Test and simulation research on the anti-loosening performance of spring washer connecting bolts

REN Yaning; LI Junkuo; WANG Lihuan; GAO Fan; HU Hao; ZHOU Wanzhi

doi:10.16579/j.issn.1001.9669.2026.04.010

Abstract：[Objective]Aiming at the unclear evolution law of anti-loosening performance of spring washer connecting bolts under transverse vibration and the lack of relevant tightening torque design provisions in current specifications,the influence mechanism of surface treatment methods and tightening torque on the anti-loosening performance of bolts is investigated to provide reference for the anti-loosening design of transmission tower bolt connections.[Methods]Firstly,transverse vibration tests were carried out with surface treatment methods(galvanizing,phosphating)and tightening torque(0.5,1.0,1.5 times the standard torque)as variables to compare the preload attenuation characteristics of bolts with different structures.Secondly,a finite element model of bolted connection was established by Ansys software to simulate the stress state of the spring washer and the stress evolution law of the thread area during vibration.Then,a quantitative evaluation method of anti-loosening performance based on residual preload was proposed to clarify the difference of anti-loosening effect of bolts with different structures.Finally,the validity of the model was verified to ensure the reliability of the research results.[Results]The results show that the preload attenuation of bolts under transverse vibration can be divided into three stages:rapid decline,slow decline and rapid loosening.Under 1.5 times the standard torque,the vibration cycles of the galvanized spring washer bolt reaching the residual preload threshold are 450%higher than those of the galvanized flat washer bolt,showing the optimal anti-loosening effect.The spring washer remains in contact with the connecting plate during vibration,which makes the stress distribution in the thread area more uniform.The proposed quantitative evaluation method shows that the average anti-loosening performance of bolts with spring washers is three times that of bolts with flat washers.