Quasi-static and dynamic performance of novel interlocked hybrid metal-composite joints

This study presents a novel hybrid technique for joining composites to metal, employing an array of macroscale interlocking features on the faying surfaces of adhesively bonded adherends. Single-lap, interlocking adhesive joints (IAJs) and baseline adhesive joints (BAJs), are tested at quasi-static and transient dynamic (0.5 m/s and 3 m/s) loading rates. The joint deformation mechanisms are examined and fractography analysis is performed at the macro and micro scales. Results indicate a 10% increase in lap-shear strength, and 75-120% increase in work to failure for the IAJs compared to the BAJs, at all loading rates. In addition, IAJs exhibit improved damage tolerance compared to adhesive joints, due to reduced joint rotation, more stable adhesive fracture growth, and the ability to sustain load even after cracks have propagated through the adhesive at the ends of the overlap region. The high energy absorption capacity (23-38 J) of IAJs indicates they could be used to significantly improve the crashworthiness performance of multi-material transportation structures.