Fracture mechanics-based progressive damage modelling of adhesively bonded fibre-reinforced polymer joints

A quasi-static progressive damage model for prediction of the fracture behaviour and strength of adhesively bonded fibre-reinforced polymer joints is introduced in this paper. The model is based on the development of a mixed-mode failure criterion as a function of a master R-curve derived from the experimental results obtained from standard fracture mechanics joints. Consequently, the developed failure criterion is crack-length and mode-mixity dependent, and it takes into account the contribution of the fibre-bridging effect. Energy release rate values for adhesively bonded double-lap joints are obtained by using the virtual crack closure technique method in a finite element model, and the numerically obtained strain energy release rate is compared to the critical strain energy release rate given by the mixed-mode failure criterion. The entire procedure is implemented in a numerical algorithm, which was successfully used for predicting the strength and R-curve response of adhesively bonded double-lap structural joints made of pultruded glass fibre-reinforced polymers and epoxy adhesives.