Numerical Analysis On Coupled Vibration Of Medium-low Speed Maglev Vehicle-track-viaduct System

Medium-low Speed Maglev transportation has the advantages of green environmental protection,high safety,strong adaptability and comfortable riding.In recent years,it has been developing rapidly in China,Japan and Korea.At present,China has built and opened the Changsha Maglev Express line and the Beijing S1 line.Qingyuan,Chengdu and Taiyuan are also planning to build medium-low speed maglev lines.medium-low speed maglev transportation has entered the critical period of industrialization and application of engineering popularization.It is urgent to further study the problems in its engineering application.Internationally the speed of commercial medium-low speed maglev trains is less than 100km/h.But during the trial operation,there has been a strong problem of vehicle rail coupled vibration.Although the vehicle and track coupled vibration is slowed down by adjusting the suspension control parameters or strengthening the line structure in the later period,it is not entirely understood that the mechanism and characteristics of vehicle and track coupled vibration,which leads to the lack of sufficient theoretical guidance for the formulation and implementation of the vibration reduction measures.Therefore,a space coupled vibration model of medium-low speed maglev vehicle-track-viaduct is established in this paper,and the basic characteristics and laws of coupled vibration response are analyzed in order to provide theoretical support for the optimization and promotion of medium-low speed maglev traffic technology.Primarily,a coupled dynamic model of maglev vehicle-track-viaduct is built referring to the medium-low speed maglev vehical and the 25m-span girder for Changsha Maglev Express,with ANSYS parameter design language APDL.The model includes three parts,namely maglev vehicle,control system and viaduct.In the dynamic model,the vehicle is regraded as a 55-DOFmodel,which is established on the basis of the multibody dynamics theory.The track and the bridge are simulated by the finite element methord.Cantilever structure and rail joint telescopic joint are considered in F-shaped rail.The PD suspension control model based on state observer is adopted in the control system.Next,a numerical simulation program for coupled dynamics of medium-low maglev vehicle-track-viaduct is worked out.The dynamic response of the coupled vibration system under the speed of 80km/h is calculated.The basic characteristics of the space coupled vibration response are analyzed,and the results are compared with the experimental results of the existing literature.Generally speaking,the vibration of medium-low speed maglev vehicles is small,the fluctuating levitation airgap and electromagnetic force of electromagnet is small.The maglev vehicle is safe and comfortable to ride.Finally,the effects of vehicle speed,the second suspension stiffness,stiffness of rubber pad and rigidity of bridge on vibration of coupled system are discussed.The results show that vehicle speed has a big influence vehicle-rail-bridge coupled system.The acceleration of vehicle and bridge and the range of levitation airgap and electromagnetic force increase with the vehicle speed increasing,while the speed has little effect on the dynamic displacement of the bridge;The second system stiffness mainly affects the vehicle's vibration acceleration and has little influence on the bridge system;The stiffness of the rubber pad has little effect on the dynamic response of the maglev vehicle-rail-bridge system.It is mainly due to the continuous distribution of electromagnetic force,which makes the dynamic impact coefficient very small.After the rigidity of the bridge of Changsha Maglev Express is properly reduced,the vibration response of the maglev vehicle and the bridge slightly increases.However,the running stability and riding comfort of the vehicle are still good,and the safety of the vehicle is basically unaffected.