Analysis Of Bolt Connection Plate Looseness Under Transverse Load

With the green and lightweight development of modern rail transit vehicles(such as highspeed rail and subway),in order to reduce the overall weight of mechanical vehicles,a group of light metal alloys led by aluminum alloy are added to the construction of vehicles to replace some cast iron components.Due to the differences in materials,bolt loosening occurs at the joints of some parts.If not handled properly,it may affect the normal operation of the vehicle.In this paper,the bolt loosening differences of connection plates with different materials are analyzed.The aluminum alloy connection plate and the cast iron connection plate are taken as the research objects,and the relative sliding and fretting wear of the bolt contact interface are taken as the research basis.The influencing factors of bolt loosening such as transverse load,preload,connection material and bolt performance grade are analyzed.The research method of combining finite element simulation and experiment is adopted to explore the bolt loosening differences between aluminum alloy connection plate and cast iron connection plate,which provides a theoretical basis for designers to select bolt connection plates with different materials.To this end,the following research work has been undertaken:(1)Based on the Yamamoto theory,the stress deformation of the thread was analyzed,and the deformation of the bolt under axial force was studied.The tightening torque and disassembly torque of the nut were calculated,and the reasons for bolt loosening caused by lateral load were briefly analyzed.(2)The overall structure of bolt connection was analyzed by finite element method,and the influencing factors(lateral load,pre-tightening force and connection material)affecting bolt loosening were analyzed.According to the simulation results,the stress nephogram of the overall structure of the bolt is obtained.After data processing,the decline broken line diagram of the bolt preload is obtained.(3)Based on the fretting wear theory,the bolt is analyzed,and the fretting subroutine is written.The fretting wear simulation analysis of the model is carried out by using the subroutine.According to the simulation results,the stress nephogram of the overall structure of the bolt is obtained,and the change line diagram of the bolt preload is obtained after data processing.(4)The loosening test device of bolted connection structure is designed,and the loosening process of bolt is simulated.The influence of transverse load,preload,steel wire sleeve and bolt performance grade on the loosening of bolt structure is analyzed in the experiment.