing Science and Technology, Vol. 10 No. 1 pp. 38-49.
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Stylios, G.K. and Zhu, R. (1998), “The characterization of static and dynamic drape of fabrics”, Journal of the Textile Institute, Vol. 88 No. 4, pp. 465-75. Stylios, G.K., Wan, T.R. and Powell, N.J. (1996), “Modeling the dynamic drape of garments in synthetic humans in a virtual fashion show”, The International Journal of Clothing Science and Technology, Vol. 8 No. 3, pp. 44-55. Stylios, G.K., Wan, T.R. and Powell, N.J. (1995), “Modeling the dynamic drape of fabrics on synthetic humans; a physical lumped parameter model”, International Journal of Clothing Science and Technology, Vol. 7 No. 5, pp. 10-25.
Sofia, Bulgaria University of Chemical Technology and Metallurgy, Blv. “Kliment Ohridiski” 8, 1756 Sofia, Bulgaria Tel: 359 2 6254 367; Fax: 359 2 685488; E-mail:
[email protected] Dr D. Pishev, Department of Textile Chemistry Research staff: Dr S. Veleva and Dr A. Georgieva
Physiochemical aspects of the phase and structural changes in the system disperse dye-polyester-cellulosic substratum by the thermosolic method of dyeing Other partners: Academic Industrial None None Project started: 1996 Project ended: 2000 Finance/support: Not cited Source of support: National Fund for Scientific Research of the Republic of Bulgaria Keywords: Acceleration, Chemical reactions, Cotton, Dispersions, Dyes This project investigates the processes proceeding in the complex heterogenic system disperse dye-polyester-cellulose substratum in the presence of the previously unused combination of caprolactam and polyethylenglycol, additives suggested by the authors. To solve the problem, the possibilities of the physiochemical approach are used, which allows the processes of the changing of the investigated systems in the thermosolic dyeing conditions to be characterised. The probable alterations in the phase state of the disperse dye and the
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structure of the textile substratum are explored with the suitable instrumental methods: refractometry, spectrophotometry, UR-spectroscopy, NMR (nuclear magnetic resonance), Rho-diffraction and others. By the end of the project, scientific results are expected, concerning the physiochemical nature of the processes proceeding in the system disperse dyepolyester-cellulose substratum, under the mentioned conditions. These results will be helpful to the rationalisation of the processes of the dyeing of cottonpolyester blends. In this way, economic and ecological effects will be achieved which will be expressed in brighter colours of the textile materials, due to the increased amount of the fixed dye on the fibre, and significant decreasing of the dye in the effluent. Project aims and objectives The purpose of this project is to investigate the processes proceeding in the complex heterogenic system disperse dye-polyester-cellulose substratum in the presence of a previously unused combination of caprolactam and polyethylenglycol, additives suggested by the authors. Academic deliverables The solving of this problem can clarify the action of the previously unused combination of additives on the process of thermosol dyeing of cotton/polyester blends with disperse dyes. Industrial deliverables Suggested intensifiers make possible the one-bath process of dyeing of polyester/cotton textile materials with disperse dyes. Publications Georgieva, A., Pishev, S. and Veleva, S. (1996), “Dyeing of PE/CO fabrics with disperse dyes by thermosol method”, Finishing of Textile and Knitted Article Symposium, Plodiv, 10 October. Georgieva, A., Veleva, S. and Pishev, S. (1998a), “Kinetics of fixing of disperse dyes with dyeing CO/PE using the thermosol method”, Vlakna a Textil, Vol. 5 No. 1/2, pp. 2-5. Georgieva, A., Veleva, S. and Pishev, S. (1998b), “Influence of the intensifiers on the equilibrium by dissolution of disperse dyes in water”, Textil t obleko, Vol. 47 No. 9. Veleva, S., Georgieva, A. and Pishev, S. (1998), “Thermodynamic of fixing of disperse dyes by dyeing CO/PE by thermosol method”, Textil t obleko, Vol. 46 No. 1, pp. 17-18. Veleva, S., Georgieva, A. and Pishev, S. (no date), “Kinetic study on dissolution of dispersed dyes in the presence of intensifying additives”, JSDC.
