Self-Locking of Bolt-Nut Joints under Repeated Impacts : Theory and Experiments

抄録

In a bolted joint receiving repeated impacts, the slip between external and internal threads is the cause of loosening of the employed fastener and subsequent failure of the joint. Selection of right locking method is important to minimize the detrimental effects of the slip in a joint. In this paper, firstly, a theoretical formula for self-locking of threaded fastener has been deduced from the theory of self-loosening process. Secondly, an equation for critical preload to cope with a certain repeated impact has been derived from the experimental results. Thirdly, by comparing the equation with the formula, the significance of parameters in equation has been clarified and the expressions of the parameters have been found out. Lastly, on the basis of experimental results, the performance of different locking method have been evaluated, the causes of difference of each performance have been evaluated, the causes of difference of each performance have been clarified, and the coefficients of impulsive friction for the threads have been calculated.