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 ひずみプラトーの実験的検証

Abstract

The present paper deals with plastic wave propagation in a bar subjected to longitudinal impact. It has been shown in authors' previous papers that the existence of a strain plateau adjacent to the impact end of a bar can be predicted by Malvern's strain-rate dependent theory and its appearance requires a certain time which is governed by the strainrate dependence of material and the impact velocity at the impact end. In this paper, the theoretical prediction of the previous papers was verified experimentally. First, the strain distributions in a finite length bar and a semi-infinite bar were predicted and the difference between them was examined. Next, the plastic strain distribution was measured in a cylindrical specimen by subjecting it to a longitudinal compression impact with a stress bar which remains elastic during the test. The duration time of impact was also measured on the stress bar.The results obtained are summarized as follows:(1) The strain plateau in a finite length bar was less uniform and less broad than that in a semi-infinite bar.(2) The experimental results for the lead and copper specimens almost agreed with the theoretical predictions. Consequently, it may be verified that the formation of strain plateau is governed by the factors mentioned above.