Numerical study of similar and dissimilar single lap joints under quasi-static and impact conditions

Aiming to achieve the targets of reduction of fuel consumption and emissions, automotive manufacturers are increasingly using lightweight materials in the vehicle structures, namely, carbon fibre composites and aluminium alloys. The construction techniques for vehicle structures using this type of materials differ greatly from the techniques used for the most commonly used steel bodies, with adhesive bonding being extensively used due to its capability to bond dissimilar materials. Nevertheless, the application of adhesive bonding poses several challenges to the automotive industry, as dissimilar bonded joints must be designed to perform well under impact. In this work, numerical models were created and validated against previously determined experimental data in both quasi-static and impact conditions of similar and dissimilar (CFRP and aluminium as substrates) single lap joints bonded using a crash resistant adhesive. Cohesive zone models were used to simulate adhesive failure and composite delamination while damage models were used to simulate plastic deformation and failure of the aluminium alloy, allowing to conclude that it is possible to use dissimilar adhesive joints bonded with a crash resistant adhesive in an automotive structure, not compromising the joints performance.