Numerical study of impact behaviour of mixed adhesive single lap joints for the automotive industry

The automotive industry is now extensively using multi-material structures to reduce vehicle weight. Joining these dissimilar materials effectively in a single structure demands the use of adhesive bonding, but the presence of stress concentrations leads to low mechanical performance. Mixed adhesive joints have been proposed as a solution for this issue, using two adhesives in the same joint, combining stiffness and flexibility on the same overlap, improving performance. This work focuses on the numerical modelling of the mechanical behaviour of these joints, using previously published experimental data for validation. The proposed models use cohesive laws with strain rate dependent data to simulate quasi-static and impact loads on several configurations of mixed adhesive joints, using four different adhesives. The models were able to predict the behaviour of most configurations under study, especially for the stiffer adhesives. The model was found to be less effective for modelling high ductility adhesives under impact.