Cohesive zone simulations of crack growth along a rough interface between two elastic-plastic solids

It has been known for many years that crack propagation along interfaces is influenced by interface topography or roughness profile. This has given rise to a small body of literature in which interface toughening with stochastic surface finishes, produced by grinding, rolling, or grit blasting, has been the primary focus. However, there is very little information currently available oil the effect of patterned interfaces that are characterized by a minimal number of geometric parameters. In the present article, roughness-enhanced toughening of a cohesive interface between two identical materials is explored with a pure sinusoidal interface morphology that is characterized by its aspect ratio or ratio Of amplitude to wavelength. Sixteen finite element meshes, each with a different aspect ratio, were constructed to study initiation and growth of a semi-infinite interface crack due to remote mode-I loading. The cohesive interface wits modeled with a viscosity-modified Xu-Needleman cohesive zone law, and the solids were characterized with continuum elastic and clastic-plastic constitutive models. Predicted relationships between the aspect ratio and the macroscopic toughness point to key differences in the material models. A set of critical parameters which include the aspect ratio, material and cohesive properties is predicted such that catastrophic crack growth is inhibited due to crack blunting. A clear boundary between brittle and ductile fracture behavior is thus identified. The results suggest some guidelines for practical design of failure resistant interfaces through appropriate choice of geometric, material, and cohesive parameters. (C) 2007 Elsevier Ltd. All rights reserved.