Progressive failure analysis of bolted joints in composite laminates

Abstract

A three-dimensional progressive failure analysis methodology was developed to predict the strength of double lap bolted joints in [0 degrees/90 degrees/+/- 45 degrees](2s) carbon fibre reinforced plastic laminates. An experimental programme was conducted to verify and validate the proposed computational model. Good agreement was obtained between the experimental data and predictive model. A parametric study was conducted for varied clamping torque and friction coefficient values. The well known effect of those variables on the joint strength was captured. Although the in-plane mode of failure of each individual layer around the fastener hole was predicted, X-ray radiographs have shown that delamination failure is particularly dominant around the washer's outer edge. At present, the proposed model does not account for delamination onset and propagation. Future work will involve implementing cohesive zone elements in regions of interest to capture this interlaminar cracking, a work in which the authors are currently engaged in.