Analysis of bending properties of worsted wool yarns and fabrics based on quasi-three-point bending

Abstract

The bending behavior of worsted wool yarns and fabrics plays a crucial role in handling and performance of end-use textiles. Hence, the fabric/yarn bending properties were studied based on a quasi-three-point bending model by means of the theoretical modeling and the corresponding measuring method. By means of the formula and the measured curves, the curve of bending rigidity and the curvature of a fabric or a yarn can be calculated so as to characterize the bending behavior more precisely than in the previous work. All the experiments on the fabric/yarn bending rigidity have been conducted for both the worsted wool fabrics and the corresponding yarns procured from the fabrics, with the same apparatus bending evaluation system of fabric and yarn, which was developed independently. The measured results of bending rigidity and curvature curve show good correlation with the bending moment and the curvature relationship of the theoretical modeling, and the comparisons of bending rigidity among KES-FB2 (Kawabata Evaluation System for Fabrics-2 pure bending tester), FAST-2 (Fabric Assurance by Simple Testing-2 bending meter), and the independently developed apparatus show that the three systems exhibist reasonably high correlations. It is confirmed that the new apparatus and the theoretical model are both viable and precious. Meanwhile, the theoretical relationship between the yarns and the fabrics has also been discussed, and the theoretical analysis of the bending behavior between the yarns and the fabrics is helpful in selecting a better theoretical model of the fabric-to-yarn bending rigidity ratio.     

Performance of Error Back Propagation vis-à-vis Radial Basis Function Neural Network: Part II: Reverse Engineering of Woven Fabrics

Abstract

This paper describes the application of an artificial neural network approach to engineer the design of woven wool and wool blended suiting fabric, to be used by the weavers. Two neural network models based on error back propagation and radial basis function algorithms are used for ascertaining fabric constructional parameters such as fibre composition, yarn density, yarn tex, weave, yarn crimp and yarn twist to obtain desired low stress mechanical properties and other properties such as breaking strength and extension, bending rigidity, shear rigidity and tear strength of the suiting fabric. Of the two networks, radial basis function network is again found to be fast to train and easier to design than back propagation network. Evaluation of both the models for each fabric property specification shows good agreement between predicted and generally accepted fabric, yarn structure–property relationships.     

Theoretical and experimental analysis of bending rigidity of plain and twill woven fabrics

The study of bending behavior of woven fabrics is an important issue in textile scientific researches and its industrial applications. Different behavior of fabrics such as drape, comfort, and handling can be understood by this study. Bending rigidity of fabric depends on several factors such as weave geometry, bending rigidity of yarn, and yarn density. In this study, estimation of bending rigidity of woven fabric with different twill and plain structures, have been carried out using energy method. Generally, the woven fabric structure is divided into three different section lengths i.e. rigid, semi-rigid, and flexible sections. Thereafter, bi-component and tri-component models for predicting bending behavior of plain and twill woven fabric have been presented. Then, bending properties of fabric based on Shirley apparatus as well as weight per area as a physical property were measured. Good agreement between measured and predicted values, validated our theoretical models for obtaining bending rigidity, except considerable differences observed between experimental and predicted values using bi-component model of plain fabric. Therefore, using assumptions in calculation of the ratio of rigid section length to flexible section length (R₁), the modified model of plain fabric has been proposed.     

空气变形纱的抗弯性能

针对空气变形纱线抗弯刚度过高的现象,以及由此产生的其在日用纺织品和服装领域的应用和发展限制问题,利用悬臂梁法测量经典纱线、空气变形纱及异收缩丝空气变形纱的抗弯刚度值.结果显示,空气变形纱比同规格棉、毛纤维环锭纱的抗弯刚度高出2倍以上.空气变形纱加工成形过程中通过纤维空间排列秩序性变化形成的缠结结构是其抗弯性能的结构根据...     

