COMPUTER AIDED TEXTILE DESIGN Dana Křemenáková 1, Brigita Kolčavová Sirková 1, Ladislav Mecir 1, Ashish Garg 1 et al. 1 Technical University of Liberec, Hálkova 6, 461 17 Liberec, Czech Republic Description of the Fabric/Yarn Design Program The Fabric/Yarn Design Program is an interactive program with a Graphical User Interface programmed in Rebol. The starting screen of the program, where the user chooses the appropriate module: It is an interactive program for computer aided textile design. The purpose of the program is to help a fabric designer to optimize the properties of the fabric/yarn. Physical properties that are taken into account by the program: Yarn Production Technology Yarn Hairiness Yarn Diameter Area Porosity Air Permeability Young Modulus of Fibres Mean Fibre Length Friction Coeficients Fibre Density
Strength Fibre Ductility Hygrometric Properties of Fibres Mass Nonuniformity of Yarn Yarn Twist Creasing Resistance Interlacing Angle Thickness Areal Weight Areal Cover Roughness Bending Modulus Shear Modulus Initial Modulus Shortening Elongation Drapeability Sample input screen: Individual inputs of the program Prediction of the fabric properties in the line fibre yarn - fabric is based on the combination of the mathematical modelling as well as experimental research, including the development and application of the new, non-standard measuring methods designed to express fabric structure and structural mechanics. Yarn hairiness prediction is based on a function graphed in Fig. 1. The value of the function
depends on fibre count and on the technology of yarn production. Values of this function correlate well with values obtained by measurements using the Uster Tester 4. Fig. 1 Function of yarn hairiness from the left yarn count: 7.4, 10, 16.5, 20, 38 tex Fig. 2 2D visualization of the yarn with yarn count = 20 tex Visualization of the longitudinal view of the yarn with defined yarn diameter and yarn hairiness is based on the yarn hairiness function see Fig. 2. Prediction of the yarn strength is based on material properties of fibres as well as on the yarn construction and production technology. The Fabric/Yarn Design System can be used for evaluation of properties of a one- and twocomponent single- as well as two-ply yarn; a 2D visualization is shown in Fig. 3. The visualization is based on the yarn count and the twist of the two-ply yarn. For example visualization of a yarn cross-section is based on yarn count and number of the fibres as well as yarn packing density (i.e. ratio of the fibre volume to the yarn volume). Fig. 3 Two-ply yarn visualization with yarn diameter = 0.18 mm and twist from above 500/m, 600/m, 750/m, 900/m Approximation of the binding wave in the weave repeat for fabric construction is based alternatively on Fourier series or on an approximation using hyperbolic segments. Prediction of the air permeability of the woven fabric [4] follows from the definition of the structural interlacing elements. Structural interlacing models including the fabric thickness define final roughness of the woven fabric. In this case fabric thickness depends on relative waviness of the warp and weft in the fabric as well as warp and weft diameter. Input parameters of the yarn and fabric influence the final 2D visualization see Fig. 4-5.
Fig. 4 Influence of the weave on dobby fabric visualization from the left hopsack, twill, satin Fig. 5 Influence of the areal cover of the fabric on dobby fabric visualization from the left 100 %, 80 %, 60 % Outputs of the system for textile design Inputs to the system are individual tables/values of parameters characterizing fibre, yarn and fabric.the software computes mean values of individual properties and their validity intervals. A user can replace the computed values by specific values (for example value from experimental measuring). Outputs of this system are tables with predicted properties as well as comparative graphs for properties evaluation and 2D visualization of individual textiles. Above-mentioned outputs system users can use for final evaluation of the fibre-yarn-fabric properties see Fig. 6-7. FIBERS mass density mean length UHM initial modulus friction coefficient moisture regain YARNS one and two component yarn single diameter porosity twist CV Uster initial modulus hairiness two ply diameter twist initial mod. hairiness Fig. 6 Final predicted properties of the fibreyarn-fabric
YARN TECHNOLOGY ring,compact,novaspin,rotor FABRICS pattern sett (warp/weft) shortening (wa/we) angle of interlacing (wa/we) length of threads (wa/we) thickness areal weight areal cover (wa/we) air permeability roughness strength (wa/we) (wa/we) initial modulus (wa/we) bending modulus (wa/we) shear modulus drapeability (wa/we) creasing resistance (wa/we) This work was supported by the research project LN00B090 of Czech Ministry of Education. References: [1] Křemenáková, D., and et al.: Internal standard. Research centre Textile 2003. Textile Faculty Technical University of Liberec, [2] Neckář, B., Voborová, J.: A new Approach for Determination of Yarn hairiness. 3rd Autex conf., Necessary Condition for Development of Civilization, June2003, Gdansk, Poland, [3] Sirková, B.: Mathematical model for description of the thread s interlacing in the fabrics using Fourier series, Thesis, Textile Faculty Technical University of Liberec 2002, [4] Havrdová, M., Drašarová, J.: Prediction of woven fabric permeability based on geometrical model of porosity. 6th conf. of Faculty of Engineering and Marketing of Textiles. Lodz. March 2003.