Elastic–plastic void expansion in near-self-similar shapes

Abstract

For void growth in an elastic–plastic strain hardening material the preferred shape of the void is calculated, dependent on the macroscopic stress state. Axisymmetric cell model analyses are carried out with a very small initial void size relative to the cell dimensions. Large deformations of the material around the void are modeled until the void volume is four orders of magnitude larger than the initial volume. An iterative procedure is used until the final void shape and the initial void shape are identical. Even when this convergence has been obtained, the void shape does not stay constant during the growth. Thus, the shapes found give only approximately self-similar growth. The results are compared with self-similar shapes determined previously for nonlinear viscous solids, subject to power law creep. For the time independent elastic–plastic material considered here the effect of the strain hardening level and of the initial yield strain are studied.