Vehicle Dynamics Study Of A Magnetic Levitation Test Vehicle In Acceleration Phase

As an emerging mode of transportation,maglev vehicles have the advantages of faster speed,lower noise and less pollution than traditional rail trains,and have a nice prospect.In order to ensure the safety and stability of maglev vehicles,its dynamic characteristics have become the focus of current research in the industry.Combined with the task requirements of the CRRC cooperation project "High temperature Superconducting Maglev Transportation System Development Strategy and Technology Research Project--Simulation Analysis of the Contact Dynamics and Rigid-Flexible Coupling of rubber wheel",this paper carried out the dynamics research of the maglev test vehicle.In the acceleration stage before entering the suspension state,the maglev test vehicle mainly relies on the running wheels to move forward on the walking surface of the U-shaped track.This paper focuses on the dynamic response of the test vehicle during acceleration,explores the influence of different working conditions and design parameters on the dynamic performance of the test vehicle,and evaluates its safety and stationarity.The main research results of the paper include:(1)Based on SIMPACK,vehicle dynamics analysis model,track irregularity model and tire model suitable for maglev test vehicle in acceleration stage were developed.Based on the theory of vehicle system dynamics,the differential equation of vehicle acceleration stage was established after simplifying the test vehicle.Based on SIMPACK,a dynamic model of maglev test vehicle running on U-shaped track at acceleration stage was established.In the model,Pacejka Similarity tire model is used to simulate vehicle running wheels,Bump Stop force element is used to simulate guide wheels,and road roughness incentive model is input through 3D road rdf file.The rdf file is generated using triangle rules based on actual measurements of track roughness.(2)Based on the vehicle dynamics model,the effects of road roughness,traction force and load on the dynamic response of the magnetic levitation test vehicle at acceleration stage were studied.The results show that the vibration of the front and rear measuring points of the vehicle is similar under the excitation of road roughness,and the collision between the guide wheel and the side wall should be paid attention to.Road roughness has obvious influence on vehicle dynamic response.High precision road surface can significantly reduce vehicle vibration and improve running stability.Increasing traction force of superconducting magnet will lead to increased vibration of vehicle and obvious collision,which should be avoided as far as possible.Increased load will not worsen vehicle performance,the test vehicle has a good load performance.(3)Based on the vehicle dynamics model,the influence of vehicle parameters on the dynamic performance of the maglev test vehicle at acceleration stage was explored.Vehicle parameters include running wheel parameters,guide wheel parameters,first-series suspension parameters,second-series suspension parameters,and track sidewall clearance.The results show that reducing the radial stiffness of running wheel has obvious effect on improving running stability and collision condition.Moderately reducing the radial stiffness of guide wheel can effectively improve the vehicle collision condition and reduce the collision times and maximum collision force.Reducing the vertical stiffness of the first spring can improve the lateral and vertical vibration of the vehicle,while the vertical damping of the first spring has a relatively weak effect on the dynamic response of the vehicle.Reducing the vertical stiffness of the second series spring can improve the vertical ride of the vehicle,reducing the vertical damping of the air spring can improve the vertical ride of the vehicle,but will worsen the lateral ride of the vehicle.Increasing the horizontal stiffness or damping of the air spring can improve the lateral dynamic performance of the vehicle.The recommended clearance between guide wheel and track side wall is between 4mm and 6mm.