Abaqus implementation of phase-field model for brittle fracture

A phase-field model for brittle fracture is implemented in the commercial finite element software Abaqus by means of UEL and UMAT subroutines. The phase-field method considerably reduces the implementation complexity for fracture problems as it removes the need for numerical tracking of discontinuities in the displacement field that are characteristic of discrete crack methods. This is accomplished by replacing the sharp discontinuities with a scalar damage phase-field representing the diffuse crack topology wherein the amount of diffusion is controlled by a regularization parameter. The nonlinear coupled system consisting of the linear momentum equation and a diffusion-type equation governing the phase-field evolution is solved simultaneously via a Newton-Raphson approach. The implemented crack propagation model does not require predefined paths for crack growth or user-defined surfaces to simulate crack debonding. Post-processing of simulation results is performed via an additional subroutine implemented in the visualization module.