Radial Stress Release Phenomena in Plate Impact Experiments: Compression-Release

Abstract

A common objective in designing a postmortem type of plate-impact experiment is to be able to attribute the observable residual effects (such as residual strain, hardness, or dislocation density) primarily to the conditions which existed while the material was in a state of uniaxial strain. In the past it has generally been assumed that effects due to radial stress release phenomena, which are always present in such an experiment, are of secondary importance. In order to test the validity of this assumption, a two-dimensional Lagrangian finite-difference computer program is used to model physical experiments representative of common practice. Target plate dimensions, the target and flyer plate material, and the impact velocity are systematically varied for circular target plates with, and without, guard rings. The results show that in many cases the effects of radial release phenomena are too large to ignore. Conclusions are presented which serve as guidelines for designing experiments to minimize radial release effects.