Research On Rigid-flexible Coupling Dynamics Of The High-speed EMUs Trailer Bogie

High-speed passenger transport and heavy-duty freight have been two major themes of the modernization of railway transportation.With the continuous increase of the railway train speed,the influence of structural vibration on vehicle dynamic performance is more and more significant.Due to weight reduction,some of the components show rigidity insufficient,the aggravated elastic vibration and the resonance.So it is necessary to carry out research on the rigid-flexible coupling dynamics.As an important component of railway vehicle,the structural vibration of the bogie has an important influence on the dynamic performance of the train.In this paper,the wheelset and frame of a certain high-speed EMU trailer bogie were treated as flexible bodies,and three kinds of rigid-flexible coupling dynamics models were built,including the rigid-flexible coupling dynamics model of wheelset,the rigid-flexible coupling dynamics model of frame,the rigid-flexible coupling dynamic model of bogie,based on the substructure analysis method and multi-body dynamics theory,by using the finite element software ANSYS and the multi-body dynamics software SIMPACK.By comparing the rigid-flexible coupling dynamics model and the multi-rigid body dynamics model,the influence of the elastic vibration of the wheel and the frame on the dynamic performance of the vehicle system is studied.This paper firstly carried on the modal analysis of bogie wheelset and frame,obtaining the natural frequency and natural mode,thus providing theoretical support for the research of rigid-flexible coupling dynamics.Then in order to evaluate the hunting stability of vehicle,the non-linear critical velocity of the trailer was calculated by the method of speed reduction,with the lateral displacement-time relation of the first place wheelset.The difference of the indexes of vehicle stability between rigid flexible coupling dynamics model and multi rigid body dynamic model under four different speed levels were studied with the lateral and vertical acceleration of the junction of the body and the mass center of the bogie and thesperling index.According to the design standard of China's high-speed railway about the radius of the curve,the curve performance of the vehicle was evaluated by using the derailment coefficient,unloading ratio,wheel/rail lateral force and lateral wheel-axle force under four different radius of curve.At last,the influence of structural flexibility on the vibration acceleration of vehicle was studied with an example of wheelset.The results showed that,when considering the flexibility of the bogie components,the critical speed of the vehicle reduced,the more flexible parts,the more decline of critical speed.Compared to the multi rigid body system of the vehicle,the comfort index of the rigid-flexible coupling vehicle system increased in varying degrees.At the same radius,the elastic vibration of the wheelset led to the unloading ratio reduction,wheel/rail lateral force reduction and lateral axle force reduction,and the elastic vibration of the frame led to unloading reduction,wheel/rail lateral force reduction and lateral axle force increase.When the high-speed train is running,the high-frequency orbit excitation will stimulate the elastic vibration of the wheelset,which will have some influence on the dynamic performance of the vehicle system.Therefore,the rigid-flexible coupling dynamics of the vehicle can reflect the vibration characteristics of the vehicle better.