Effect of Pitch Difference and Root Radius on Anti-Loosening Performance of Bolt Nut Connections

Abstract

Bolt nut connections are widely used in the industry. To ensure the safety of structures, both good anti-loosening performance and high fatigue are needed. In previous studies, it has been proven that by enlarging the root radii of bolt nut connections or introducing a pitch difference between the bolt and the nut, the fatigue life can be improved significantly. Based on this, in this study, the anti-loosening performance of the root enlarged bolt nut connections are studied. The prevailing torque and the loosening process of M16 bolt nut connections are simulated by FEM analysis. It is found that even though the anti-loosening performance of the bolt nut connections decreases, introducing suitable pitch differences improves the anti-loosening performance compared to a common bolt nut connection.