Dynamic fracture modeling in ductile materials using phase field approach

Abstract

Understanding dynamic fracture in both brittle and ductile materials has attracted considerable attention from engineers and researchers due to its practical importance. In ductile materials, crack initiation and growth are strongly influenced by plastic deformation and the associated microstructural damage, which gradually reduces the material's resistance to crack propagation. Capturing this evolving fracture resistance remains a key challenge for predictive phase-field models. In this study, a phase-field framework is presented in which the effect of plastic deformation on fracture evolution is introduced through a history-dependent fracture resistance. The critical energy release rate is allowed to degrade as a function of accumulated plastic strain, providing a phenomenological description of plasticity-induced weakening without treating plastic dissipation as a direct crack driving force. The formulation is developed within a small-strain elasto-plastic setting based on classical von Mises plasticity with isotropic hardening and is extended to dynamic fracture by accounting for inertia effects in the phase-field evolution. The model is implemented in a commercial finite element environment and examined through a set of representative quasi-static and dynamic numerical examples. The results illustrate the ability of the framework to capture key trends in ductile crack initiation and propagation, as well as the influence of plastic deformation on fracture behavior. The capabilities and limitations of the proposed approach are discussed in the context of existing phase-field models for ductile fracture.