Research On Fastening State Identification Method Of High-speed Railway Coupler Structure

The coupler and draft gear is an important part that connects the locomotive and vehicle or vehicle and vehicle during the train running.It will be under vibration during the train running,and will bear traction and impact forces.At the same time,the fastening state of the bolt connection between the coupler and the vehicle body may change due to this.The loosening of blots may be difficult to be detected at the beginning,but if it goes on for a long time,it will affect the function of the coupler and draft gear,which will could not guarantee the stable connection between the vehicles during driving.Therefore,it is necessary to know the tightening state of the bolt connection of the coupler structure in time before the connection problem occurs to determine whether the bolts have loosened and whether they meet the work requirements.The main purpose of this article is to explore the identification method of the tightening state of the coupler bolt connection structure.The tightening state of the bolt connection directly affects the rigidity of the structure’s joint surface,and the change of the structure’s joint surface rigidity will affect the dynamic characteristics of the structure(natural frequency,mode shape,etc.).Therefore,an identification method : natural frequency of the coupler bolt connection structure → the equivalent stiffness of the joint surface → the structure tightening state is proposed.The specific work content is as follows:(1)Establishment of FE model of joint surface of the coupler bolt structure.Establishing the FE equivalent model of the joint surface of the coupler bolt connection structure according to the tightening mechanism and design parameters of the bolt connection of the coupler structure.Each bolt is equivalent to a group of COMBIN14 elements.(2)Operation modal analysis of coupler bolt connection structure.Tesing the coupler structure on site,and getting the natural frequency of the coupler structure under different tightening states.It provides data support for the FEM analysis.(3)FEM analysis of the coupler bolt connection structure.Using ANSYS APDL language to write the loop solution command flow of the FEM analysis of the coupler structure equivalent model.Obtaining the natural frequency of the joint surface under different equivalent stiffness.Combining the analysis results of FEM analysis and operation modal analysis to get the range of equivalent rigidity and natural frequency in each tightening state.(4)Proposal of fastening state recognition method.Taking the range of the natural frequency and the equivalent stiffness in each tightening state as the domain.Designing and building a fuzzy inference system that takes natural frequency as input and the equivalent stiffness of as output.Using it to identify the equivalent stiffness by natural frequency.Furthermore,using the equivalent stiffness which identified by the natural frequency to characterize the bolt connection state of the coupler structure,and finally identify the fastening state of the bolt connection of the coupler structure.