Modified GTN model to predict the ductile damage of notched DP steel

Abstract

A modified Gurson-Tvergaard-Needleman (GTN) approach is presented in this work. The proposed method incorporates new hardening rules, new voids mechanisms and principles, and shear damage modeling. The data from the X-ray computed tomography (CT) is utilized for the first time to optimize void evolution patterns within the GTN model, with shear-induced damage being integrated into ductile failure prediction for the steels with dual phases (DP). Validation was conducted using DP steel samples with notched geometries positioned at the gauge center. In addition to forecasting stress-strain responses, the model predicts void volume fraction (VVF) values that are subsequently compared with experimental findings. A dynamic cavity evolution approach considering loading rate influences and strain path effects was also implemented to improve prediction capability under complex loading conditions. Furthermore, a multi-scale analytical structure connecting microstructural characteristics with macroscopic damage indicators was established.