Zagreb, Croatia Faculty of Textile Technology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia Prof. Dr Ruz˘ ica C˘unko, Department of Textile Chemistry and Testing of Materials Research staff: Dr Maja Andrassy, Dr Emira Pezelj, Dr Mirjana Gambiroz˘a-Juki´c, Vera Fris˘c˘ i´c, Biserka Vuljani´c, Antoneta Tomljenovi´c, Marija Kovac˘ evi´c
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Ecological aspects of fiber properties and quality of textiles Other partners: Academic Industrial None None Project started: 1 June 1997 Project ends: – Finance/support: N/A Source of support: Ministry of Science and Technology of the Republic of Croatia Keywords: Ecology, Textiles Research activities proposed are related to the environmental aspects of textile materials and will include investigations of the impact of some environmental parameters on fiber properties, as well as the investigations of a possibility of evaluating textile products on the basis of their ecological safety. Textile products interact with their environment, which influences the changes occurring in them, covered by the term “ageing”. The changes are complex and varied and in most cases quite specific and sophisticated investigations are necessary to understand them. The investigation of fibre ageing under the influence of UV-radiation, ozone and pollutants, is supposed to contribute to understanding the mechanism of the changes on molecular, structural and morphological levels. The other research task deals with the problem of a possible harmful influence of textiles on human health, covered by the expression of “human-environmental safety”. This kind of safety has become one of the basic prerequisites, when speaking about the quality of textile products, and the most important one when trying to sell on the European market. The investigations are supposed to create basic prerequisites for laboratory evaluation of humane-environmental safety. Part of the research task concerns modification of fibre properties using ultrasound waves, as an environmentally very acceptable solution. The effect of ultrasound waves will be investigated on cellulose fibres, polypropylene, polyamide, polyester and wool. The results will be published in scientific research periodicals and conferences, making possible their usage, checking and evaluation. Project aims and objectives In the area of polypropylene and aramide fibres ageing the aim is to complete the investigations started by the previous project, especially concerning the impact of atmospheric pollutants, sunlight, weather conditions and ozone concentration in various stress conditions. The second aim is to investigate possible modifications of fibre properties through the application of ultrasound, and the third aim is to create a scientific and expert basis for testing and objective evaluation of human-environmental safety as a basic prerequisite for textile quality assurance.
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Publications C˘unko, R. and Pezelj, E. (1997), “The ageing of polypropylene through environmental agency”, The 78th World Conference of Textile Institute, Thessaloniki. C˘unko, R., Andrassy, M. and Pezelj, E. (1998), “Elimination of polyester fibre oligomers using ultrasound waves”, Proceedings TEXSc ’98, Liberec. C˘unko, R., Pezelj, E. and Andrassy, M. (1997), Tekstil, Vol. 46, pp. 677-83. Pezelj, E., C˘unko, R. and Andrassy, M. (1997a), “The effect of global climatic change on the fibre ageing”, Proceedings Slovenia Chemical Days. Pezelj, E., C˘ unko, R. and Andrassy, M. (1997b), “The influence of repeated maintenance treatments on properties of PP fibers”, Proceedings The 78th World Conference of Textile Institute, Thessaloniki.
