Combined plastic waves in a thin-walled tube

A theory of plasticity without a yield surface is applied to obtain the simple wave solution of a thin-walled tube subject to the combined step loading. Four wave speeds are obtained in this analysis; all speeds involve the coupling of the longitudinal and the torsional motions as well as the loading and the unloading behaviors. Several numerical examples of our theoretical analysis and their comparisons with the experimental data and with the existing theory are also presented. The constant state region between slow and fast waves is not apparent in the present analysis. This is in good agreement with the experiment. Moreover, the predicted final state of shear strain is higher than the experimental, but less than Lipkin and Clifton's result.