Softening by void nucleation and growth in tension and shear

The effect of void nucleation and growth on overall stress-strain behavior is investigated for solids undergoing plastic straining under axisymmetric and shearing conditions. Contact between the void surface and the nucleating particle is taken into account and is found to be important under shear and under axisymmetric straining when the stress triaxiality is low. The notion of the macroscopic stress drop due to nucleation of a void is defined and computed, both for isolated voids and for voids in periodic arrays. The stress drop for an isolated void in an infinite matrix can be used to predict softening due to void nucleation when the void concentration is dilute. Interaction between voids in shear during nucleation is analysed numerically and softening effects are calculated along with large strain aspects of void deformation during subsequent growth.