On the Dynamic Yield of Metallic Materials under Impact Loading

Abstract

In the present paper the dynamic yield of metallic materials under impact loading was analyzed by using the strain-rate dependent theory of Malvern for plastic wave propagation along a bar. Impact tests were also made on lead and copper specimens.The results obtained are summarized as follows:(1) In the case of step loading, a large increase of dynamic yield stress was predicted at the section near to the impact end of the bar by the rate dependent theory, but the increase was considerably small when the rise time of impact velocity was taken into consideration.(2) The dynamic yield stress near the impact end increased with increasing impact velocity and rising time but with decreasing the constant K in the constitutive equation. The yield delay time depended mainly on the magnitude of K.(3) The phenomena of the increase in dynamic yield stress and the yield delay at the impact end were clearly observed in the impact experiments on lead and copper specimens. If the rising time of impact velocity is taken into consideration the rate dependent theory can account for those phenomena quantitatively.