Strength prediction of bolted joints in CFRP composite laminates using cohesive zone elements

A strength prediction method is developed for bolted joints in CFRP composite laminates using cohesive zone elements (CZEs). Three-dimensional finite element models were developed with one element per laminate layer using the ANSYS software (ANSYS, 2009) [1]. CZEs were embedded into the subcritical (matrix based) damage locations that were determined from the X-ray radiographs as detailed in Atas and Soutis (2013) [2]. CZEs use a strength-based failure criterion to predict the onset of damage and a fracture mechanics based approach to predict its growth. The material properties required to simulate the subcritical damage modes were the interfacial strength, fracture energies and the nonlinear shear stress-strain behaviour of the particular material system used. The strength of the joints was determined through the load-displacement curves of the cross-ply laminates and by a simple maximum stress criterion for the quasi-isotropic specimens. It has been shown that the effect of various joint geometries and laminate lay-ups on the joint strength was accounted for by the method developed.