Study On The Key Dynamic Problems In High-Speeed Train

High-speed railway that is developed quickly abroad has advantages in mass transportation capacity, lower energy consumption, safety, slight pollution and not affected by climate. Although China railway is taking measures of raising train speed at existing tracks, it can be forecasted that high-speed railway will be developed flourish before long.The radical difference between high-speed railway and conventional railway is that of the special dynamic environment. Therefore, a series of research tasks emerge from it. The dynamic performance of train system not only affects the increase of speed, but also the ride comfort and running safety. This dissertation focuses on the key dynamics problems about high-speed train that include the hunting stability, nonlinear random response and dynamic curving behavior. The research owns strong engineering background. The goal of the thesis is to form an integrated theory for high-speed train dynamics. The work of the study can instruct the design of the high-speed train in China.According to different research objectives, four kinds of vehicle dynamic models(named from model A to Model D) and two types of train dynamic models(Model E and Model F) are established in this thesis. During the modeling process of the vehicle and train systems, nonlinearities arising from wheel/rail contact geometry, wheel/rail interactive forces and suspension characteristics are fully considered. The modeling methods about vestibule diaphragm, coupler and draft gear are introduced, too. Among the six Models, Model A and Model B can be used to study the vehicle stability and curve negotiation under different track situations. Model C and Model D can be used to carry out the stability, dynamic curving behavior and ride comfort of the high-speed passenger car. Model E and Model F are three-dimension train dynamic models which consist of three cars(head car, intermediate car and tail car). They can be well used to investigate the stability, dynamic curving behavior and ride comfort of the train system.The main research work involves:(1) Based on first order ODE(ordinary differential equation) approximation theory and Hopf bifurcation theory, the nonlinear motion stability of the train is studied emphatically. The concrete method to determine Hopf bifurcation speedsof the train(vehicle) on curved tracks and tangent lines are described. To determine the equilibrium positions of the vehicle or train on curved tracks, a powerful DEPAR continuation algorithm which can improve the calculation speed obviously is adopted. The method used to determine limit cycles is also introduced in the thesis.(2) The vehicle nonlinear stability is studied by use of Model A and Model B. While Model E and Model F are used to investigate the train nonlinear stability. The effect of track stiffness and track damping on high-speed train Hopf bifurcation speed is discussed. The difference of the lateral stability between vehicle and train under the same track conditions is given. During the research course, the effect of bogie suspension parameters, track parameters, lateral link stiffness and lateral link damping between cars on train(vehicle) Hopf bifurcation speed are also educed.(3) The negotiation performance of the vehicle and the train are investigated under rigid and elastic track conditions. The effect of track stiffness, track damping, lateral link stiffness and damping between cars on train(vehicle) dynamic curving behavior are described. Increasing the lateral link damping between cars will improve negotiation performance of high-speed train. The results show that moderate lateral link stiffness between cars will do no harm to train dynamic curving behavior. The dynamic curving behavior of the high-speed train with track irregularity is studied and the corresponding conclusion is drawn.(4) The effect of track elasticity on ride comfort of vehicle and train are systematically studied in the thesis. The effects of lateral link stiffness, lateral link damping coefficient and the installatio...