Shear-strain-rate effects in a high-strength aluminum alloy

Methods of investigating the plastic flow of materials at high rates are reviewed, and experiments are described in which thin-walled tubular specimens were subjected to dynamic torsional loading. These experiments were performed using a modified version of a torsional Hopkinsonbar apparatus used in earlier work. The results show that, at strain rates of order 10³ sec⁻¹, the stress-strain curve of the alloy tested does not differ significantly from that found at 10⁻³ sec⁻¹. In tests involving the propagation of a stress increment, however, it was found that the speed of propagation was that of elastic shear waves, indicating that the initial response of the material is essentially rate dependent.