Self-Loosening Mechanism of Nuts Due to Lateral Motion of Fastened Plate

As self-loosening of nuts is really a problem for bolted joints in practical use, countermeasures for the loosening is highly required. In this situation non-loosening fasteners are one of the resolutions for any fastened machinery as an essential mechanical element. Self-loosening of threaded bolt/nut systems has been researched in number of works and most researches were based on experiment and a few were based on the finite element analysis in these years. Using this new approach, various types of nuts can also be examined. Among these nuts eccentric nuts and slit nuts are especially expected to be the solution, as these nuts are reported to endure NAS vibration tests and were not loosened. In the authors’ previous paper, an eccentric nut and a normal nut were analyzed and compared in the aspect of loosening property. In this paper degree of loosening of various nuts was investigated by experiment and the FEA.