ABSTRACT
Excitation amplitude versus macroslip plots and preload versus number of excitation cycles were also used to assess rate of loosening, thread pitch, and thread angle. It was found that once macroslip occurs, the rate of self-loosening increases with the reduction in preload. For some frequencies, inertial forces increased the rate of loosening. In addition, it was found that transverse vibration was more dangerous than axial, fine thread fasteners resisted loosening better than coarse thread fasteners, and fasteners with larger thread angle resisted loosening better. It was also noted that the inertial mechanism of self-loosening with this joint model is triggered by the nonuniform distribution of preload along the thread. This suggests that fasteners with a more even distribution of preload would better resist vibration loosening.
