Dynamic crack propagation in a heterogeneous material strip: A closer look at the broberg problem by continuum and atomistic methods

Dynamic anti-plane shear crack propagation in an elastically stiff layer embedded in a soft matrix is investigated simultaneously by continuum mechanics and large-scale molecular dynamics simulation. The analytical solution predicts that the crack can move supersonically with respect to the soft material surrounding the layer. The stress amplitude ahead of the crack is influenced by the crack speed, layer width and elastic properties of both the layer and the matrix. The crack speed is found to depend on the ratio between the layer width and a characteristic length scale associated with energy transport in the vicinity of the crack. The corresponding atomistic simulation results are in good agreement with the theoretical predictions of continuum mechanics. This is a first quantitative study combining continuum-atomistic methods to confirm the recently proposed length scale for energy flux in dynamic fracture [9].