Prevailing Torque and Residual Prevailing Torque of Bolt-Nut Connections Having Slight Pitch Difference

In this study, by applying three-dimensional FEM, the nut screwing process is analyzed to obtain the prevailing torque Tp confirming anti-loosening. Since the nut unscrewing properties after the nut tightening is more important to prevent the nut self-loosening, the nut unscrewing is also analyzed to obtain the residual prevailing torque Tpu newly defined in this process. Both results of Tp and Tpu are in good agreement with the experimental results. With increasing the pitch difference, the residual prevailing torque Tpu increases as well as the prevailing torque Tp