Analysis Of Dynamic Interaction And Influencing Factors Between Medium And Low Speed Maglev Vehicle And Line Structure

Compared with traditional wheel rail transit vehicles,medium and low speed maglev has the advantages of no track wear,fast driving speed,less energy consumption and less environmental pollution,which has attracted countries to vigorously develop maglev rail transit technology.However,with the continuous development of maglev transportation technology,the running speed of medium and low-speed maglev vehicles is increasing,and the vibration problem caused by the interaction between maglev vehicles and line structure is becoming more and more prominent.Due to the small suspension gap of medium and low-speed maglev vehicles,when the vehicles are running on the line,they will have complex interaction,sometimes produce obvious vibration,and even lead to suspension failure.Therefore,it is of great significance to study the interaction between maglev vehicle and line structure based on field test parameters and analyze the effect of key variable parameters on the dynamic response of maglev system,so as to reduce the vibration of vehicle and line structure and further improve the safety and comfort of maglev vehicle and line structure.The main work and achievements of this paper are as follows:(1)The numerical model of single electromagnet considering PID controller is established,and the influence of suspension characteristics on magnetic rail relationship is discussed.The results show that the coil current changes linearly with the suspension gap,and the electromagnetic force does not change linearly with the suspension gap;The displacement feedback coefficient and velocity feedback coefficient have great influence on the magnetic rail relationship.With the increase of displacement feedback coefficient and velocity feedback coefficient,the vibration amplitude of suspension gap and coil current is gradually decreasing,and the acceleration feedback coefficient has little influence on the magnetic rail relationship.(2)Based on the vehicle and line structure parameters of field test,considering the action of PID feedback controller and the irregularity of maglev track as external excitation,the interaction model between medium and low-speed maglev vehicle and line structure is established,and the dynamic response results of vehicle and line structure are solved by numerical method.The results show that the natural vibration frequency of the bridge is concentrated in the low frequency band of 0-30 Hz,the natural vibration frequency of the track row is concentrated in the medium and high frequency band of 30-60 hz,the vertical relative acceleration of F rail relative to the bridge is about 5m / S2,and the relative bending strain is about 150 μ m/m;Due to the action of PID electromagnetic feedback controller,the dynamic response of the carriage is always less than that of the suspension frame.Due to the large mass and stiffness of the bridge,the dynamic response of the bridge is always less than that of the track row.The suspension gap is always maintained at about 10 mm and the fluctuation range is 1.2mm;The electromagnetic force is maintained at about 19.6k N and the fluctuation range is 2.4k N.(3)Based on the existing interaction model between maglev vehicle and line structure,the parametric analysis of maglev system is carried out,and the effects of driving speed,carriage mass,bridge stiffness and bridge form on the dynamic response of maglev system are discussed.The results show that the increase of vehicle speed will increase the dynamic response of maglev vehicle and the acceleration of bridge,but it has little effect on the displacement of bridge;The increase of carriage weight will increase the dynamic response of maglev system;The increase of secondary suspension stiffness will greatly increase the vertical acceleration of the carriage and seriously affect the safety and comfort of the vehicle,but it has little impact on the vertical acceleration and suspension clearance of the suspension frame;The increase of bridge stiffness will reduce the dynamic response of maglev system;Compared with the beam on beam scheme,the mid span vertical displacement and vehicle body vertical displacement of the beam rail integration scheme are larger,while the mid span acceleration of the bridge is smaller,but the suspension gap fluctuation of the beam rail integration scheme is smaller and its stability is better.(4)The whole process of heat exchange between environments and solar radiation is simulated by numerical method.The temperature distribution and temperature deformation of bridge structure under thermal boundary and thermal load are calculated.A maglev vehicle rail interaction model considering temperature deformation is established,and the influence of temperature deformation on the dynamic performance of maglev system is analyzed by using the model.The results show that in an ambient temperature cycle,the temperature difference between different surfaces is the largest at14:00.At this time,the temperature of the top surface of the bridge is 18 ℃ higher than that of the bottom surface of the bridge.At 17:00,the maximum vertical deformation occurs,and the maximum vertical temperature deformation is 3.86mm;Temperature deformation will reduce the vertical displacement in the middle of the bridge span,reduce the minimum suspension gap and increase the vertical acceleration of the carriage,which will have higher requirements for the suspension control system;When the ambient wind speed is small,the temperature difference between the top and bottom of the bridge is large,resulting in large temperature deformation.The increase of ambient daily temperature difference and heat conductivity will increase the temperature distribution and temperature deformation of the bridge.