Phase field model for brittle fracture using threshold strategy

The standard phase field model suffers from premature damage during brittle fracture, causing performance degradation in advance, which affects the final fracture results in a certain extent. In this paper, an energy threshold strategy and a numerical threshold strategy are proposed respectively to solve the problem of premature degradation of property during the fracture of the standard phase field model, so that brittle fracture can be better described. Meanwhile, an energy decomposition model considering all principal strains and principal stresses is proposed to ensure the accuracy of crack propagation and to overcome the influence of compressive energy on damage. The results of some classical examples show that the simulation results of the proposed energy decomposition model are in good agreement with the actual results. The phase field model with threshold strategy reduces the performance degradation during the fracture process and maintains the linear elastic response before fracture, which verifies the effectiveness of the proposed threshold strategy phase field model in simulating brittle fracture.