Increasing the efficiency of composite single-shear lap joints using bonded inserts

A numerical and experimental investigation on the use of bonded metallic inserts to increase the strength and the efficiency of single-shear composite bolted joints is presented. Metallic inserts bonded to a composite laminate are proposed to reduce the stress concentration factors at the hole of the composite laminate. Based on the results of numerical models of single-shear composite bolted joints, a novel type of metallic insert, with tapered ends, is proposed. The experimental results show that using tapered end inserts the onset of damage in the composite is delayed. Furthermore, the maximum load sustained by single-shear joints and the joint efficiency are increased due to the creation of new regions of load transfer.