Zagreb, Croatia University of Zagreb, Faculty of Textile Technology, HR-10000 Zagreb, Croatia. Tel: ++385 (0)1 48 43 563; Fax: ++385 (0)1 48 36 058; E-mail:
[email protected] Professor Ivo Soljac˘ i´c, Department of Textile Chemistry and Material Testing Research staff: Professor Drago Katovi´c, Professor Dr Ana Marija Granari´c, Professor Konstantin Moskaliuk, Associate Professor Boris Karaman, Professor -Durd-ica Parac-Osterrman, Associate Professor ´ Ljerka Boki´c, Tanja Pu˘si´c, Nada Hain˘s, Luka Cavara, Sandra Bischoff Vukus˘i´c, Martina Joanelli, Branka Stefanovi´c
Ecologically acceptable finishing process and quality of textiles Other partners: Academic Industrial University of Maribor – Slovenia None Faculty of Mechanical Engineering Institute of Textile Chemistry Source of support: Ministry of Science and Technology of the Republic of Croatia Project started: 22 October 1996 Project ended: 22 October 2000 Finance/support: Kn170,000 per year Keywords: Ecology, Finishing, Textiles The project will be realised in three phases: (1) Construction of a measuring system for computer-synchronised measurements and calculations of clothing production processing parameters, together with measuring parameters varying some technological and technical factors and manners of data processing.
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(2) Construction of a laboratory workplace, ergonomically designed, with the necessary machines and equipment, as well as with a measuring system and multiplane video-systems, measurements and calibration of the system. (3) Measuring processing parameters, correlated with ergonomic, technicological and fashion design factors, with numerical analyses, computer simulations and statistical data processing, structures of technological operations, employing work study methods and MTM systems of ergonomy applied in clothing technology, with some elements of automatisation, processing parameters’ dependence on technological conditions and relevant workplace factors, working methods, conditions of workplace designing, environment, workplace logistics and transport systems in clothing production. Development and patents for new measuring systems should result, together with gaining new and applicable knowledge in the field of clothing technology and clothing engineering. The central hypothesis which the project wants to prove is that new processing parameters should be introduced step-by-step into clothing technology processes, those enabling further scientifically-based quantification of processing parameters. This would result in constructing adequate equipment for precise processing factors’ measurements and their optimisation. Furthermore, interactions among all the processing factors are highlighted and investigated, and the general level of knowledge in the field raised. Project aims and objectives General aim of the project is to approach, through scientific research, current global developments of environment protection in the field of textile technology, in control and attaining “Eco” standards of quality for textile products. The most recent scientific methods of analytical and physico-chemical textile testing are mastered, together with the usage of contemporary finishing agents. The investigation is aimed at contributing to scientific specialization of the researchers involved, especially younger ones, which will result in their personal scientific promotion. It should also introduce Croatian industry and science into global trends of textile construction, production, marketing and control, with the aim of producing ecologically acceptable products of top quality. This will help Croatian industry to approach global markets with economically and otherwise acceptable production. Finishing processes will be tailored so as to reduce pollution as much as possible, and attain the highest possible level of rationalisation. Contemporary analytical methods employed will help textile product control and implementation of the strictest ecological regulations. Academic deliverables Newly-developed crease-resistant finishing process, with low free formaldehyde content. Defining reactive dye coloration changes in crease-
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resistant processes based on formaldehyde-free agents. Investigation of cotton zeta potential changes in mercerisation, as well as the effect of cotton preparation and mercerisation on environmentally friendly processes of finishing and dyeing. The influence of mercerisation on surfactant consumption in obtaining “q” charge on cotton.
