Discrimination of fabric mechanical properties and buckling deformations in a novel fabric handle evaluation system

• Main Author: Wang, Yiyi
• Other Authors: Mao, Ningtao ; Russell, Stephen
• Published: University of Leeds 2016
• Subjects: 620.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702614

This research is to study the characteristics of fabric properties measured in an innovative fabric test system, Leeds University Fabric Handle Evaluation System (LUFHES); it is designed for objectively evaluating fabric handle in a simpler, relatively low cost and automatic method. The quantification of fabric handle in the LUFHES is based on the energy consumption of fabric shells during their cyclic shear twisting and cyclic axial compression buckling deformations, as well as the fabric surface properties evaluated from fabric-fabric self-friction process. In this study, low stress fabric mechanical properties measured in the cyclic axial compression buckling, shear twisting and fabric-fabric friction of fabric shells in LUFHES were analysed to establish the new technological approach in relation to fabric handle analysis. In addition, the fabric properties measured in the LUFHES were compared with the fabric properties measured in fabric unidirectional deformation processes such as the Kawabata Evaluation System for Fabric (KES-F) and the Fabric Assurance by Simple Testing (FAST) to disclose the differences of these three fabric measurement systems. Properties of 29 fabrics including 12 woven fabrics, 7 knitted fabrics and 10 nonwoven fabrics were studied in this project in order to understand the mechanical properties of fabrics which are made from different fibres, having different fabric structures, fabric weight and thickness measured by using the LUFHES system. The suitable pre-tension for the LUFHES tests was determined by analysing the effect of pre-tensions on the energy consumption of various fabric deformations in cyclic fabric shell compression buckling-recovery processes, and suitable pre-tension force for fabric measurements in the LUFHES was identified in the range of 1.2N/m and 2N/m. Fabric shear and buckling properties measured in the LUFHES were compared with shear and bending properties obtained in both the KES-F and FAST systems to investigate the differences between these three systems in discriminating fabrics. It was found that fabric shear properties obtained in the FAST were different from those obtained in the LUFHES shear tests for woven fabrics due to insufficient shear deformations in woven fabrics in FAST test. It was also found that shear properties obtained in the KES-F shear tests were not in agreement with those obtained in the LUFHES tests due to greater extension forces applied on fabrics leading to greater fabric elongation before its shear test in the KES-F system for some fabrics such as knitted and nonwoven fabrics. Thus, fabric discriminations in terms of fabric shear properties obtained in these three testing systems will be different. The correlation between critical buckling force and bending properties was found to depend on the fabric types and measurement methods. Critical buckling forces of woven and nonwoven fabrics obtained in the LUFHES were found to correlate well with bending rigidity obtained in the KES-F system, while critical buckling forces of knitted fabrics correlated well with the bending rigidity obtained in the FAST system. It was found that there are several unique advantages using the fabric-fabric self- friction method in objective measurement of fabric handle over other methods such as fabric-metal and fabric-artificial finger frictions. The characteristics of fabric-fabric self-friction in the LUFHES friction test were analysed theoretically and experimentally, as well as compared with that of the KES-F fabric-sensor friction/roughness test. It was found that fabric-fabric friction coefficients obtained in LUFHES were greater and in a wider range than those obtained in the KES-F fabric-sensor friction test, and the spectrum of LUFHES fabric-fabric friction profile has advantages in differentiating the main fabric characteristic structures. In summary, the unique low-stress mechanical properties (shear and buckling) obtained in the LUFHES tests reveal insightful information of mechanical properties of fabric shell during biaxial deformations. The fabric-fabric friction was found to have advantages in discriminating fabric friction coefficient and fabric surface structures. Thus, the LUFHES has the potential to be used to sensitively evaluate fabric handle.