THE INTEFtACTION AMONG ADIABATIC SHEAR BANDS IN SIMPLE AND DIPOLAR MATERIALS

The effect of average strain-rate on the interaction among shear bands in nonpolar and dipolar thermoviscoplastic materials has been investigated. The uniform temperature and stress fields in a block undergoing simple shearing deformations are perturbed when the body just starts deforming plastically and the governing nonlinear coupled partial differential equations are solved numerically. The temperature perturbations introduced are symmetric about the centerline of the block, and have two bumps of unequai heights on each side of the centerline. For nonpolar materials one band on either side of the centerline eventually emerges, the location of the center of the band and its width depend upon the overall strain-rate. For dipolar materials only one band situated at the center of the block forms irrespective of the applied strain-rate. The initiation of the band is significantly delayed in dipolar materials, especially at the higher overall strain-rate studied.