Research On Stress Relaxation Effect In Bolt Joints And Analysis Of Influencing Factors

With the continuous development of modern information technology,the precision of manufacturing products is constantly improving,and the requirements for the assembly field are also constantly improving.However,the old assembly methods can no longer meet the higher accuracy requirements.The old assembly theory has vacancies in some technical fields or The phenomenon of discomfort,and most of the existing assembly files have not been updated for a long time,these problems have seriously hindered the improvement of assembly accuracy.In all kinds of assembly methods,bolt assembly has been widely used due to its strong advantages.However,the control of the bolt node preload force is still not stable enough.Problems that occur when the preload force is too large or too small occur frequently,and the bolt assembly theory is urgently needed.Deeper research and exploration.At present,there have been some studies on bolt assembly,most of which are shown in thread anti-loosening,assembly process optimization,and elastic interaction of bolt groups.More is in the assembly process.Designers often consider the choice of bolt connection.How to avoid bolt loosening,how to avoid bolt breakage failure,etc.,but do not consider a series of problems that occur after bolt assembly is completed,the study of adding the time factor to the bolt joint lacks more theory,and the stress relaxation effect is one of the studies direction.First,this paper proposes the forming mechanism of the stress relaxation effect of the bolt joint,divides the stress relaxation into two stages,and explains how the stress relaxation occurs step by step through a theoretical model,and puts forward a new view on the stress relaxation effect.Combining the nodal problems,the mathematical calculation formula of stress relaxation effect is proposed,and the influencing factors of stress relaxation are further explained by the mathematical formula.Then establish a simulation analysis model of the single-bolt node,analyze the material properties,geometric parameters of the connected parts,and the effect of the thread pair on the stress relaxation through the simulation model,draw the pre-tension relaxation curve,stress relaxation curve,stress cloud diagram,etc.to analyze the single bolt The theory of stress relaxation effect in the node proposes the residual torque during bolt tightening,proving the existence of residual torque and the effect of stress relaxation on residual torque.Based on the single-bolt simulation analysis model,the multi-bolt simulation analysis is carried out,the multi-bolt flange elastic interaction model is established,and the difference between diagonal tightening and sequential tightening and the changes under the effect of stress relaxation are analyzed.Finally,experimental verification is performed to verify the feasibility of the stress relaxation model and verify the residual torque.This article focuses on the simulation analysis of bolt joints,using parametric analysis and control variable method analysis to study the influence of different factors on the stress relaxation effect of bolt joints.By exploring the stress relaxation effect of bolt joints,it provides new directions for bolt joint design.