Relationships between Fabric Formability, Bias Extension and Shear Behaviour of Outerwear Materials

Abstract

This paper investigates the relationships between fabric formability (a fundamental measure of fabric tailorability), bias extension and shear resistance. The experimental investigation has been performed on a range of thirty-one (fifteen pure wool, twelve wooVpolyester blends, one wooVrayon blend and three pure linen) suiting and trousering materials varying in mass per unit area from 125 to 258 g/m2. Low stress mechanical properties measurements of fabric bending, shear and tensile deformations were obtained using the KES (Kawabata Evaluation System) testers. Furthermore, the 45-degree bias extension behaviour of these fabrics was measured using an Instron extensometer. Following Spivak and Treloar's analysis [12], the bias load-extension and recovery curves were analysed to obtain equivalent shear stress/strain hysteresis curves. The two measures of shear rigidity, one obtained from the KES shear hysteresis curves and the other calculated from the bias extension tests, have been compared for the series of 31 fabrics. Relationships between fabric formability (defined as the product of tensile extensibility under low load and the bending rigidity) and its shear resistance are analysed. In addition, the work also covers the investigation on the relationships between fabric shear properties and formability in bias direction.