Abstract:

The stress distributions of three types of joints, namely balanced single-lap bonded/ bolted hybrid joint and corresponding bonded only joint and bolted only joint, were investigated and compared by gradually developing accurate three dimensional Finite Element Analysis (FEA) models. First, the FEA model of bonded only joints was built and employed to obtain the adhesive stress of the joint, which was in good agreement with that obtained by theoretical model in the literature. Then, the bonded only joint FEA model was extended to the bonded/bolted hybrid joint model. The adhesive stresses in the hybrid joints with two kinds of adhesives were compared with that in the corresponding bonded only joints. The load sharing ratios by the adhesive layer and by the bolt of the hybrid joints were calculated. Results show that the adhesive stress distribution of the hybrid joints with phenolic resin adhesive was almost the same as that of the corresponding bonded only joints; the bolt shared very little load. However, in the hybrid joints with acrylic resin adhesive, the adhesive stress decreased significantly and the bolt shared large load. Finally the FEA model of the bolted only joint corresponding to the hybrid joint was built. Comparison shows that hole stress concentration in the hybrid joint is much lower than that in the bolted only joint, which means the hybrid joint can effectively eases stress concentration. In hybrid joints with low modulus adhesive, load can be shared by the bolt and the adhesive. So the performance of the hybrid joints is better than that of traditional joints.

Key words: mechanics, bonded/bolted joints, finite element analysis, stress distribution, load transfer ratio