Phase-field simulation of crack propagation in quasi-brittle materials: COMSOL implementation and parameter sensitivity analysis

Recently, the use of the phase-field method (PFM) to simulate the fracture process of brittle materials has attracted increasing attention. The PFM describes the fracture process through a series of differential equations, thus avoiding tedious crack surface tracking and offering advantages in simulating crack initiation, propagation, and bifurcation. The essence of the PFM is a multifield coupling problem, so it is supposed that the COMSOL Multiphysics commercial finite element software, which is particularly suitable for solving multifield coupling problems, should be more efficient and simpler to implement for the PFM. In this paper, a crack propagation model for quasi-brittle materials based on PFM is implemented in COMSOL Multiphysics by means of the solid mechanics module and secondary development interfaces of the partial differential equation (PDE), domain ordinary differential equation (ODE) and differential algebraic equation (DAE). Combined with the collected tensile and shear numerical simulation data, validation studies are carried out both qualitatively and quantitatively. In addition, considering that the PFM involves many parameters would create a significant amount of work for model calibration.Therefore, multifactor sensitivity analysis based on the orthogonal test method is used to identify the parameter' sensitivity. The results show that the use of the solid mechanics module and interfaces of the PDE and domain ODE and DAE are effective for phase-field modelling, and the proposed method could reasonably characterize the whole fracture process of quasi-brittle materials. The sensitivity analysis results revealed that Young's modulus (E) and critical energy release rate (G (c)) are the main factors affecting the output results of the model.