Simulation on loosening behavior of threaded fastener under transverse vibration

Threaded fastener is widely used in engineering machinery industry. However, loosening is a big problem of threaded fastener, which can affect operation state and working life of equipment, and even cause severe accidents. To solve the problem of thread loosening, the loosening mechanism of threaded fastener under transverse vibration is presented here. In this work, the theory of Timoshenko beam is employed to compute a bending stiffness, and the finite element method is employed to obtain contact stiffness. By using lumped-mass method with these stiffness, a three-degree-of-freedom dynamical model of threaded fastener under transverse vibration is developed to study the effects of amplitude of transverse activation on dynamical response, including preload, nut relative rotation angle, force between bolt and the clamped parts. Based on the simulation results, the loosening behavior of threaded fastener can be well understood and provide theory guidance for design reliable threaded fastener.