Research register
Publications Bischof Vuku˘si´c, S., Katovi´c, D. and Solja˘ci´c, I. (1996), “Influence of cross-linking treatments of dyed cellulose fabric”, Proceedings, 1996 International Conference & Exhibition – Nashville, SAD, American Association of Textile Chemists and Colorists, p. 545. Bischof Vuku˘si´c , S., Solja˘ci´c , I. and Katovi´c , D. (1996), “Durable press finishing combining different derivatives of dihydroxy-ethylene urea”, American Dyestuff Reporter, Vol. 85, pp. 20-27. Boki´c , L. and Stefanovi´c , B. (1996), “Selective determination of chromium (III) and chromium (VI) by ion exchange TLC”, New Achievements in Chromatography Book of Abstracts, Croatian Society of Chemical Engineers, Opatija, Hrvatska. Boki´c , L., Moskaliuk, K. and Cr noja, M. (1996), “Odred-ivanje kroma u bojilima spektrofotometrijskim metodama”, Tekstil, Vol. 45, pp. 421-5. Debelak, F., Jeler, S., Katovi´c, D. and Solja˘ci´c , I. (1997), “Problematika formaldehida v obla˘cilih”, Proceedings, 2nd International Conference Incep 97, Faculty of Mechanical Engineering, Maribor, Slovenia, pp. 331-7. Erla˘c , E., Drag˘c evi c´ , Z. and Vuljani´c , N. (1997), “Organoklorni insekticidi na vuni”, Tekstil, Vol. 46, pp. 255-61. Grancari´c, A.M. (1997), “Tekstilna kemija u prelazu milenija”, Tekstil, Vol. 46, pp. 164-5. Grancari´c, A.M. and Solja´ci´c, I. (1997), “Za˘stita tekstilnih materijala od gorenja”, Rad i sigurnost, Vol. 1, pp. 39-51. Grancari´c, A.M., Pu˘si´c , T. and Solja˘c i´c , I. (1996), “Barium activity number studies of adsorption isotherms of Ba(OH)2 on mercerized cotton yarns”, Proceedings, AATCC International Conference and Exhibition – Book of Papers, American Association of Textile Chemists and Colorists, Nashville, TN, p. 543. Grancari´c , A.M., Pu˘si´c , T. and Solja˘ci´c , I. (1997a), “Adsorpcija Ba(OH)2 na merceriziranom pamu˘cnom koncu Odred-ivanje Ba-broja”, Tekstil, Vol. 46, pp. 429-34. Grancari´c , A.M., Pu˘si´c , T. and Solja˘ci´c , I. (1997b), “Influence of electrokinetic potential on adsorption of cationic surfactants”, Textile Chemist & Colorist, Vol. 29, pp. 33-5. Grancari´c, A.M., Solja˘c i´c , I. and Pu˘si´c , T. (1997a), “Adsorpcija benzopurpurina 4B i natrijevog dodecil sulfata na merceriziranom pamuku”, Proceedings, XV Hrvatski skup kemi˘cara i kemijskih in˘zenjera – Hrvatsko dru˘stvo kemijskih in˘zenjera i tehnologa, Opatija, Hrvatska. Grancari´c, A.M., Solja˘c ic´ , I. and Pu˘sic´ , T. (1997b), “Adsorption isotherms of ionic particles on cotton fibre – the influence of surface charge on adsorption”, Proceedings, AATCC International Conference and Exhibition – Book of Papers, American Association of Textile Chemists and Colorists, Atlanta, GA, p. 527. Karaman, B. and Parac-Osterrman, -D. (1998), “The problem of phthalocyanine dyes”, Proceedings, 3rd International Conference TEXCI ’98, Technical University of Liberec, Liberec, Czechoslovakia, pp. 528-9. Katovi´c , D. and Parac-Osterrman, -D. (1996), “Investigation of free formaldehyde in pigment printing”, Proceedings, 1996 International Conference & Exhibition, American Association of Textile Chemist and Colorists, Nashville, TN, p. 545. Katovi´c, D., Bischof Vuku˘si´c, S. and Solja˘c i´c , I. (1998), “Application of some polycarboxylic acid as durable press finishing agents on viscose fabric”, Textile Science – Texsci ’98, Technical University of Liberec, Liberec, Czechoslovakia, pp. 530-3.
