Fabric Bagging

Abstract

Part I of this series reports on the psychophysical relationship between the subjective perception of bagging and the residual bagging height. Subjective perception is mainly influenced by residual bagging height, accounting for 94% of all variations. In Part II, we investigate the physical mechanism of fabric bagging by developing an equation to describe the fatigue process as decreasing fabric internal energy. On the basis of the equation, we identify three fundamental mechanical parameters (elastic energy U, vis coelastic-frictional energy Qo, and its decay rate δ) and develop a procedure for objec tively evaluating fabric bagging using the Instron tension machine. For practical use, we select two criteria (bagging fatigue F fatig and bagging resistance Fresist) to characterize bagging behavior. As the physical stimulus to subjective perception of bagging, fabric bagging residual height depends on these mechanical parameters. Further, subjective ratings on bagging are predictable from the two criteria selected (bagging fatigue and resistance) and from the three parameters (elastic energy U, viscoelastic-frictional energy Qo, and its decay rate 8) describing the bagging fatigue process.