Shock waves produced by the interaction of dynamic crack with heterogeneities

Recent experiments reveals how dynamic fracture is characterized by the interplay of crack front with microscopic material heterogeneities. Heterogeneous dynamic fracture remains a current challenge both for numerical modeling and experiments because of the associated fine time and length scales. In this work, we rely on a spectral boundary integral formulation of the elastodynamic wave equations. The numerical discretization focuses along the interface bounding two semi-infinite body and allows a very fine description of the fracture process which is modeled following a cohesive approach. This work study the perturbation of dynamic crack front in presence of a tougher inclusion along the rupture plane. We show numerically how shock waves are radiated from cusp emerging after large distortion of the crack front. We detail how these short-lived bursts persist far from the heterogeneity site and impact the overall rupture dynamics. Since any material presents heterogeneities at a certain scale, we further investigate how the heterogeneous interface properties (heterogeneity size, toughness contrast, crack speed) control the transition from quasi-homogeneous to heterogeneous dynamics. We finally measure the size of the fracture process zone and discuss the role of this critical length scale for heterogeneous dynamic fracture.