A computational model of interface and phase-field fracture

A computational quasi-static model is proposed to simulate fracture in materials and along material interfaces. In any case, the cracks are modelled within the mechanical damage theory introducing two independent damage variables: one for domain damage, one for interface damage. The interface cracks are supposed to appear in a negligibly thin adhesive layer of an interface between two structural components so that cohesive zone models with generally prescribed stress-strain relationships can be implemented within a variationally based model. Similarly, the fracture in the material also considers an energy state and results in phase-field damage which brings about bulk degradation only in a narrow material strip forming the actual crack. The computational approach for finding an approximation of such a variational formulation includes a time stepping procedure with the solution at each instant being obtained by sequential quadratic programming algorithms implemented together with a finite element code.