Profile design of loaded pins in composite single lap joints: From circular to non-circular

Mechanical joints are the weakest links of composite materials and structures. The aim of this study is to investigate the effect of the pin profiles on the stress concentration and load-carry capacity of the pin-loaded single-lap joints subjected to tensile loading. Non-circular profiles of pins are numerically investigated to pursue a possible stress concentration reduction in both the net-tension and bearing stresses of composite single lap joints. Firstly, by varying the characteristic parameters, various round-corner squares are evaluated in terms of peak stresses. Secondly, the square-like profile is transferred to the racetrack-like one in order to gain optimal bearing stresses. Thirdly, the pin of the racetrack-like profile is investigated compared to the circular one, taking into account the through-thickness distributions of stresses. Lastly, the orthotropic effect and the load-carry capacity of the proposed profile are also discussed.