A model for ductile fracture based on internal necking of spheroidal voids

Abstract A ductile fracture criterion based on internal necking of the intervoid matrix ligament is proposed. The criterion assumes the existence of an array of spheroidal voids subjected to extensional growth according to Gurson–Tvergaard flow function. It takes into account the influence of matrix strain hardening, void shape evolution as well as the softening due to existence of voids. Comparison among the proposed criterion and other criteria existing in the literature indicates its appropriateness for axisymmetric and plane strain conditions for unnotched and notched bars. The predictions of the proposed criterion are shown to be valid for a large variety of alloys for which the fracture strains and the micro-mechanical data were mostly identified experimentally.