Non-linear strain invariant failure approach for fibre reinforced composite materials

Abstract

The strain invariant failure theory (Gosse and Christensen, 2001) is a micromechanics-based failure theory that depends on computation of critical strain invariants for the fibre and matrix phases. In this paper, a novel approach is developed for including the non-linear effects of the matrix through the implementation of the J2 flow theory for the matrix response. The non-linear isotropic hardening is introduced for the analysis of a non-linear matrix in square and hexagonal fibre packaging geometries. The results are presented for a common type of structural composite made from carbon fibres and an epoxy matrix. The proposed approach is used to predict the stress and strain concentration factors in a multi-cell array and shows the necessity of including the non-linear response in the analytical approach in this theory.