Fabric bagging - Part II: Objective evaluation and physical mechanism

Part I of this series reports on the psychophysical relationship between th e subjective perception of bagging and the residual bagging height. Subject ive perception is mainly influenced by residual bagging height, accounting for 94% of all variations. In Part II, we investigate the physical mechanis m of fabric bagging by developing an equation to describe the fatigue proce ss as decreasing fabric internal energy. On the basis of the equation, we i dentify three fundamental mechanical parameters (elastic energy U, viscoela stic-frictional energy Q(o), and its decay rate delta) and develop a proced ure for objectively evaluating fabric bagging using the Instron tension mac hine. For practical use, we select two criteria (bagging fatigue F-fatig an d bagging resistance F-resist) to characterize bagging behavior. As the phy sical 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, viscoelas tic-frictional energy Q(o), and its decay rate delta) describing the baggin g fatigue process.