The Modeling And Coupling Vibration Analysis Of Gear Transmission And Bearing System For High-speed Train With Operation Environment

With the continuous increase of service mileage and quantity of high-speed trains in China,the complex operating environment seriously challenges the service reliability of the key components and affects the operation safety of such train.As the essential components of high-speed trains,the gear transmission system and the axle-box bearing directly suffer the loads from the vehicle and the excitations from wheel-rail interaction,and its dynamic characteristics directly affect the vehicle dynamic performance.Therefore,it is of great significance to understand the vibration behavior of gear transmission systems and axle-box bearings during operation for ensuring the operation safety of high-speed trains.Traditional vehicle dynamics research focuses on vehicle vibration behavior,as well as key components such as carbody,bogie frame and wheelset.However,few studies focus on high-speed train gear transmission system and axle-box bearing,especially with the consideration of their operation environment.To meet this gap,based on the vehicle-track coupled dynamics theory,gear transmission system dynamics theory and bearing dynamics theory,this thesis comprehensively studies the vibration characteristics of high-speed train gear transmission system and axle-box bearing,including the following section:Firstly,based on the structural characteristics and working mechanism of high-speed train gear transmission and axle-box bearing,the coupling effects between gear transmission subsystem,axle-box subsystem and vehicle subsystem is theoretically derived,and then the high-speed train vehicle-track coupled dynamics model comprising gear transmission and axle-box bearing is established.Compared with the traditional vehicle-track coupled dynamics model,the coupling vibration effects of the gear transmission system,the axle-box bearing and the vehicle-track system are considered for the first time.The nonlinear characteristics,such as the gear time-varying meshing stiffness,the gear backlash,the bearing nonlinear stiffness and clearance are simulated,which performs the vibration characteristics of the gear transmission system and the axle-box bearing under the vibration environment during operation.The numerical results are compared with the results of the traditional vehicle-track coupled dynamics model to make the validation of the proposed model.Then,based on the established vehicle-track coupled dynamics model,the effects of the track irregularity,gear meshing and cross wind on the axle-box bearings are investigated in the time domain and frequency domain.The unsteady wind loads acting on the carbody are derived based on the fluid-induced vibration theory.Combine with the Monte Carlo method,stochastic excitations and the vehicle-track coupled dynamics model,the random responses of the axle-box bearing under stochastic cross winds and track random geometric irregularities are studied.Then,the field experimental tests are implemented to validate the proposed coupled dynamics model.Secondly,aiming at the wheelset failure phenomenon(wheel flatness and wheel polygon wear)frequently occurs during vehicle operation,based on the high-speed train vehicle-track coupled dynamics model considering the axle-box bearing,the effects of wheelset failure on the axle-box bearing are analyzed.As the excitation input of the vehicle-track coupled dynamics model,the wheel flatness is modeled to reveal the vibration characteristics of the axle-box bearing with different flat lengths and different speeds.Furthermore,the wheel polygonal wear is measured by experimental tests,and the measurement data and its statistical results are obtained.Based on the theoretical model and measured polygonal wear,the effects of polygonal wear depth,order and running speed on the axle-box bearing are analyzed.Then,based on the high-speed train vehicle-track coupled dynamics model considering the traction drive system,the influence of the gear meshing on the vehicle-track coupled system is studied.Further,based on the established vehicle-track coupled dynamics model including the transmission system gear and its bearing,the coupled vibration behavior analysis between the gear pair and bearing in the vibration environment are implemented.At the same time,as one of the common faults of the transmission system,gear eccentricity is involved in the coupled dynamics model and its effects on such system are also studied.The torsional vibration characteristics of the transmission system under gear cracking,wheel flatness and wheel polygonal wear are studied to provide a basis for wheel fault diagnosis and health condition monitoring.Next,the rig tests are carried out to investigate the effects of 20^thorder wheel polygonal wear on the gearbox.Finally,based on the vehicle dynamics theory and the gear dynamics model,the multi-body system dynamics model of the motor car and the trailer is established in the SIMPACK environment.In order to reflect the vibration characteristics of the vehicle more realistic,the model considers the non-linear factors such as traction characteristics,time-varying mesh stiffness,friction and gear backlash.Then,the vehicle multi-body system dynamics and the wheel wear prediction model are combined to perform the wheel tread wear prediction.Based on the proposed model,the wheel wear difference and its mechanism between the motor car and trailer are analyzed.Moreover,the vibration characteristics evolution of the gear transmission system with different wheel wear conditions is studied within a wheel repairing cycle.