ひずみ速度依存性を示す材料における塑性波伝ぱの解析 ひずみプラトーの存在について

Abstract

The present paper deals with a problem of propagation of longitudinal plastic waves in a semi-infinite bar subjected to a constant impact velocity, according to Malvern's strain-rate dependent theory. Especially, we shall discuss whether or not Malvern's theory can account for the plateau of uniform plastic strain adjacent to the impact end of the bar, which is predicted by Karman's theory neglecting a strain-rate effect and is observed experimentally. Malvern could not explain the strain plateau in his own calculations. This is considered so far to be an only weak point in the strain-rate dependent theory, though it can account for the extensive phenomena of high-rate deformation and plastic wave propagation in a bar.In this study, the following conclusions were obtained.(1) The existence of the strain plateau can be also predicted by Malvern's theory.(2) Its appearance requires a relaxation time which is governed by the strain-rate dependence of material and the impact velocity at the end of a bar.(3) As the strain-rate dependence of material and the impact velocity increase, the relaxation time needed for the appearance of the strain plateau increases.