This chapter discusses and reviews the fundamental science and technology behind fabric structure and mechanics. The chapter introduces the extent of knowledge regarding fabric deformations, such as tensile, bending and shearing, and a new kind of testing method based on image analysis to characterize fabric mechanical behavior. A general review of computer simulation techniques for woven fabrics and garments is also presented.

Structure and Mechanics of Woven Fabrics

In this study, a finite element model to predict shear force versus shear angle for woven fabrics is developed. The model is based on the TexGen geometric modelling schema, developed at the University of Nottingham and orthotropic constitutive models for yarn behaviour, coupled with a unified displacement-difference periodic boundary condition. A major distinction from prior modelling of fabric shear is that the details of picture frame kinematics are included in the model, which allows the mechanisms of fabric shear to be represented more accurately. Meso- and micro-mechanisms of deformation are modelled to determine their contributions to energy dissipation during shear. The model is evaluated using results obtained for a glass fibre plain woven fabric, and the importance of boundary conditions in the analysis of deformation mechanisms is highlighted. The simulation results show that the simple rotation boundary condition is adequate for predicting shear force at large deformations, with most of the energy being dissipated at higher shear angles due to yarn compaction. For small deformations, a detailed kinematic analysis is needed, enabling the yarn shear and rotation deformation mechanisms to be modelled accurately.

https://iopscience.iop.org/article/10.1088/0965-0393/17/1/015008/pdf

Finite element modelling of fabric shear

Purpose – To provide researchers with the details of developments in instruments to measure fabric drape and review the literature related to fabric drape.Design/methodology/approach – In recent years, there has been a renewed interest in investigating the aesthetic behavior of fabrics due to the developments in objective evaluation techniques. To understand drape behavior, it is essential to know how drape is measured quantitatively. This paper reviews research related to drape characteristics of fabrics, two‐dimensional instruments and analysis of drape by measuring stiffness, three‐dimensional instruments developed to measure drape, fabric mechanical properties and their influence on drape measurement, and the latest developments in the field including image analysis, the dynamic drape tester and other related research.Findings – Many instruments for measuring drape have been developed including the earliest that assessed stiffness of fabrics, later versions of drape meters and recent innovative instru...

Evaluation of drape characteristics in fabrics

Image-processing in textiles

In this paper the values of elastic constants of woven fabrics for different angles of extension direction were analyzed. Four types of fabric samples of different raw material composition and the same type of weave were tested under tensile forces in seven directions oriented with 15° increment with respect to the weft direction. Elasticity modulus and Poisson's ratio of woven fabrics were determined experimentally in the laboratory. Based on the experimentally obtained values, theoretically calculated elastic constants for arbitrarily chosen fabric directions were calculated. A good agreement between experimental results and the calculated obtained values of the elastic constants was shown, so the theoretical equations can be used with high accuracy to calculate the elastic constants of the fabric in various directions. Therefore, the measurements need to be implemented when the tensile force acting on the fabric only in the warp, weft and at an angle of 45°.

/pdf/determination-of-the-elastic-constants-of-a-plain-woven-30sbquoqen.pdf

Determination of the Elastic Constants of a Plain Woven Fabrics by Tensile Test in Various Directions

Shear behavior is one of the most important characteristics that contribute to the performance and appearance of woven fabrics. In this paper, a model derived from Kilby's work is first used to predict fabric shear rigidity in different directions. Based on the existing literature, a strong linear relationship is found between shear rigidity (G) and shear hysteresis at two angles (2HG and 2HG5). The model for predicting fabric shear rigidity is then applied to the shear hysteresis of a wide range of woven fabrics by comparing the theoretical data and experimental results and presenting them in the form of polar diagrams. The results show strong linear relationships between shear rigidity and shear hysteresis, not only in the principal directions but also in various bias directions. In all experimental results, distinct maxima are presented in the polar diagrams of fabric shear properties between the warp and weft directions.

Shear Properties of Woven Fabrics in Various Directions

This paper presents a model for predicting fabric drape profiles using polar coordinates. The drape coefficient (DC%), node locations, node numbers, and node shape in the fabric drape profile can be predicted accurately with this model. Polar coordinate fitting is used to determine the constants in the drape profile model, and good agreement is obtained between the theoretical and experimental drape profiles of thirty-five woven fabrics. In addition, constants in the drape profile model may also be obtained by bending and shear hysteresis using regression analysis. Good agreements are found between the calculated DC% and the experimental DC% for the fabrics examined in this study. This means a drape profile may be directly predicted from bending and shear hysteresis. Moreover, better prediction of the fabric drape profile may be obtained from the mean value taken in the warp, weft, and ′45° directions than that in the warp and weft directions.

Modeling a Fabric Drape Profile

Many researchers have studied the bending rigidity of woven fabrics in various directions, but there have been no reports on anisotropy in bending hysteresis. In this work, existing models for predicting the bending rigidity of woven fabrics are applied to bending hysteresis in various directions. A wide range of cotton plain woven fabrics is examined by comparing theoretical data with experimental results. The results show that Cooper's model is the most reliable in predicting polar diagrams of bending hysteresis in cotton plain woven fabrics. The results also indicate that the shape of polar diagrams of bending hysteresis along the weft direction spreads outward with an increase in the ratio V introduced by Cooper.

W. M. Lo

Papers

Shear Properties of Woven Fabrics in Various Directions

Modeling a Fabric Drape Profile

Bending Hysteresis of Plain Woven Fabrics in Various Directions