A micro/macro approach to fracture in composites

Abstract The results of an integrated microscopic/macroscopic finite element analysis of fracture in fiber‐reinforced composites are presented. A macroscopic analysis of a composite double‐cantilever‐beam (DCB) fracture toughness test specimen was carried out using a singular finite element method. The effects of fiber layup angle on strain energy release rate are discussed. Results from this analysis were input as boundary conditions to a microscopic model used to calculate J‐integral values in the crack tip region. Nonhomogeneity in this region causes the elastic strain energy release rate to vary with crack tip location and geometry. Elastic‐plastic calculations showed that significant matrix plasticity occurs near fibers away from the crack tip region. The constitutive equation chosen for the matrix plasticity was shown to have an important effect on the J‐integral value. The results show how the microscopic J‐integral is related to the macroscopic strain energy release rate.