A study of fabric anisotropy

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A study of fabric anisotropy

 

Author: Lo, Wing-man Winnie
Title: A study of fabric anisotropy
Degree: Ph.D.
Year: 2001
Subject: Textile fabrics -- Mechanical properties
Anisotropy
Hong Kong Polytechnic University -- Dissertations
Department: Institute of Textiles and Clothing
Pages: xxii, 261, [38] leaves : ill. (some col.) ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1599566
URI: http://theses.lib.polyu.edu.hk/handle/200/3224
Abstract: This thesis describes the investigation of fabric mechanical properties, such as bending, tensile, shear and drape, of apparel and industrial woven fabrics in various directions. Mathematical models were established to predict the anisotropy of these fabric mechanical properties. Wide ranges of woven fabrics, including apparel and industrial woven fabrics were examined by comparing theoretical results with the experimental data and the results presented in the form of polar diagrams. In their investigations into the characteristics of fabric bending properties, many researchers have studied the anisotropy of bending rigidity, but none of these examined the topic of anisotropy in bending hysteresis. In this research, existing models for predicting the fabric bending rigidity were applied to bending hysteresis in various directions. All existing models for the prediction of apparel fabrics are applied to that of industrial fabrics. The results indicated that Cooper's model was the most reliable in predicting the anisotropy of bending hysteresis in different types of woven fabrics. Anisotropic models for the tensile properties, which were measured using KES-F apparatus, namely Tensile Work (WT), Tensile Elongation (EMT), Tensile Linearity (LT) and Tensile Resilience (RT), were derived. Good agreement was found between all proposed models and experimental results of apparel and industrial woven fabrics. The shapes of polar diagrams of these tensile properties can be governed by their values in the warp, weft and +-45o directions. Shear behaviour of woven fabrics is one of the most important characteristics contributing to the performance and appearance of fabrics. Anisotropy of shear properties of apparel and industrial woven fabrics was determined by a model. According to the existing literature, a strong linear relationship exists between shear rigidity (G) and shear hysteresis at two angles (2HG and 2HG5). The model for the anisotropy of fabric shear rigidity was applied to shear hysteresis. In this research, the anisotropy of fabric shear properties was accurately predicted from the proposed model. In addition, the relationships between the anisotropy of bending and tensile and shear properties were investigated. In this study, fabric drape was investigated in two aspects. (1) The relationship between drape coefficient (DC%) and the average values of bending, tensile and shear properties of apparel woven fabrics in the warp, weft and +-45o directions. A higher coefficient of determination, R2, was found by introducing the third direction +-45o than that of the mean values from the warp and weft directions only. (2) Modelling of fabric drape profile (DP) using polar co-ordinate fitting technique from MATLAB software package was also conducted. The drape coefficient (DC%), drape profile (DP), the locations and the numbers of nodes were calculated and predicted.

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