A continuum damage mechanics model for unidirectional composites undergoing interfacial debonding

A continuum damage mechanics (CDM) model is developed in this paper for fiber reinforced composites with interfacial debonding. The model is constructed from rigorous micromechanical analysis of the Representative Volume Element (RVE) using the Voronoi cell FEM (VCFEM) that is followed by homogenizing microscopic variables using asymptotic homogenization. The microstructural damage mode considered in this paper is fiber-matrix interfacial debonding that is simulated using cohesive zone models in VCFEM. Following a systematic consideration of various order damage tensors, an anisotropic CDM model using fourth order damage tensor with stiffness characterized as an internal variable, is found to perform most accurately for this class of materials. The comparison of this CDM results with those obtained by homogenization of micromechanical analysis show excellent agreement between the two. Hence the CDM model is deemed suitable for implementing in macroscopic finite element codes to represent damage evolution in composites with significant efficiency.