Study On Rigid-flexible Coupling Dynamic Modeling And Longitudinal Dynamic Behavior Of Railway Flat Car In Collision Process

The development theme of railway transport vehicles is to develop towards high speed,heavy load and light weight.The influence of elastic structure deformation on the dynamic performance of the vehicle system under high speed operation should be paid attention to,especially the influence on flat cars with low vertical stiffness.To this end,for the railway flat car,the dynamic performance of rigid-flexible coupled vehicle considering the flexibility of the vehicle body was studied.Combined with the theory of multi-body dynamics,the rigid-flexible coupled model was established.According to the structure of the car body,a model of the flexible car body is established through the transformation of its coordinates by modal superposition method,and further connected with other rigid bodies in the dynamics software to integrate the rigid and flexible coupling model.The dynamics analysis of the two established models was carried out,and the unsmooth spectrum of the traditional three main lines was used as the excitation to compare the vibration of the car body when a single vehicle passes through the straight and curve,the downward transmission law of the car body vibration,and the dynamic characteristics of the single vehicle and the three-section short train,the rigid-flexible coupling and the multi-rigid body three-section short train.Through the collision analysis of different grouping models,the dynamic response of the affected vehicles is simulated when the impact is connected,and the dynamics of the vehicles under the action of longitudinal force is studied.First of all,the transverse and vertical vibration of the rigid-flexible coupling model is slightly greater than that of the multi-rigid body model.Due to local deformation of the flexible body in operation,the vibration contrast from the body to the wheel will be attenuated to different degrees due to the damping effect of the central suspension.When a rigid-flexible coupling bicycle and a multi-rigid body bicycle pass through a straight curve at different running speeds,the maximum lateral vibration acceleration of the flexible body increases by about 4% and 1%,and the maximum vertical vibration acceleration increases by about 18% and 7%,respectively,compared with the rigid body,which is related to the bending and torsional deformation of the flexible body.The vertical ride stability index increases with the increase of speed,and the ride stability index of flexible car body is greater than that of rigid car body.Furthermore,the dynamics indexes of rigid-flexible coupled single vehicle and three-car short marshalling train,multi-rigid body single vehicle and three-car short marshalling train,and rigid-flexible coupled model and multi-rigid body three-car short marshalling model are compared.It can be concluded that the vibration acceleration and running stability index of single vehicle are greater than that of the three-car short marshalling train.The maximum transverse vibration acceleration difference between single vehicle and three-car marshalling is about 36%,and the maximum vertical vibration acceleration difference between single vehicle and three-car marshalling is about 38%,indicating that the connecting device between vehicles inhibits the vibration of the car body.The maximum lateral and vertical vibration acceleration of rigidflexible coupled three-section short marshalling train is 11% higher than that of the multi-rigid body model,and the maximum vertical vibration acceleration is 30% higher than that of the multi-rigid body model.Finally,the vehicle dynamic performance indexes of the rigid-flexible coupling model and the multi-rigid-body model are studied and compared.Through different collision formation forms and different impact speeds,the differences between rigid and flexible car bodies are obtained: The maximum coupler force and vibration acceleration of different collision grouping models increase with the increase of impact velocity.The maximum coupler force of multi-rigid-body vehicle model increases about 8% compared with the rigid-flexible coupling model,and the maximum buffer travel of multi-rigid-body vehicle model increases about 9% compared with the rigidflexible coupling model.The stick-slip area decreases with the increase of impact velocity.The adhesion zone of impacted vehicle decreases with the increase of braking torque.The longitudinal vibration acceleration of rigid car body is higher than that of flexible car body,which is about 6%,indicating that the elastic structure of flexible car body can buffer the longitudinal vibration.The vertical vibration acceleration of the flexible car body is higher than that of the rigid car body,which is about 15%,indicating that the bending deformation of the elastic car body affects the vertical vibration of the car body.Under the longitudinal force,the longitudinal vibration accelerations of different parts of the rigid and flexible vehicle body are not significantly different when the vehicle passes through the straight and curve,while the vertical vibration acceleration of the flexible vehicle body is greater than that of the rigid vehicle body,about 20%,and the maximum vertical vibration acceleration of the two ends of the vehicle body is greater than that of the middle part,so the vibration acceleration is within the safe range.