A numerical analysis of relationship between ductility and nucleation and critical void volume fraction parameters of Gurson– Tvergaard–Needleman model

Gurson–Tvergaard–Needleman model is widely used to describe the three stages of ductile tearing: nucleation,
growth and the coalescence of micro-voids. The aim of this article is to study the relationship between volume fraction of voids and the fracture strain ef. The effects of the volume fraction of nucleation, fN, and the critical volume fraction, fc, were analysed. These parameters play crucial roles in the process of ductile damage. A phenomenological analysis is carried out to study the relationship between the different void volume parameters and the fracture strain ef. A method is proposed for the determination of fN and fc, knowing the experimental fracture strain ef. The experimental parameters are extracted from the load–diametric contraction curve of an axisymmetric notched tensile bar test AN2.