Research in Interactive Design (Vol. 4)

Bolted joints are one of the most common elements in aerostructures. Currently, the preload applied to join the parts together is achieved by applying torque to the bolt head or to the nut. In the case of shear joints, an emerging opportunity to optimise structural joints is to apply the preload more accurately. Up to now, the preload effect is most often neglected due to the large scatter on its value due to torque tightening. The aim of this article is to describe the effect of preload on shear joints, for this reason, a numerical and experimental approach has been adopted to demonstrate its influence. In the experimental approach, iterative tightening was used to reduce the scatter on preload. The benefits of preload on high load transfer double lap shear joints will be discussed. In the numerical section, an approach of predicting fatigue life of shear joints is presented. The effect of preload/friction of coefficient is also studied. Finally, practical aspects like alternative tightening techniques and a focus on an industrial application case are also presented.