Performance of butt strap joints for marine applications

The use of adhesive as a structural fastener is progressively taking place in shipbuilding. However, a series of issues needs to be looked at such as ageing and influence of the tolerance in the adhesive application in order to enhance the knowledge of this technology and reinforce its use in this industry. This paper hence presents the work carried out on butt strap adhesive joints bonding metallic adherends. The influence of adhesive thickness under different ageing conditions on the performance of the joints was investigated. Finite element analysis was carried out to model the joint behaviour taking into account geometric non-linear effects to explain the mechanisms leading to failure. Different failure modes were identified, depending on the level of adhesive thickness. The finite element analysis confirms experimental observations that failure initiated at the horizontal adhesive free surface. Accelerated ageing of the joints suggests interfacial degradation at the steel interface at the edges of the joint overlap.