On the influence of overlap length on static capacity and fatigue life of adhesively bonded joints with tubular composite adherends subject to torsional loading

Due to their longevity, ease of instalation and reduced stress concentration, among several other positive attributes, adhesively bonded joints are being widely used in mating fibre-reinforced plastic (FRP) composite adherends in petrochemical industry. The study of bonded joints, as opposed to the conventional mechanically fastened joints, has therefore gained great importance. The work presented in this paper follows a comprehensive series of studies being conducted within our research group in characterising the performance of bonded joints in pipes subjected to torsional loading. The study of bonded joints under static and cyclic torsional loading is extremely scarce in the literature, thus, it has been the motivation for this work. This study examines the influence of bond (overlap) length on the performance of single lap adhesively bonded joint within FRP tubular adherends subject to static and cyclic torsional loading conditions. Both experimental and computational methods are used in the investigation to characterise the behaviour of the joint. Different failure modes are observed as a result of issues related to the overlap length and bond fabrication. The concept of 'effective bond length' is also discussed in detail, with a critical view on its usage in practice.