A stress-invariant based multi-parameters ductile progressive fracture model

Based on continuum damage mechanics and stress invariants, a novel multi-parameters ductile fracture model is proposed by coupling the synergistic effects of hydrostatic pressure and Lode angle in the developed fracture envelope. To improve accuracy for complex stress states, the material parameters associated with the coupling effects are considered and integrated into the proposed damage criterion. Furthermore, the corresponding calibration strategy is also presented to obtain the necessary material parameters. In order to predict the fracture behavior of ductile materials, parallel analyses are performed with the fracture model incorporated into the commercial finite element platform ABAQUS/Explicit through a user material subroutine VUMAT. The validity of this model is examined by comparing the numerical results with the experimental data of notched round bar and compact tension tests. Comparing with other previous stress-invariant based models, it is demonstrated that the new ductile fracture model can predict favorably well with the experimental data, especially for those tests which correspond to wide ranges of pressure and Lode angle. The model can be adopted to predict fracture patterns and to investigate wide range of elastic-plastic ductile fracture behaviors.