A damage model for predicting ductile fracture with considering the dependency on stress triaxiality and Lode angle

This paper aims to present a Continuum Damage Mechanics based fracture model. Two yield surfaces, plastic and damage, are utilized to develop the model. A modified ductile fracture model coupling both stress triaxiality and Lode angle parameter is then proposed. The proposed model is applied to construct the fracture loci of four types of metal alloys: steel HY100, steel PCrNi3MoVA, aluminum 2024-T351, steel TRIP690 and steel A533B. The prediction is also involved investigation of the dependency of damage evolution on stress triaxialities for steel HY100 and steel A533B. The new model is also utilized to construct the Fracture Forming Limit Diagram (FFLD) of steel TRIP690 to validate the performance of the model. The predicted results are in good agreement with the experimental data over a wide range of stress triaxialities. Comparison between the proposed model and some fracture criteria is also provided, and the results indicate that the proposed model has significant potential to predict ductile fracture as well as FFLD at both low and high triaxialities. In order to validate the capability of the model in structural response, the proposed model has been implemented into user-defined subroutines VUMAT in the finite element program ABAQUS/Explicit. For this purpose, the explicit stress integration algorithms of the model have been explained. The model has been validated by comparing the predicted results with experimental data of steel A533B. The results show the excellent correlation between experiments and simulation for the force and damage results as well as the fracture shape.