A novel computational model to study complex crack paths in dynamic fracture of heterogeneous materials

Crack branching is triggered when, during crack propagation, the energy release rate results much higher than the crack resistance. This is typical during the stage of unstable crack propagation. Moreover, in a dynamic load framework, it can be also triggered by the presence of an interface. The experiments performed by Parab and Chen [1] show that when a crack impinges on an interface the interaction between crack propagation and interface delamination can trigger the crack branching. In [1], this problem has been experimentally analyzed with different interface thicknesses. In the present work, the occurrence of this phenomenon is predicted extending the novel computational model developed by Paggi and Reinoso [2] to the dynamic regime. This computational model roots its basis on the phase field model for brittle fracture. The key novelty concerns the formulation of an interface element, equipped with a tension cut-off cohesive zone model, coupled with the phase field model. The coupling is based on the hypothesis that the stiffness of the interface is degraded by the damage of the surrounding bulk material. The enhancement of this model to the dynamic framework is validated by benchmark numerical examples. Moreover, a comparison with the experimental results obtained in [1] is shown.