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Katovi´c, D., Bischof Vuku˘si´c, S. and Solja˘c i´c , I. (no date), “Possibilities of wet and humid crosslinking methods for polycarboxylic acid”, Magyar Textiltechnika, Hungarian Society of Textile Technology and Science, Budimpe˘sta, Mad-arska, p. 37. Katovi´c , D., Solja˘ci´c , I. and Kuzmek, B. (1996), “Novi postupak diskontinuiranog bijeljenja pamu˘cnih pletiva”, Tekstil, Vol. 45, pp. 447-51. ˘ unovi´c, T. (1997), “Polikarboksilne kiseline u Katovi´c, D., Bischof Vuku˘si´c, S., Planti´c, L. and C visokom oplemenjivanju pamuka”, Simpozij o novostih v tekstilstvu-, Vol. 31, Naravoslovntehni˘ska fakulteta Ljubljana, Ljubljana, Slovenija, pp. 271-4. Koprivanac, N., Papi´c, S., Hergold-Brundi´c, A., Nagl, A., Parac-Osterrman, -D. and Grabari´c, Z. (1997), “Constitution and dyeing properties of a 2:2 copper complex azomethine dye”, Dyes and Pigments, Vol. 35, pp. 57-68. Mete˘s, A., Parac-Osterrman, -D., Koprivanac, N. and Jovanovi´c-Kolar, J. (1997), “Utjcaj veli˘cine odabranih Mn(II) azometinskih kompleksa na kinetiku bojadisanja”, XV Hrvatski skup kemi˘cara i kemijskih in˘zenjera, Hrvatska, Opatija, p. 198. Moskaliuk, K. and Katovi´c , D. (1997), “Utjecaj upotrebe natrijevog hipoklorita za bijeljenje tekstilnog materijala na zaga-d-ivanje otpadnih voda”, Tekstil, Vol. 46, pp. 139-44. Parac-Osterrman, -D. and Karaman, B. (1997a), “Da li otpadne vode daju ve´c a one˘c i˘sc´ enja obezbojenjem?” , Slovenski kemijski dnevi 1997, FFKT-Maribor, Maribor, Slovenija, p. 333. Parac-Osterrman, -D. and Karaman, B. (1997b), Proceedings, The 78th World Conference of The Textile Institute in Association with the 5th Textile Symposium of the SEVE and SEPVE, Thessaloniki, Gr˘cka, The Textile Institute, Manchester, p. 383. Parac-Osterrman, -D. and Ljerka, D. (1996), “Utjecaj fino´ce sita u tekstilnom tisku – ekolo˘ski aspekt, Proceedings, 14th International Scientific-technical Symposium Intergrafika ’96, ACTA Graphica Zagreb, Hrvatska, Zagreb, p. 169. Parac-Osterrman, -D., Karaman, B. and Horvat, A. (1997), “Dali obezbojenjem otpadnih voda nastaje dodatni ekolo˘ski problem?”, Proceedings, XV Hrvatski skup kemi˘cara i kemijskih in˘zenjera, Hrvatsko dru˘stvo kemijskih in˘z enjera i tehnologa, Zagreb, Hrvatska, Zagreb, p. 336. Parac-Osterrman, -D., Karaman, B. and Joanelli, M. (1997), “Possibility of transfer printing silk with basic dyes”, Proceedings, 78th World Conference of the Textile Institute, The Textile Institute, Thessaloniki, Gr˘cka, pp. 385-94. Parac-Osterrman, -D., Koprivanac, N. and Solja˘c i c´ , I. (1997), “Minimalno one˘ci˘scenje voda pri bojadisanju s C.I.REACTIV RED 120”, Proceedings, 31st Simpozij o novostih v tekstilstvu, Univerza v Ljubljani Naravoslovnotehni˘ska fakulteta Odelek za, Ljubljana, Slovenija, p. 333. Petrovi´c , M., Ka˘stelan-Macan, M., Andra˘si´c , S. and Boki´c , L. (1997), “Application of colour analyzer in quantitative thin-layer chromatography”, Journal of Chromatography, Vol. 771, pp. 251-7. Racane, L., Karaman, B., Trali´c-Kulenovi´c, V., Karminski-Zamola, G. and Fi˘ser-Jaki´c, L. (1997), “Sinteza i svojstva kvarternih soli bisbenztiazola kao potencijalnih fluorescentnih bojila”, Proceedings, XV Hrvatski skup kemi˘cara i kemijskih in˘zenjera, Hrvatsko dru˘stvo kemijskih in˘zenjera i tehnologa, Hrvatska, Opatija, p. 130. Solja˘c i´c , I. (1997), “Intertekstil- Tekstilni dani Zagreb 1997”, Tekstil, Vol. 46, pp. 160-3. ´ Solja˘ci´c , I. and Cavara, L. (1997), “O’suhom pranju tekstilnog materijala pomo´cu teku´c eg CO2”, Tekstil, Vol. 46, pp. 651-3. Solja˘c i´c , I., Hain˘s, N., Bala˘zinec, R., Katovi´c , D. and Bischof Vuku˘si´c, S. (1997), “Impact of creaseproof finishing on color in reactive dyed viscose fabrics”, American Dyestuff Reporter, Vol. 86, pp. 43-7.
