The Effect of Thread Pitch and Clearance on Self-loosening of Bolted Joints

Aimed at studying the effect of thread pitch and clearance on self-loosening of bolted joints,this paper builds up a three dimensional FEA model of bolted joints in which thread is taken into consideration, and the simulation of self-loosening of bolted joints under transverse vibration is conducted based on the Newmark algorithm.Then the effect of thread pitch and different clearance on self-loosening of bolted joints is analyzed.The results show that the preload of bolted joints with coarse thread pitch falls faster than the preload of bolted joints with fine thread pitch,and the slippage of bolted joints with coarse pitch is acuter than the slippage of bolted joints with fine pitch,thus the self-loosening of bolted joints with fine thread pitch is more difficult to happen;and the larger clearance of bolted joints,the more rapidly the preload falls and the acuter the slippage is.The self-loosening of bolted joints with larger clearance is easier to happen.