A Study of Various Mechanisms of Attrition of Fibres as a Result of Abrasion

This paper presents an account of an experimental study of the pure-bending and recovery properties of both continuous-filament and spun yarns. The bending behaviour of yarns is approximately represented by a simple two-element rheological model of an elastic element and a single frictional element acting in parallel. The use of this model allows the bending deformation to be separated into an elastic and a frictional component, measured by the flexural rigidity and the frictional (or coercive) bending moment, respectively. An expression for the frictional couple in yarn-bending is derived from consideration of the lateral forces acting within the yarn and the degree of set of fibres in a twisted yarn. Bending experiments were made with nylon model plied yarns, conventional multifilament yarns, and staple-fibre yarns; it is shown that the level of residual fibre tension within both unset and set yarns can be estimated from the experimental values of the frictional bending moment by semi-empirical means. The mechanisms of bending for conventional polyester-fibre multifilament and worsted-spun yarns are investigated and the effects of yarn linear density, twist, and yarn-setting treatment studied. The bending behaviour of a series of wool-nylon blended-fibre yarns is also discussed in terms of the simple two-element rheological model of yarn-bending behaviour. It is shown that both the flexural rigidity and the frictional bending moment for the blended-fibre yarns can be calculated by assuming independent behaviour of the fibre during bending.     

Application of Wavelet Transform in Characterization of Fabric Texture

Abstract

The authors have developed an image processing system and a wavelet transform (Symlet Wavelet) based processing technique to find the repeat texture of fabric without any priori information. The method is also capable of characterizing the texture of fabric not having an obvious repeat pattern. The proposed methodology is able to measure the warp and weft diameter, and spacing per unit length per yarn and percentage of their coefficient of variation (CV%).     

常用高性能纱线弯曲刚度的测量和表征

由于轴向织物增强薄壳体复合材料越来越成为研究的热点课题。衬纱是轴向织物的重要组成部分,弯曲变形是织物变形的主要形式,因此,衬纱的弯曲刚度对织物的三维成型性能有着重要影响。本文借助KES织物风格仪,通过测量最大弯矩值M_max和拟合斜率值s,表征四种常用高性能纱线的弯曲刚度。实验结果表明：在相同线密度下,高性能纱线的弯曲刚度大于传统纱线的弯曲刚度,四种高性能纱线的弯曲刚度由大到小依次是碳纱线、玻璃纱线、高强聚乙烯纱线、芳纶纱线;高性能纱线的弯曲刚度受纱线中单丝的排列、聚集状态影响,并且随着进入角度的增加而减小。     

大豆蛋白纤维混纺纱的抗弯刚度模型及研究

为了探讨纱线的抗弯刚度对织物的手感和外观的影响,采用混和作用原理建立了混纺纱抗弯刚度的力学模型,并引入纤维在纱线中的转移指数,采用改进的电子式强力仪利用三点弯曲法对大豆蛋白纤维涤纶混纺纱的抗弯刚度进行了测试.结果表明:该模型与实测结果具有很好的一致性,该模型适合于混纺纱抗弯刚度的研究.     

纱线和织物的弯曲刚度

归纳了纱线和织物弯曲刚度已有的测量方法特征及意义，并简要地阐述了改进单纤维电子强力仪测纱线弯曲性能的方法和实验结果，。同时对影响纱线和织物弯曲刚度的因素分别进行了详细的讨论，提出了解决纱线弯曲性能与织物弯曲性能对应测量方法和建立其间理论关系的重要性。     

The method of determination of yarn bending rigidity and friction factor during interaction of fibers

This paper addresses a method of textile yarn bending rigidity determination and gives substantiation thereof. This method is characterized by the closest conformity of the yarn actual bending pattern in fabric. This is achieved by placing the yarn under load between two supports in the form of two taught fibers. The yarn curvature is not determined experimentally but computed thus reducing any computation errors. The tensile load is determined by the deflection angle of the support with the yarn. The supports with the yarn are printed on a 3D printer to reach the maximum accuracy in the determination of their masses’ center. The computation accuracy of the yarn rigidity during bending is also achieved by filling the yarn curve space with epoxy resin and a subsequent analysis of the deflection with the microscope. This results in the creation of a mathematical model that contains the bending moment, yarn curvature and tensile load. The findings of the determination method of the yarn bending rigidity are used to establish the factor of friction of the tested fibers against each other. The dependence of the friction factor on the yarn curve point coordinates will be determined for a certain type of carbon fiber.     

4—THE FINITE-DEFORMATION THEORY OF PLAIN-WEAVE FABRICS. PART II: THE UNIAXIAL-DEFORMATION THEORY

The uniaxial tensile deformation of a fabric is analysed as a special case of the biaxial theory presented in Part I, and the bending rigidity of the yarn at right angles to the tensile direction is introduced.