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Zagreb, Croatia University of Zagreb, Faculty of Textile Technology, HR-10000 Zagreb, Croatia Tel: ++385 (1) 37 03 153; Fax: ++385 (1) 37 74 029; E-mail:
[email protected] Edita Vujasinovic, Department of Textile Chemistry and Material Testing
Sorption characteristics of medullated wool fibres Other partners: Academic Industrial None None Project started: 1999 Project ends: 2001 Finance/support: 3,000 DEM/year Source of support: Croatian Ministry of Science and Technology Keywords: Textiles, Wool, Sorption, Medullated wool From 500 to 700 tons of greasy wool are sheared in Croatia every year (annual statistics of Croatia 1990-1995). Because of the widely heterogeneous character of the wool sheared, the number of different breeds of sheep, inadequate shear preparation and extremely high content of medullated fibres (Tekstil, Vol. 41 (1992), 591; Stocarstvo, Vol. 48 (1994), 443), coarse wool of domestic sheep is not used in the textile and garment industry. Under these conditions, the quantities of wool stated cease to be a useful raw material and become an ecological hazard. Some developed European countries are faced with the same problem (Nuova Sel Tess, Vol. 5 (1996), 28), and, as coarse wool, due to high content of medullated fibres, can be a useful absorbing and insulating material (both sound and heat insulating), investigations were started to establish the possibilities of using domestic wool as raw material in the manufacture of technical textiles for a wide range of applications (e.g. in civil engineering, building and construction, agriculture and some other branches of industry). Investigations of the physico-chemical (and especially absorptive) properties of medullated wool fibres will show how they can be used in the manufacture of technical textiles, such as various filters, agro-, geo- and thermo-textiles. In this way, coarse domestic waste wool will be used as an environmentally and economically acceptable product, which is in tune with European and global trends of more a rational managing of natural resources, with the purpose of preserving and protecting the environment. Project aims and objectives The quality of most of the domestic wool does not meet the technological requirements stated by the Croatian wool industry, meaning that it is an
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industrial raw material that cannot be utilised. The aim of the investigation proposed is to explore the possibilities of using coarse domestic wool as a raw material in the manufacture of technical textiles. Fine wool fibres are appropriate, ecologically acceptable and a cheap natural raw material for the textile garment industries. Coarse wool fibres are most often a by-product of sheep breeding, which cannot be properly used. The results of investigating the physio-chemical, and especially absorptive, properties of medullated wool fibres will indicate the feasibility of using such fibres as a proper absorbing material (primarily for liquid and solid waste), in the manufacture of a wide range of technical textiles, such as filters, geo-, agro-textiles, sound and heat insulators, etc. In this way, coarse domestic wool, which has become harmful waste through burning without control and years of depositing, will be used as an environmentally acceptable and economically profitable product. Publications Raffaelli, D., Dosen-Sver, D. and Vujasinovic, E. (1999), Kemija u Industriji, Vol. 48 No. 5, pp. 189-96. Vujasinovic, E. and Andrassy, M. (2000a), Proceedings of the 4th International Conference TEXSCI 2000, Liberec, Czech Republic, 12-14 June, pp. 84-8. Vujasinovic, E. and Andrassy, M. (2000b), Tekstil, Vol. 49 No. 6, pp. 277-86.
