Anisotropic Gurson–Tvergaard–Needleman model considering the anisotropic void behaviors

Abstract

Anisotropic ductile fracture resulting from different microscopic void behaviors has a significant effect on material formability. To accurately predict the anisotropic ductile fracture, an anisotropic Gurson-Tvergarrd-Needleman (GTN) model considering the anisotropic void behaviors was proposed. The effect of high stress triaxiality on void nucleation was considered and remodeled through an additional stress dependent factor in the modeling formulation. Meanwhile, the anisotropic stress triaxiality was adopted. To describe the difference in damage accumulations along different material orientations, a new formulation related to anisotropic critical damage was proposed. Various uniaxial tensions including round bars and plate-shaped specimens were performed along 30° and 60° with respect to the rolling direction for 2024-T35 aluminum alloy. These experimental results, along with previously-published data, were used to validate the proposed model by comparing numerical predictions and experimental results in terms of the load responses and displacements at fracture (DAFs) along different loading directions. Remarkable improvement can be achieved when the contribution of high stress triaxiality, anisotropic void nucleation and critical damage are considered in the modeling of anisotropic ductile fracture. The proposed modeling formulations provide new ideas for the construction of anisotropic GTN series model.