Bonded structures improvement by the dual adhesive technique

Abstract

A common technique to reduce stress gradients in adhesive joints is to use the dual adhesive technique, which has proven to reduce peak stresses in single-lap joints. However, other joint configurations could benefit from this technique. This work experimentally and numerically evaluates stepped-lap dual-adhesive joints (DAJ) between aluminum adherends, for various overlap lengths (LO), and carries out a detailed comparison with stepped-lap single-adhesive joints (SAJ) with the same individual adhesives (Araldite® AV138 and Araldite® 2015). The joint behavior was predicted by cohesive zone modelling (CZM) with a triangular law. The analysis of the results is presented in the form of failure modes, stress analysis, maximum load (Pm) and energy required to failure (U). It was concluded that, in general, CZM presented precise predictions and are a valuable tool for the design of both SAJ and DAJ. However, no significant increase in strength was achieved with DAJ, although using more ductile adhesive can promote better DAJ results.