Failure mechanism of aluminium – carbon fibre reinforced polymer interlocking joints through punching

Single-Step Punch Interlocking (SSPI) is a recently developed joining methodology between aluminium and Carbon Fibre Reinforced Polymer (CFRP) aiming to contribute to multi-material design of structural parts. This hybrid joint technology combines adhesive bonding with mechanical interlocking. Elucidating the failure mechanism of the developed joint is relevant to provide insights for future enhancements in performance, increase its lifespan and prevent premature failure. Therefore, the different subcritical failure events were identified through interrupted Single-Lap Shear (SLS) tests and subsequent non-destructive ultrasonic inspection, and the global failure mechanism was described. Results indicate that the addition of the SSPI joint delayed the onset and propagation of adhesive failure between both substrates, providing residual strength and increasing the ultimate load in a 65 % and the absorbed energy of the joint in a 156 %.