Influence of surface morphology on the adhesive strength of aluminum/epoxy interfaces

Adhesively bonded aluminum joints have been increasingly used in automotive industry because of their structural and functional advantages. Interfacial debonding in these joints has become a major concern limiting their performance. The present work is focused on experimental investigation of the influence of surface morphology on the interfacial fracture behavior of aluminum/epoxy interface. The specimens used in this experimental study were made of an aluminum/epoxy bimaterial stripe in the form of a layered double cantilever beam (LDCB). The LDCB specimens were debonded by peeling off the epoxy layer from the aluminum substrate using a steel wedge. Interfacial fracture energy was extracted from the debonding length by using a solution for the specimen geometry based on a model of a beam on an elastic foundation. This model was validated by direct finite element analysis. The experimental observations establish a direct correlation between the surface roughness of aluminum substrate and the fracture resistance of the aluminum/epoxy interface. The results emphasize the importance of choosing surface features at an appropriate length scale in studying their effects on interfacial fracture resistance.published or submitted for publicationis peer reviewe