Investigation of loosening resistance based on Junker loosening test of bolt nut connections with pitch differences

Abstract

In our previous studies, a bolt-nut connection with slight pitch difference was considered towards realizing anti-loosening performance and high fatigue strength through axisymmetric finite element method (FEM) and experiment. Also by applying three-dimensional FEM, the nut tightening/untightening process was analyzed to confirm anti-loosening performance indirectly. In this study, Junker's type loosening experiment based on DIN standard is used to confirm the anti-loosening performance directly. The results suggest that suitable pitch difference may provide good anti-loosening performance. The 3D FEM simulation is in good agreement with the experiment. The anti-loosening of the pitch difference nut is discussed by comparing the loosening of the normal nut.