Study On Snakelike Stability And Hopf Bifurcation Of High Speed Bogie System Considering Wheelset Gyroscopic Effect

In the past few years,serpentine locomotion,an inherent attribute of vehicle system,has significantly challenged the running stability,ride comfort and safety of vehicle system with the development of high-speed train technology.In this context,the establishment of a vehicle system dynamics model closer to the actual state and the study of the influence of nonlinear factors in the vehicle system on the serpentine stability of the vehicle system have attracted widespread attention and evolved into a hot research direction.In this work,the lateral dynamic model of single wheelset system and bogie system are studied mainly from the point of view of wheelset gyroscopic effect,Hopf bifurcation based on single parameter and degenerate Hopf bifurcation based on two parameters.The results are shown as:1)The major parameter affecting the wheelset gyroscopic effect is the lateral moment of inertia of the wheelset system.When the vehicle system constraints are consistent,the greater the lateral moment of inertia of the wheelset system,the greater the corresponding linear critical speed and nonlinear critical speed of the vehicle system,indicating that the wheelset gyroscopic effect will improve the serpentine motion stability of the vehicle system.2)When the equivalent taper of the wheelset system is nominal equivalent taper,the degenerate Hopf bifurcation based on two parameters(the primary longitudinal stiffness of the wheelset system and operating speed of the wheelset system)will occur in the wheelset system with and without gyroscopic effect under different stiffness and damping constraints,that is,the transformation process from subcritical Hopf bifurcation to supercritical Hopf bifurcation will occur.3)When the equivalent taper of the wheelset system changes the equivalent taper fitting function,for the measured standard tread,the degenerate Hopf bifurcation based on two parameters(the primary longitudinal stiffness of the wheelset system and the running speed of the wheelset system)will occur in the wheelset system with and without gyroscopic effect under different stiffness and damping constraints,that is,the transformation process from subcritical Hopf bifurcation to supercritical Hopf bifurcation will occur.However,for the measured wear tread,the degenerate Hopf bifurcation based on two parameters(the primary longitudinal stiffness of the wheelset system and the running speed of the wheelset system)will not occur in the wheelset system with and without gyroscopic effect under different stiffness and damping constraints,that is,the transformation process from subcritical Hopf bifurcation to supercritical Hopf bifurcation will not occur,and it will always be in the state of subcritical Hopf bifurcation.4)It is proposed for the first time that the nonlinear and non-smooth damping force in the anti-snaking shock absorber is fitted as a smooth function of the damping force and the relative velocity between the car body and the frame.Under the smooth fitting function of the damping force,the degenerate Hopf bifurcation based on two parameters(the primary longitudinal stiffness of the wheelset system and the running speed of the wheelset system)will occur in the bogie system,that is,the transformation process from subcritical Hopf bifurcation to supercritical Hopf bifurcation occurs.