The structural model presented in Part I is used again to solve the uniaxial case. The biaxial-deformation theory introduced in Part I can, however, be applied directly to solve the uniaxial case because no tension is applied to the yam in the transverse direction, that is, there is no resistance force preventing the straightening of the yarn in the transverse direction. There must, though, be some kind of force, and this resistance force. F ^c, is introduced in this paper and represented by two constants C ⁰ and C ¹. Theoretical considerations for introducing these constants are presented whereby the bending rigidity and the coefficient of friction of the fibre are used. An experimental method for obtaining the constants is also introduced, and the F ^c functions obtained by theoretical and experimental methods are compared.

Finally, the uniaxial load-extension curves of some fabrics are measured and compared with the theoretically calculated curves.     

Elastic Recovery and Performance of Denim Fabric Prepared by Cotton/Lycra Core Spun Yarns

ABSTRACT

Elastic performance coefficient (EPC) and recovery behavior of denim fabrics prepared with cotton/lycra core spun stretch yarns have been presented in this article. The denim fabrics are woven as broken twill weaves in an air-jet weaving machine by the insertion of core spun yarns (lycra filament in core, cotton fiber on sheath) as weft and using 100% cotton yarns as warp. The effect of linear density and stretch percentage of the core spun weft yarns on tensile and recovery behavior of denim fabric have been investigated by employing full factorial design of experiments. It has been observed that the tensile strength and EPC of fabric increase with decrease in linear density and stretch percentage of the core spun stretch yarn. The immediate elastic recovery and delayed elastic recovery increase with decrease in linear density and stretch percentage of the yarns.     

Simultaneous Optimization of Woven Fabric Properties Using Principal Component Analysis

The yarn structure and fabric interlacing pattern are determining parameters for fabric properties. The current study focusses on the multi-response optimization of certain fabric properties like shrinkage, areal density, thickness, flexural rigidity, and bending modulus using principal component analysis for optimum properties. Yarn twist (four different levels), fabric weave design (plain and twill), and yarn type (carded and combed) were the variables of the study. The Taguchi approach of the orthogonal array was sued for designing the experiments, and eight different samples were produced. The yarn twist and fabric weave design were found to have significant effect on these properties of the fabric. Furthermore, using analysis of the variance method, contribution% of parameters to these properties was determined.     

Studies on cotton-acrylic bulked yarns produced from different spinning technologies. Part II: fabric characteristics

The present work is concerned with the study of the characteristics of plain woven fabric produced with cotton-acrylic high-bulk yarns from different spinning technologies. The effects of different factors, namely spinning technologies (ring, rotor and DREF-II, i.e. Group A fabrics), position of shrinkable acrylic feed sliver in DREF-II friction spinning system (Group B fabrics) and proportion of shrinkable acrylic core fibre in core-sheath type DREF-III friction spun yarns (Group C fabrics) on various properties of cotton-acrylic blended bulked yarn fabrics have been reported. The influence of these three variables on the mechanical, handle and comfort properties of fabrics have been studied. The properties of fabrics made of bulked yarns from different spinning technologies are found to be different from the normal 100% cotton yarn fabrics in all respect. Even though the bulked yarns were used only in weft direction, the fabrics with modified yarn structures show appreciable improvement in thermal resistance, moisture vapour transmission, wicking and air permeability. The bending rigidity of the fabrics in weft direction also reduced with improvement in crease recovery in weft direction.     

Exploring the relationship between bending property and crease recovery of woven fabrics

Fabric bending property dictates fabric crease behaviors. Exploring the relationship between fabric bending and crease recovery properties is important for better understanding of fabric performance. This paper presents the viscoelasticity modeling of a creased fabric to characterize the torque and bending deformation by crease recovery and bending parameters, respectively. In the experiment, nine types of fabrics were selected to analyze the relation between bending property and crease recovery property. The bending rigidity (B) and the bending hysteresis moment (2HB) were measured by the KES-FB2 Pure Bending Tester. The initial angular velocity (IV) was measured by a dynamic crease recovery tester. The experimental results showed that B and 2HB generally decrease at the beginning and then almost remain unchanged with the increase in IV. We used an exponential function to express the non-linear relation between bending rigidity and the initial angular velocity, and proved that the initial angular velocity is related to fabric bending property and can be used to characterize the fabric crease recovery property.     

