Analysis Of Spatial Coupling Vibration Of The Vehicle-track System

With the continuous innovation and progress of high-speed railway technology,the operation speed of high-speed trains has been further improved,and the wheel-rail interaction has become increasingly fierce.The early research method of separating vehicle dynamics and track structure vibration is not enough to accurately simulate the vehicle-track coupling mechanism.Under this background,vehicle-track coupling dynamics came into being.At the beginning of the study,it was limited to the lack of computer computing power and the lack of theoretical research.The study of vehicle-track coupling system dynamics was limited to the vertical coupling system dynamics simulation analysis.In recent years,with the continuous improvement of computer computing power and the continuous deepening of vehicle dynamics,track dynamics and wheel-rail relations,researchers began to study the vehicle-track spatial coupling dynamics.Based on the finite element method,this paper establishes the dynamic model of the vehicle-track space nonlinear coupling system,and proposes a method to solve the vehicle-track space nonlinear coupling system dynamics by combining the trace method with the cross iteration method.The main research work and innovation achievements are as follows:(1)The three-dimensional vehicle model and the motion equation of the vehicle subsystem are established,and the three-dimensional slab track model and the motion equation of the track subsystem are established.Three-dimensional vehicle model is composed of vehicle body,bogie and wheel set,in which the car body and the bogies,and the bogie and the wheelsets are connected by secondary suspension and primary suspension,respectively.The force analysis of each component of the vehicle model is carried out to obtain the motion equation of the vehicle subsystem.The three-dimensional slab track model is composed of rail,track slab,fastener system,CA mortar and subgrade.The rail is simulated by spatial beam element,the track slab is simulated by the three-dimensional solid element,the rail fastener is represented by the 3D discrete viscoelastic damping element,and the CA mortar and subgrade are represented by the viscoelastic damping element with equivalent continuous support.The track subsystem is composed of the three-dimensional slab track models,and the motion equation of the track subsystem can be obtained by using Lagrange equation.(2)Calculation method of wheel-rail contact relationship in straight track.The calculation method of the wheel-rail contact relationship in plane is established,and the detailed steps of solving the wheel-rail contact relationship in plane by using the "minimum distance method" are summarized.Based on the MATLAB platform,a program for solving the wheel-rail contact relationship in plane is developed,and the correctness of the algorithm is confirmed by comparing with the existing research.In order to further study the wheel-rail contact space problem,the "trace method" is used to solve the left and right wheel contact traces and calculate the wheel-rail contact point coordinates on the left and right rails.Use the "minimum distance method" to scan the wheel-rail contact point position.The normal force of wheel-rail contact is solved based on Hertz nonlinear formula,and the normal force is decomposed in the overall coordinate system to obtain the component force in three directions.(3)Dynamic Analysis of the high speed train–track spatial nonlinear coupling system.A vehicle-track spatial nonlinear coupling vibration model is established,and a method of solving the high speed train–track spatial nonlinear coupling system dynamics is proposed by combining the "trace method" with the "cross iteration algorithm",which realizes the synchronization of wheel-rail contact point search and vehicle-track nonlinear coupling equation solution,and improves the efficiency of numerical analysis.Based on the MATLAB platform,a dynamic analysis program VT＿3DCI for the high speed train–track spatial nonlinear coupling system is developed.Using this program,the influence of train speed and track irregularity on the dynamic response of high speed train-track system is studied.The Vshaped irregularity is used to simulate the local irregularity of rail weld joint defects,and the single-wave cosine function is used to simulate the track twist irregularity.The influence of the above two kinds of irregularity on the dynamic response of high speed train-track system is analyzed by using VT＿3DCI program.(4)Simulation software for vehicle-track spatial nonlinear coupling system.Based on the "vehicle-track spatial nonlinear coupling vibration theory",the "three-dimensional vehicletrack nonlinear coupling system finite element software" was developed.The software can realize the dynamic calculation of vehicle-track spatial nonlinear coupling system under various track irregularities,realize the synchronous calculation of derailment coefficient and wheel load reduction rate,and output the results in the form of pictures and save the final response in the form of files.The development of this software greatly facilitates the dynamic analysis and calculation of vehicle-track spatial coupling vibration.