A self-adaptive finite element approach for simulation of mixed-mode delamination using cohesive zone models

Oscillations observed in the load–displacement response of brittle interfaces modeled by cohesive zone elements in a quasi-static finite element framework are artifacts of the discretization. The typical limit points in this oscillatory path can be traced by application of path-following techniques, or avoided altogether by adequately refining the mesh until the standard iterative Newton–Raphson method becomes applicable. Both strategies however lead to an unacceptably high computational cost and a low efficiency, justifying the development of a process driven hierarchical extension of the discretization used in the process zone of a cohesive crack. A self-adaptive enrichment scheme within individual cohesive zone elements driven by the physics governing the problem, is an efficient solution that does not require further mesh refinements. A two-dimensional mixed-mode example in a general framework with an irreversible cohesive zone law shows that an enriched formulation restores the smoothness of the solution in structures that are discretized in a relatively coarse manner.