Determination of the Rheological Parameters of Fabrics in Bending

Abstract

A simple method which utilizes stress-relaxation data to estimate the single-fiber, (linear) viscoelastic contribution to the total width of a fabric bending hysteresis diagram has been outlined. The method involves an auxiliary stress- relaxation experiment on single fibers, yarns, or fabric. From this stress-relaxation curve the span-to-depth ratio r of the single-fiber bending hysteresis curve is calculated. The product of r and the depth of the fabric hysteresis curve gives the span of the fabric hysteresis curve due to single-fiber, viscoelastic effects. The validity of the method has been demonstrated on single fibers of wool and nylon in bending where no frictional effects occur. In two fabrics investigated it has been shown that by ignoring viscoelastic effects, values of the frictional moment obtained from fabric hysteresis curves may be considerably in error.