繰返し引張外力によるねじのゆるみ理論に関する検討

抄録

This study aims to clarify the mechanism for self-loosening of threaded joints under repeated tensile force. Sato et al. proposed a theory considering the trajectory of slippage between mating threads and bearing surfaces. However, the behavior of the torsional moment on the bolt shank calculated by the theory is different from that obtained from the experiments with various frictional conditions especially in unloading process in the dynamic loading cycle. In this report, 3D FE analysis was performed to investigate the trajectory of slippage and the resulting torsional moment on the bolt shank, and to clarify the cause of difference mentioned above. The results from 3D FE analysis suggest the necessity of introducing the static coefficient of friction as well as the dynamic one, and their variations along the direction of slippage.