Fabric-bagging: Stress distribution in isotropic and anisotropic fabrics

The internal stress distribution of bagged fabric is studied theoretically and experimentally to investigate the influence of the stress distributions on fabric-residual-bagging deformation. A model is derived by using membra ne theory to analyse the stress distributions for isotropic fabrics under d ifferent boundary conditions, including consideration of different bagging heights and the friction between the fabric sample and the steel ball defor ming the fabric. The results indicate that a non-uniform distribution of me ridian stress and a non-continuous distribution of hoop stress, along with bagging height, are important factors that may influence residual-bagging d eformation and may cause localised damage of the fabric. To investigate the influence of fabric anisotropy on the bagging behaviour of a fabric, the stress distribution of an anisotropic fabric is studied on the basis of the measurements of tensile moduli in seven directions by usi ng fabric strips and of the fabric strain calculated from the relation betw een the geometrical deformation and bagging height of a fabric. The analysi s shows that a non-uniform stress distribution along the meridian direction and variation of the tensile angle theta may cause the difference in the y arn stresses between the warp and weft directions, resulting in different b agging shapes. Comparing predicted bagging forces with measured forces, it is found that the method is able to predict the trend of bagging force with some deviations.