Failure analysis of hybrid bonded-hole hemmed joints for dissimilar materials

Abstract

Enhancing transportation efficiency is critical in a society striving for sustainability. Recently, new joining techniques have been developed to enable the construction of more efficient lightweight vehicles. Following this trend, the current research proposes a novel hybrid joining process via the combination of a newly developed joining process by plastic deformation, called hole hemming, with adhesive bonding. The process is examined for the joining of AZ31 magnesium and AA6082-T4 aluminium sheets considering different bonded overlaps. Then, the innovative hybrid joints are subjected to single-lap shear tests at different temperatures to assess their mechanical performance. The bonded-hole hemmed joints showed a maximum joint strength of approximately 11 kN, which is about 3.8 times greater than the strength of hole hemmed joints (2.9 kN). The rise in temperature reduces the strength of the hybrid joint, resulting in a change from failure in the magnesium substrate to a hybrid failure mode (failure in bonded area and the hole bearing). A wider bonded overlap intensifies the probability of the substrate failure and increases the temperature at which the failure mode changes. The results allow to conclude that the bonded-hole hemmed joints have a large potential to be used in lightweight structures.