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Research index by institution Institution
Index by institution
Page
Clemson Apparel Research, Pendleton, USA
81-89
Dresden University of Technology, Germany
10-13
Ellis Developments Ltd, Nottingham, UK
77-79
Heriot-Watt University, Selkirkshire, Scotland
97-102
Hong Kong Polytechnic University, Kowloon, Hong Kong
21-29
Kaunas University of Technology, Kaunas, Lithuania
15-18
Kyoto Institute of Technology, Japan
49-54
Leeds Metropolitan University, UK
54-56
Louisiana State University, USA
62-64
Manchester Metropolitan University, UK
65-69
Queens University, Belfast, UK
5-7
Riga Technical University, Latvia
89-97
Satra Technology Centre, Kettering, UK
18-20
Technical University of Liberec, Czech Republic
56-61
Universidade do Minho, Portugal
74-76
University of Belgrade, Yugoslavia University of Bradford, UK University of Chemical Technology and Metallurgy, Sofia, Bulgaria
7-9 9-10 102-103
University of Guelph, Ontario, Canada
79-81
University of Karachi, Pakistan
13-15
University of Maribor, Slovenia
70-73
University of Newcastle upon Tyne, UK
76-77
University of Zagreb, Croatia
104-110
Yeungnam University, Korea
29-48
111
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Research index by country
IJCST 13,6
112
Country
Page
Bulgaria
102-103
Canada
79-81
Croatia
104-110
Czech Republic
56-61
Germany
10-13
Hong Kong
21-29
Japan
49-54
Korea
29-48
Latvia
89-97
Lithuania
15-18
Pakistan
13-15
Portugal
74-76
Russia Slovenia
113-114 70-73
UK
5-7, 9-10, 18-20, 54-56, 65-69, 76-79, 97-102
USA
8-9, 62-64, 81-89
Yugoslavia
7-9
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Research index by subject Subject
Page
3D modelling, simulation, 5, 6, 11, 25, 100, visualization Art and design 18, 94 Automation, garments 76 Biaxial deformation 15, 17 Body scanning 25 Buying behaviour of apparel 22 CAD in clothing 11, 50 Comfort in clothing 18, 28, 67 Composite yarns, fabrics, PET 29, 30, 35, yarns, thermoplastics 38, 39, 42, 43, 46, 53 Condensation of fabrics 66 Disk twist for composite yarns 38 Disposable textiles, health care 74 Drawing system 32, 45 Dyeing methods, phase and structural changes 102 Environment, hazards, 79, 80, protective clothing 104, 105 Ergonomic clothing design 67 Fashion changes 22 Garment Drape 5, 11, 100 Handle of fabrics 51, 52, 60 Health-care textiles 12, 74, 98 Ironing of fabrics and garments 72 Kawabata parameters 63 Kinanthropometry and somatotyping 21 Leather nesting, algorithm 54, 56 Lingerie apparel design 24 Market research 92 Mechanics of fabrics 9, 15, 60, 63 Moiré topography 25
Networks, Copernicus, EU projects 56 Non-woven materials 7, 98 Physical, mechanical 6, 7, 11, 15, 32 properties of fabrics 36, 46, 51, 52, 60, 98 Perfusion suit 69 Polymeric plasticizers, effects of 13 Protective clothing 79, 80 PVC coating formulations 13 Radio frequency, carbonizing wool 96 Silk-like yarns and fabrics using acrylic staple yarn 41, 45 Softness of fabric 62 Stitch formation modeling, seam process 70, 89 Streaky phenomena of fabrics 31 Stretch/pressure garments 28 Supply chain, clothing, quality 65, 81, 83, control, lost pay 85, 86, 88 Surgical implants 77 Swimwear, degradation of 19 Technical textiles, wool 48, 109 Textile research centres 9, 34 Tow opening 53 Tuft forming at bale opener 49 Vascular grafts 91 Virtual trading 100 Water resistance, permeable membranes 20 Water vapour transfer 68 Weavability, of polyester fabric 36, 56, 58 Weaving machines, Rapier 36, 58 Woven materials 7, 50 Yarn texturing 31, 41
Index by subject
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Research index by principal investigator
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114
Principal investigator
Page
Kukle, S.
