The Applicability of Elastic/Viscoplastic Theory in Stress Wave Propagation

A viscoplastic constitutive model developed by Perzyna to describe stress wave propagation in rate-dependent materials is examined. The model is considered in terms of dislocation concepts and its ability to provide results which agree with those obtained from uniaxial stress, uniaxial strain, and biaxial strain experiments. It is proposed that the model may be a combination of a number of possible dislocation mechanisms, the dominant one depending on the strain rate. The theoretical model was found to be compatible with published experimental data in the three configurations for aluminum alloys with widely different rate-dependent characteristics. Some limiting conditions are also discussed.