Random Vibration Analysis Of Vehicle-track-bridge Coupling System

High-speed railway is developing fast worldwidely because of its high safety, high speed, comfortbility and low cost. Bridge is one of the most significant infrastructures of the high-speed railway. When a high-speed vehicle passes through the bridge, interactive vibrations among the vehicle-track-bridge coupling system will occur. As the most important excitation source for the vibration of the coupling system, the stochastic irregularity of the track has a vital influence on the ride quality of the vehicle. The interactions from the coupling system, which are caused by the track irregularities, become more severe with the increasing of vechicles’ operating speed. Therefore, the random vibration analysis of the vehicle-track-bridge coupling system is significantly necessary.In this paper, a comprehansive vehicle-track-bridge coupling model was developed. The vibration equations of vehicle subsystem were derived from the D’Alembert’s principle; the vibration equations of the rail and bridge subsystems were created base on the bending dynamics of beam. For the wheel-rail subsystem, the vertical interactions were simulated base on the linearization of Hertz contact theory to generate differential equations of the vibrations from the coupling system. Those equations were expressed with mathematical matrixes. In this study, the random irregularity was considered as a stationary random process and the German high-speed track spectrum was selected as the excitation source of the coupling system. To avoid the calculation of structure vibration mode and the numerical integral calculation, the pseudo-excitation method and the direct Ritz method were combined to calculate the vibration characteristics of the vehicle, track and bridge under the random irregular excitations. Using trigonometric series method, the power spectrum of system response is transformed into time-domain. The influence of the level of track irregularity, the train running speed and the train suspension parameters on the dynamic response of the coupling system are analysed. The ride qualities and the sensitive ranges of the irregularity wavelength at different vehicle velocities are presented. Results reveal that the Sperling index goes higher with the increasing of the vehicle velocity, which results in the longer wavelength and wider range of the vehicle sensitive irregularity.The research paper can be used as technical reference document for the structure design of the high-speed vechicle and matainance of the track and bridge.