Validation of the Phase-Field Model for Brittle Fracture

The phase-field approach to fracture modelling has gained much attention in the field of computational fracture mechanics in the past decade. The phase-field approach eliminates the need for the numerical tracking of the sharp crack discontinuities by the smooth transition of a scalar damage field whose value differentiates between the broken and intact material states. Its variational based approach has been proven to be thermodynamically consistent and able to solve complex fracture processes. Consequently, many different phase-field fracture models have emerged. In this contribution, a few well-known phase-field models for brittle fracture modelling have been implemented within the staggered algorithm with stopping criterion based on the control of the residual norm, recently developed by the authors. The implementation has been conducted within the commercial finite element software Abaqus and expanded to the three-dimensional settings. The experimental validation of the numerical models is then conducted on the tensile, compact tension (CT) and single edge notched bend (SENB) specimens made of the thermoplastic polymer, polymethylmethacrylate (PMMA). It has been demonstrated that with a suitable choice of the length scale parameter, the developed staggered phase-field fracture models can provide valid prediction of the brittle crack initiation and propagation under quasi-static loading conditions.