| This thesis is concerned with a systematic study of the mechanism of woven fabric bagging. The bagging behaviour of woven fabric was studied theoretically and experimentally with an aim to establish a sound scientific understanding of the problem and to develop an effective testing procedure for quantitative evaluation and prediction of fabric performance during wear.; To understand the psychophysical. mechanisms of fabric bagging perception, a test procedure of subjective evaluation of fabric bagging behaviour was developed by preparing a series of photographs taken from bagged fabric samples and by conducting a series of psychophysical perceptual tests. Both ranking and rating scales were used as the psychological scales. A linear relationship between subjective perceptions and measured residual bagging height shows that perception of fabric bagging follows Stevens' power law. The residual bagging height contributes up to 94% of total variance in the perception of fabric bagging. The rest of the variation may be attributed to the anisotropic behaviour during fabric bagging process.; It was found that fabric residual bagging deformation can be described by the fatigue process as the fabric internal energy decreases during repeated bagging processes. Three fundamental mechanical parameters (elastic energy U, viscoelastic-frictional energy Q0 and its decay rate delta) were identified. A test procedure for objective evaluation of fabric bagging was developed. For practical use, three criteria (bagging resistance, bagging fatigue and residual bagging height) were selected to characterise fabrics' ability to resist deformation and to recover from the deformation, as well as their residual bagging deformation.; A third model was derived by using membrane theory, to analyse the stress distributions for isotropic fabrics under different boundary conditions, including the cases with different bagging height, and the cases with the friction and without the friction between fabric sample and the steel ball deforming the fabric. The results indicate that the stress distribution is nonuniform and non-continuous along both meridian and hoop directions. Comparing the predicted bagging forces with the measured one, it is found that the method is able to predict the trend of bagging force with some deviations.; In summary, a systematic study has been carried out to investigate the bagging behaviour of woven fabric in terms of the psychophysical relationship between subjective perception and objective stimuli from fabric residual bagging deformation, fabric fatigue behaviour during bagging process and its rheological mechanism, and the stress distribution of bagged fabric. Finally, a mathematical model has been developed to predict fabric bagging behaviour from fundamental fibre properties and yarn-fabric properties and structural parameters, which can become a useful tool for prediction and objective evaluation of fabric performance. (Abstract shortened by UMI.)... |
