Bending Properties of Warp-Knitted Outerwear Fabrics

Abstract

In this paper an experimental study is reported of the low-stress mechanical properties in pure bending for a wide range of synthetic and wool-synthetic warp-knitted apparel outerwear fabrics, including commercially-finished fabrics, laboratory-produced samples, and "laid-in" warp-knitted constructions. A rheological approach is used to describe various frictional and elastic parameters of the fabric-bending hysteresis curves. Mechanisms have been proposed to account for the features of fabric-bending and recovery curves such as their shape, asymmetry, linearity, and degree of hysteresis for bending in the two principal directions of warp-knitted fabrics. The effect of warp-knit construction on fabric-bending properties is examined for a series of laboratory-produced fabrics and the effects of fabric relaxation studied. The bending deformations for a series of laid-in warp-knitted fabrics are analyzed in terms of fabric construction —viz . the manner in which laying-in threads are introduced in the basic warp-knit construction. Fabric-bending properties, particularly for the direction of bending about an axis parallel to the wales, are shown to depend largely on such structural variables as fabric thickness and weight per-unit-area of fabric. The bending behavior of warp-knitted fabrlcs is compared with corresponding properties of both woven and plain weft-knitted fabrics.