Study On The Hunting Stability In High-Speed Vehicle

Because of the high-speed railway has the advantages of mass transportation capacity, lower energy consumption, safety performance is high, slight environmental pollution, the no affected by climate, So at home and abroad, the high-speed railway gets fast development. With the reforming of our country in existing tacks and the new construction for high-speed railroads, High-speed rail playing the more and more major role in China's economy and life.The stability of vehicle system have been found early in the initial period of railway transport business development, but the reason of the stability of high-speed vehicle system which different between the normal vehicle movement is its special high-speed in the dynamic environment.The researches of hunting stability for High-speed vehicle from initial linear model or linearized mathematical model to considering more nonlinear factors in the nonlinear model now, from its local stability early to the global stability and chaotic phenomenon in present, the depth of its research is more deeper,and the factors are considered more and more closer to actual engineering application.According to the multi-body dynamics method, using dynamic simulation software SIMPACK establish the multi-body dynamics model of vehicle system, research influence of vehicle system structure parameters on the linear and nonlinear critical speed and the Hopf bifurcation types of vehicle system.This paper mainly applied multi-body dynamics method, using dynamic simulation software SIMPACK establish vehicle system, more mechanics model of vehicle traffic system structure parameters of linear and nonlinear critical speed of vehicle system, and the influence of Hopf bifurcation types.The main job incoleves:(1) Based on the research of the multi-body dynamics method for the wheel/rail relations and the structural parameters of vehicle, establish vehicle dynamics simulation model.(2) Introduce the related theory of hunting stability of the vehicle system, Analyze the reasons of Hopf bifurcation in vehicle system, and analyze the methods of how to determine the linear and nonlinear critical speed in simulation,and how to establish the graph of the Hopf bifurcation.(3) Analyze when the vehicle system with several different Equivalent conicity and track gauge.how the hunting stability of vehicle system, the critical speed and the types of Hopf bifurcation changes, draw with the type of equivalent taper the critical speed reduce vehicle system, the linear critical velocity and thenonlinear critical of velocity Vehicle system's difference gradually decrease; Knowing that as the Equivalent conicity decrease the critical speed of the vehicle system is increased, the types of Hopf bifurcation have the trend of froming subcritical bifurcation to supercritical bifurcation; Along with the increase of the track gauge, the critical speed of vehicle system is increase, when the track gauge increased to a certain value, the vehicle system appeared supercritical bifurcation, but the critical speed loss is bigger.(4) Establish the hypothetical spring-damping series model of Yaw damper, analyze the influence of delay time and limit frequency on the critical speed Hopf bifurcation types of vehicle system, it is concluded that the conditions of the vehicle system appeared supercritical bifurcation, provided references for the high-speed vehicles running and designing.(5) Analyze the influence of primary and secondary spring stiffness, secondary damping on the critical speed of vehicle system, the research shows that the increase of primary and secondary spring stiffness follow the critical speed of vehicle system first increased, later decreased, the fasted critical speed can't be reached with bigger or smaller stiffness; the secondary stiffness and damping also have a big effect in the critical speed of vehicle system.