Experimental study on influence of different tightening positions on bolt preload

Abstract

 Aiming at the typical bolted flange connection structure in aero-engine, based on the principle of acoustic elasticity, the supersonic method is used to measure the bolt f preload, and the influence of different tightening positions on the bolt preload and stability is studied. The tightening positions are divided into bolt head and nut, and each tightening position is set with several tightening torques and different lubrication conditions. The test results show that in the full torque range of the bolt without lubrication, the torque coefficient is smaller when the bolt head is tightened, and the distribution of preload under each torque is more uniform and the standard deviation is smaller. Lubricating bolts and nuts, the torque coefficient is also smaller when tightening the bolt head, but under each torque, the preload distribution is more uniform when tightening the nut, and the standard deviation is smaller.