Simulation Study On Vehicle Response Characteristic Identification Of Rail Fastener Loose

Rail fastener is an important component of track system.It can fix the rail on the track plate,prevent the rail from moving relative to the track plate and provide some flexibility.Fastener will inevitably occur loose phenomenon by adverse natural conditions and rail vehicle dynamic load in long-term operation and service process.When the fastener is loose,the vibration characteristics of some components of the vehicle will change to a certain extent,which will have a great impact on the stability and safety of high-speed vehicle running.In order to identify the characteristics of the loose state of the rail fastener in the wheelset vibration response signal of the rail vehicle.Based on the theory of finite element and multi-body dynamics,a rigid flexible coupling model of vehicle track is established by combining ANSYS and SIMPACK.It solves the problem that the traditional rigid rigid vehicle track model established by SIMPACK can not set the fastener loose state.First,the model of the rigid body vehicle and the excitation model on the running line of the vehicle are established in SIMPACK.Secondly,the discrete model of rail and rail plate is established by using ANSYS,and the modal analysis of substructure is carried out to generate the result files for the application of SIMPACK.Finally,the SIMPACK can only realize Hertz contact between two rigid body defects,establishment of a mass and moment of inertia and interference effect of virtual rail in rail between the rigid and flexible wheel rail,and according to the force equilibrium and deformation coordination condition to realize data exchange,so as to realize the coupling between the rigid flexible wheel and rail.To establish the simulation model of vehicle track coupling.Using the vehicle track coupled model,the simulation method by modifying the fastener in SIMPACK force element parameters to simulate different degree of fastener loosening,A total of 5 loosening lever were simulated,not loosening,loosening 25%,loosening 50%,loosening75% and loosening 100%.Combined with three kinds of typical fastener loosening conditions,vertical vibration acceleration signal of the wheel pair and the the body are simulated at the speed of 200km/h.According to the simulation results,the final analysis of the vertical acceleration of the wheelset is selected.In order to identify the loosening of the fastener from vertical vibration signal characteristics of wheel,Hilbert Huang transform is applied to the analysis of vibration signal of wheelset.In view of the lack of intrinsic mode function orthogonality of Hilbert Huang transform first step empirical mode decomposition of the shortcomings,using the method of orthogonal empirical mode decomposition of each intrinsic mode function orthogonal treatment,can be strictly orthogonal between each intrinsic mode function,to prevent the leakage of energy.Based on this,the principle of relevance is applied to eliminate the inherent pattern components of poor correlation with the original signal.The Hilbert spectrum cannot directly reflect the different degree of loosening of the fastener,the quantized and the information entropy theory into Hilbert spectrum processing,different degrees of fastener vertical wheel loose three typical working conditions of the comparative analysis to the vibration signal,the results show that the method using the energy entropy can realize the identification of rail fastener loosening.