Reliable prediction of crack initiation and growth is essential for the safe design of brittle polymer structures subjected to quasi-static and dynamic loadings. This paper presents a hybrid AT1 phase-field fracture model implemented in ABAQUS/Explicit via user-defined VUEL and VUMAT subroutines. The model is formulated with explicit time integration and a staggered update of the displacement and damage fields. Cracks are represented by a smooth phase field, which allows complex trajectories to be simulated without remeshing. A key methodological contribution of this work is a hierarchical calibration strategy in which the model parameters are identified from quasi-static compression tests on notched PMMA plates. A three-level calibration strategy is adopted, in which the crack path, the global force–displacement response, and the crack-growth rate are matched successively. The calibrated parameter set is then assessed, without further adjustment, to simulate quasi-static tensile tests on notched PMMA plates containing a central circular hole. The simulations accurately reproduce crack initiation and capture the main features of the observed crack propagation in both geometries, supporting the predictive capability of the calibrated hybrid AT1 model for quasi-static fracture analyses of brittle polymers.
Harsi et al. (Mon,) studied this question.