Curing effects on forming and mechanical performance of clinch-adhesive joints of dissimilar materials between AA5754 Aluminum Alloy and Q235 steel

Abstract

The effects of the curing degree of the adhesive during clinching on the forming process and the mechanical performance of the clinch-adhesive joints made of AA5754 Aluminum Alloy, Q235 steel, and Araldite 2015 epoxy adhesive are investigated. First, a differential scanning calorimeter is employed in the curing experiment on the epoxy adhesive to collect the temperature heating rates in order to implement a curing reaction kinetic model that adopts the cure time as the only parameter. Second, the curing effects on the forming, mechanical performance, and failure mode of the clinch-adhesive joints are evaluated under five different curing degrees of the adhesive, including uncured, half-cured, and completely cured states. Finally, the dynamic failure processes of the hybrid joints under tensile-shear and peeling loads are investigated using a digital image correlation system. The results show that a clinch-adhesive joint, which is manufactured when the adhesive is uncured, achieves the highest level of mechanical performance, the hybrid joints that are produced using adhesives in half-cured states present low performance due to defects in the neck and “S” shape locking; specially, hybrid joints are manufactured when curing degree is 0.57, experience neck fractures and thus have the lowest mechanical performance.