Study of tensile properties of plain-woven fabrics in all-directional using energy method,Part I: theoretical study

Abstract

In the first part of this series, a new mechanical parameter, that is, “Comprehensive Tensile Modulus (CTM)” is introduced and modeled to show the tensile behavior of plain-woven fabrics in the initial linear elastic region of the force-elongation curve subjected to tensile load and extended it simultaneously in all directions. Considering the initial load-extension behavior of fabrics, a mathematical-mechanical model is presented to predict the CTM of fabrics in the initial linear elastic region using Castigliano’s theorem. Based on the generated model, the initial sample length, dimension of the load imposed region, the geometrical shape created in the plain-woven fabric sample during tensile, the structural specification of these fabrics such as yarns sett, yarns crimp in fabric and mechanical properties of yarns such as bending rigidity in both warp and weft yarns affect in the comprehensive tensile modulus of fabric. In order to verify the conformity and accuracy of the model, a preliminary test was conducted on the prepared samples based on a novel tensile test method developed to measure load-extension curve of the fabric samples under the proposed loading condition. A reasonable agreement was found between theoretical and experimental results.     

纱线弯曲刚度测量

分析了测试纱线弯曲刚度各种方法的优缺点 ,着重提出采用改进电子单纤维强力仪法 ,测量毛涤混纺纱的最大弯曲强力等参数 ,来求得弯曲刚度。同时探讨了纱线弯曲刚度与纱线混纺比、捻幅与细度的相关性     

40—AN ENERGY ANALYSIS OF WOVEN-FABRIC MECHANICS BY MEANS OF OPTIMAL-CONTROL THEORY PART II: PURE-BENDING PROPERTIES

The energy analysis of woven-fabric mechanics developed in Part I of this series is extended by considering the pure-bending behaviour of the plain-weave structure as a generalization of the tensile deformation. The boundary conditions for the plain-weave fabric in bending are evaluated, and the ratio of fabric bending rigidity per thread to yarn bending rigidity is computed for a range of fabric structures of different values of weave crimp and degree of set by introducing inequality constraints on the curvature or control variable, a concept borrowed from optimal-control theory. The theoretical results for fabric bending rigidity are compared with experimental work reported by previous workers, and the theoretical shape of the yarn axis in a bent fabric is computed for different fabric curvatures. A comparison of the theoretical results computed by means of optimal-control theory for plain-weave, plain-knitted, and 1 × 1 rib-knitted structures is presented in terms of the following parameters expressed as dimensionless units: modular yarn length, inter-yarn forces, strain energy, total energy, initial fabric tensile modulus. Poisson's ratio, and yarn-decrimping modulus. The results show a surprising similarity in fabric properties expressed in terms of dimensionless parameters, and the implications of the work reported in this paper for future experimental studies of fabric mechanical properties are discussed.     

Evaluating the crease recovery performance of woven fabrics considering bending behaviour in various directions

Since the woven fabric is used on the 3D body, it encounters bending deformation and crease in various directions. Due to the prominence of these deformations in the appearance of the garment, the inspection of bending and crease recovery behaviour of fabric in different directions needs to be considered. In this paper, the evaluation of bending rigidity and crease recovery of fabrics is carried out in various directions. Analysis of the results revealed that fabric-bending rigidity could be expressed as a sinusoidal function of sample orientation towards warp direction. For all the studied fabrics, from warp axis to bias direction, bending rigidity follows a descending trend, however; crease recovery angle has an ascending tendency. Reverse variations were achieved for both properties from bias direction to weft axis due to the variant warp and weft yarn contributions in each direction. Hence, the lowest bending rigidity was obtained in the bias direction (45°), while the highest crease recovery angle was recorded for the mentioned direction. Moreover, an exponential function is utilized to express the non-linear relation between bending rigidity and the crease recovery in different directions of the fabric. The statistical analysis of the results clarified that the effect of fabric direction and structural parameters on the bending and crease recovery behaviour is significant in the confidence range of 95%.     

Analysis of spinning process using the Taguchi method. Part IV: Effect of spinning process variables on tensile properties of ring,rotor and air-jet yarns

Abstract

The yarn samples prepared for migration study were tested for tensile properties. Furthermore, the effect of drafts of the spinning machines on yarn strength and breaking elongation (%) was studied. The effect of spinning position, doff position and material conditioning during testing on yarn tensile properties were also accounted for. The ring yarn was seen to have the highest tensile properties, whereas air-jet yarns the lowest. The low elastic recovery of viscose fibres is the cause of weakest and least extensible air-jet yarns.