Effects of shape on unstable growth of cavities interacting with surrounding small voids

Abstract

The possibility of unstable cavity growth in a ductile metal containing many voids has been studied recently. The central spherical cavity was discretely represented, whereas the surrounding small-scale voids were represented by a porous ductile material model in terms of a field quantity that specifies the variation of the void volume fraction in the surrounding metal. Here the influence of the initial shape of the central void is analysed by considering various initial spheroidal void shapes. The evolution of the void volume fraction fields around the central void is very sensitive to the void shape. If there is no porosity in the surrounding material, the central void in a high triaxiality stress field develops towards a near spherical shape before unstable growth occurs. However, in the presence of surrounding small-scale voids the evolution of the porosity fields has much influence on the occurrence of the maximum stress point, where the central void will start to grow rapidly in interaction with fracture evolution in the surrounding material.

Keywords:

• plasticity
• instability
• finite strains
• ductile fracture