Coupling Dynamic Analysis Of Vehicle-track Considering Multiple Flexibility Bodies

With the greatly improved of the running speed of the train,higher requirements are put forward for the calculation accuracy of vehicle system dynamics.The traditional method of considering wheelset,frame and track as rigid body or only one of them as flexible body to analyze the running stability and smoothness of vehicle system needs to be improved urgently.In this thesis,the dynamic behavior of the vehicle-track coupling system with multiple flexible bodies is considered.This thesis takes the wheelset and frame of CRH2 high-speed passenger vehicle as the research object.Based on the theory of multi-rigid body dynamics and rigid-flexible coupling dynamics,the wheelset,frame and track are considered as flexible bodies.Combined with the finite element analysis software ANSYS and multi-body dynamics software UM,the dynamic response of the vehicle system is studied under multiple flexibility bodies.Based on the finite element software ANSYS,the modal analysis of the wheelset and the frame is carried out,and the corresponding stiffness matrix is calculated,and the flexible body model of the wheelset and the frame is obtained.Considering the non-linear links such as wheel-rail contact geometry,lateral stopper,lateral and vertical damper,the multi-rigid body dynamic model of vehicle system,rigid-flexible coupling dynamic model of considering only wheelset flexibility and simultaneously considering wheelset and frame flexibility are established successively.The vibration response of wheelset of the multi-rigid-body dynamic model and the rigid-flexible coupling dynamic model considering the flexibility of wheelset are simulated and calculated,when this two model are coupled with the massless rail,inertial rail and flexible track,respectively,and the corresponding non-linear critical speed is obtained.Six typical working conditions are selected reasonably,and the differences in the effects of wheelset rigidity and flexibility on the dynamic performance of the vehicle system are compared and analyzed.The results show that the elastic effect of wheelset reduces the non-linear critical speed of the vehicle system.Under six typical working conditions,the elastic effect has different effects on the vehicle dynamic performance.Finally,the vibration response of the wheelset and frame of the multi-rigid body dynamics model and rigid-flexible coupling dynamic model under multi-flexible bodies are compared and calculated,and the dynamic performance differences between the multi-rigid body model and the multi-flexible model are compared and analyzed.The effects of lateral stiffness of fasteners and vehicle running speed on wheel-rail contact characteristics of the vehicle system under multi-flexible bodies are studied.The influence of multiple flexibility bodies on the running stability and smoothness of the vehicle system is explored.The results show that the derailment coefficient,wheel-rail lateral force and wheel axle transverse force of the vehicle system are significantly increased by multi-flexible bodies,and the maximum increases are 3.6 times,2.4 times and 0.77 times under six working conditions,respectively.The Sperling stationarity index of the vehicle body appears opposite phenomenon in the horizontal and vertical directions under the influence of multi-flexible bodies.The Sperling stationarity index of the vehicle body decreases horizontally direction with a maximum decrease of 9.5%,while the Sperling stationarity index of the vehicle body increases in vertical direction with a maximum increase of 16.6%.