Molecular dynamics simulation based cohesive surface representation of mixed mode fracture

Molecular dynamics simulation is used to examine mixed mode loading leading to interfacial delamination between two brittle materials. The propagation of a model crack along the interface is simulated under various combinations of far field tensile (mode I) and shear (mode II) stresses. Local stress and local opening data under the steady-state crack propagation condition is extracted from these molecular dynamics simulations, and then used to determine analytical stress vs. opening relations for mixed mode loading conditions. Our simulation results enable the development of a qualitative picture of the traction–separation behavior and functional forms and parameters for a cohesive surface constitutive model consisting of separate normal and shear traction–separation relations.