مدل سازي و بررسي عوامل موثر بر خمش نخ پود در پارچه تافته

چكيده انگليسي :

Modeling and Investigation on the Effective Parameters in Bending of Weft Yarn in a Plain Weave Fabric Vahid Zarezade vahid zare007@yahoo com Date of Submission February 19 2012 Department of Textile Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiMohammad Ghane m ghane@cc iut ac irU UAbstract Understanding the bending behavior of textile fabrics is an important topic in scientific textileresearches and industrial applications Under the external force the deformation behavior of fiber bundlesthat form yarns or fabric is a function of mechanical properties geometry and interaction of their componentswhich generally involves tensile bending and torsion deformations So fabric mechanical properties such asflexural and shear stiffness can be investigated to study fabric behavior and properties such as drape andformation capabilities handle buckling and tear strength behavior Fabric bending depends on differentfactors such as geometry of fabric yarn bending stiffness yarn density and yarn deflection in the fabric Analysis of yarn bending behavior is based on the relationship between yarn flexural stiffness and both offiber properties and yarn structural parameters Analysis of fabric and yarn bending was started by theBernoulli Euler law that describes pure bending in beams theories A variety of testing methods exists todefine woven fabrics bending rigidity which can be divided into two groups In the first group specifieddeformation is applied after which loading force moments or energy producing bending deformation ismeasured Meantime the second group is based on specimen s deformation measurement under its ownweight Accordingly several studies have been done with theoretical models to analyze and measure theprotrusion of yarn in fabric The one and two fixed end beam models for bending of yarns in fabrics are themost common and easiest methods for determination of flexural modulus and bending rigidity of yarn andfabric In this study fixed fixed beam model was used to determine the weft yarn bending Value of yarndeflection based on elastic theory for small deformation was then determined The weft yarn considered as abeam supported at each end and fixed by two adjacent warp yarns so that deflected at the middle by a verticalload inserted by warp yarn The amount of normal load and yarn deflection is important affecting thestructure and mechanical properties of fabric In this study we studied the effect of variations of weft yarnsdensity on the weft yarn deflection and normal force produced by warp yarns Linear density of weft andwarp yarns and warp density were set to be constant The yarn cross sections were assumed to be circular andpierce s geometry was used for calculations of fabric parameters The bending rigidity of fabrics in weftdirection was measured using the Shirley stiffness tester Flexural rigidity of fabric in the weft directionincreased with increasing weft density The flexural rigidity of weft yarn in fabric was then calculated usingtheoretical relations The normal force was also calculated by using the pullout test Finally the actual weftyarn deflection was measured from pictures of the cross section of fabric prepared by microscope Theresults of actual deflection were compared and discussed with the theoretical values The results of actualdeflection showed acceptable agreement with the theoretical model of elastic bending theory in the case ofsmall deformation Furthermore the actual weft yarn deflection was closer to the theoretical model in higherdensities of weft yarn Keyword Fixed fixed beam Elastic beam Small deformation Yarn deflection Yarn pulloutforce Normal force

زارع زاده، وحيد

مدل سازي و بررسي عوامل موثر بر خمش نخ پود در پارچه تافته

تيردوسرگيردار , تير الاستيك , تغيير شكل كوچك , خيز نخ , نيروي بيرون كشيدن نخ , نيروي نرمال