Design for Scarf Joint by Paying Attention to Stress Singularity for Free-Edge of Dissimilar-Metal Interface.

The scarf joint of dissimilar-metal is useful to increase the bonded area. However, the optimization of scarf angle is required for maintaining the joint strength, because brittle intermetallic compounds are necessarily formed at the interface of dissimilar-metal. The design techniques on joint strength characteristics have not fully been clarified. In this study, stress singularities at the intersection of free surfaces and the interface of various dissimilar-metal were investigated using singular analysis. As a result, it was made clear that the no free-edge stress singularities existed in the range of scarf angles, that were determined by the combination of dissimilar-metal. Especially, it was informed that the no free-edge stress singularities existed at the scarf angle of 57° and 123°singularities in case of the copper and aluminum scarf joint. It was also confirmed using finite element analysis that the reduction of stress concentration could be observed by paying attention to the condition of no free-edge stress.