Analysis of energy release rate for fatigue cracked metal-to-metal double-lap shear joints

This paper presents an analytical model for understanding crack propagation behaviour of adhesively bonded cracked double-lap shear joints subjected to tension–tension fatigue loading. The analytical model can be used to calculate the bending moments at the cross sections of the crack tips and strain-energy release rates at the two crack tips. The accuracy of the analytical model is established by comparing the calculated bending moments and energy release rates with those predicted using the finite element method. Numerical and preliminary experimental testing results show that after cracking initiates in one of the two adhesive layers it will then propagate a set distance before crack initiation and growth in the opposite adhesive layer begins. Subsequent crack growth in either adhesive layer then alternates as a function of time.