Curing-Induced Debonding and Its Influence on Strength of Adhesively Bonded Joints of Dissimilar Materials

Abstract

Adhesive bonding is thought to be a suitable method for joining dissimilar materials, such as aluminum to steel in multimaterial car-body manufacturing, but when it is combined with other joining methods, such as spot welding or self-piercing riveting, curing the adhesive at elevated temperature induces problems, such as distortion and adhesive debond. In this study, the effects of debonds were investigated by examining load–displacement curve and dissipated energy in lap-shear and peeling tests of artificially debonded joints. The results showed that the debonds caused by curing are of dog-bone type or stripe failure type, and both of them have little influence on the peel strength, but have strong influence on the shear strength and energy absorption. For the lap-shear specimens, the debonds reduce the bonding area, leading to the reduction in maximum shear force. For the double cantilever beam specimens, the debonds produce little influence on maximum peeling force but obvious variations in the peeling load curve. The energy absorption values are inversely proportional to the debonds due to the reduction in bonding area. The overall results from this research facilitate the understanding of the debonding mechanism caused by curing-induced distortion by revealing two types of debond patterns in dissimilar material bonding joints and their influences on joint performance.