Multiscale sensitivity analysis of failure in composite materials using an interface-enriched generalized FEM

A computational framework is developed to model the failure of composite materials with complex interphase boundaries. The problem of interest in the present study pertains to the transverse failure of fiber-reinforced composites with an emphasis on capturing the debonding of the fiber-matrix interfaces using a cohesive zone model (CZM). The Interface-Enriched Generalized Finite Element Method (IGFEM) is used to model efficiently the geometrical features of the microstructure obtained from reconstructed images of actual composite samples using meshes that do not conform to the microstructure. For cases where fibers are closely packed, a two-interface element is presented, which allows a single finite element to contain multiple cohesive surfaces. We introduce a nonlinear material sensitivity formulation to quantify how variations in the interfacial cohesive zone properties affect the evolution of the transverse stressstrain response.