Analytical Modeling of Self-Loosening of Bolted Joints Subjected to Transverse Loading

Self-loosening of bolted joints is a common issue in structural connections and machine design. This phenomenon can not only cause the industry a lot of losses due to maintenance but can result in catastrophic incidents leading to environment and health issues. This paper presents a new analytical model with an improved criterion that could be used to predict self-loosening of bolted joints. A complete study involving analytical, numerical, and experimental work has been conducted to give an insight of the mechanism leading to self-loosening of bolted joints and support the developed model. Particular focus is put on the effect of the clamping plate thickness on the self-loosening of the joint. A fully instrumented experimental setup, in conjunction with an M12-1.75 bolt, is deployed to track the bolt tension decrease with the application of an imposed cyclic transverse displacement. In addition to the measurement of the transverse relative displacement between the two clamping parts, the clamping and transverse loads are also recorded. Finally, the relative rotation between the bolt and the nut is measured by means of a rotation sensor directly installed on the nut. The results show that there is a good agreement between the analytical, numerical and experimental results. The new model is compared with finite element method (FEM) and experimentation for different plate thickness configurations.