Analysis of overlaminated double-lap joints

Abstract

Adhesively bonded joints are frequently used in aircraft and aerospace structures. A bonding technique called overlamination, where the parts to be joined are connected by adherends that are laminated directly upon the assembly, is more common in the marine industry, and there is a need to assess the stress distribution in such joints. In the present paper, the interfacial stress distribution in overlaminated double-lap joints is investigated. New analytical models of the shear and transverse (through-thickness) normal stresses are derived. The analytical solutions are validated through comparison with finite element calculations, and the accuracy is shown to be high for the unbalanced steel–composite joints as well as the (nearly) balanced composite–composite joints considered. In the former case, the load transfer between the inner and outer adherends is concentrated to a single joint end, while the transfer is distributed to both ends in the latter balanced case. The analysis of the transverse normal stresses demonstrates that the critical failure mode in overlaminated double-lap joints may be related to excessive peel stresses. However, this problem may be alleviated by, e.g. tapering the end of the outer adherends.