94-96 60-61
Ali, S.I.
13-15
Kus, Z.
Alimaq, D.A.
51-52
Lomov, S.V.
Baltina, I.
96-97
McCartney, J.
Chan, C.K.
21-22
Marques, M.J.A.
74-76
Matsuo, T.
52-53
Chen, Y.
62-63, 63-64
Chen, X.
97-100
Crispin, A.J.
54-55, 55-56
C˘unko, R.
104-105
Ellis, J.G.
77-79
Gers˘ ak, J.
70-71, 72-73
Gutauskas, M.
15-18
Hayes, S.G.
67-68
Hinds, B.K.
5-6
Jarvis, C.
81-83
Kancevicha, V.
91-92
Kawabe, K.
53-54
Kim, S.J.
29-30, 30-31, 31-32 32-33, 34, 35-36, 36-37, 38-39, 39-41, 41-42, 42-43, 43-45, 45-46, 46-47, 47-48
Kirkens, P.
57-58
Klavins, A.
89-90
Krievins, I.
92-94
113-114 6-7
Nakamura, M.
49
Nikolik, M.
7-9
Nosek, S.
58-60
Pargas, R.
88-89
Peck, J.
83-84, 85-86, 86-88
Pishev, D.
102-103
Rödel, H.
10-13
Ruckman, J.E.
65-66, 66, 68, 69
Simmons, A.
19-20
Slater, K.
79-80, 80-81
Solja˘c i´c, I.
105-109
Stylios, G.
9-10, 100-102
Suresh, M.N.
50-51
Taylor, P.M.
76-77
Vujasinovíc, E.
109-110
Wilford, A.
18-19, 20
Yu, W. Zhi-Ming, Z.
24-25, 25-27, 28-29 22-24
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Note from the publisher Emerald, the new name and vision for MCB UP Ltd For 2002 the publisher of the International Journal of Clothing Science and Technology (IJCST) will be changing its trading name from MCB UP Ltd to Emerald. You may wonder why! It’s to reflect the success of our Emerald database – our electronic database which, along with much other material, contains current and archival content of this journal. As a reader you’ll almost certainly know the Emerald name because electronic usage of the material contained in our journals has doubled every year since 1996 and the trend continues. During 2000, more than 5.5 million articles were delivered to users – that’s over 16,000 articles every day. But why are we telling you this? Well, partly to explain why this journal will look different in 2002 and why it will carry a new logo. We will be introducing a new logo and giving all our titles a new cover design for 2002 to reflect the Emerald brand. More importantly however, frequently users of material published in our journals are also potential authors. So, if you are thinking of submitting an article for an Emerald journal in 2002 please be assured that you will have the full reach of the Emerald database on your side to ensure that your work reaches the widest global audience.
Note from the publisher
115
Forthcoming volume In 2002, the International Journal of Clothing Science and Technology will continue to serve the needs of researchers, industrialists and engineers in the clothing industry through the publication of academic and industrial research findings. A stringent review process ensures that only papers of the highest quality are published in IJCST. A forthcoming special issue of the Mount Fuji conference in Japan, commemorating Professor Sueo Kawabata’s seventieth birthday, is planned for issues 3 and 4 (August 2002). And of course, issue 6 will be the International Textile and Clothing Research Register (November 2002). If you are interested in submitting an article to IJCST or if you have any questions or comments regarding this, or any other Emerald title, please contact
[email protected]
International Journal of Clothing Science and Technology, Vol. 13 No. 6, 2001, p. 115 © MCB University Press Ltd
