Strain-hardening and interaction effects on the growth of voids in ductile fracture

Abstract

The growth and coalescence of voids is a common mechanism of fracture in ductile materials. Analytical work on the problem to date has dealt mainly with isolated voids in perfectly plastic materials, so that strain hardening and interactions between neighboring voids have been neglected. These features of void growth are examined here, but only for a simple geometrical configuration. In particular, the growth of single infinitely long cylindrical voids in bodies of rigid-plastic, strain-hardening material is considered. Bodies with both finite and infinite dimensions normal to the void surface are included in the analysis. The exact relation among the pertinent variables: transverse stress, axial strain, hardening coefficient, void strain and void growth rate is presented. Solution via a bounding technique is given for two general cases. The first case is that of an imposed constant void growth rate and the second case is an imposed constant transverse stress. The results show a decelerating effect of hardening on void growth. Application to the ductile fracture problem of void growth in the neck of a tensile specimen demonstrates the accelerating effect of void growth due to interactions between voids.