Numerical Analyses Of Coupled Vibration Between Medium-low Speed Maglev Vehicle And The Switch Girders In The Branch Route

In recent years,the construction of medium-low speed maglev transportation system has been carried out in cities across the country,and it has gradually entered into the lives of citizens because of its unique advantages such as small area,low cost and low noise.Switch is an important part of maglev traffic,which is used for vehicle line change or connecting depot line and main line.Compared with the normal line,the steel structure turnout has smaller self–weight and damping and weaker lower constraint,and is prone to strong coupling vibration when the maglev passes through.After years of in–depth research by experts and scholars,some reasons for the strong coupling vibration between maglevs and switches and the corresponding vibration reduction measures have been explored.At present,the existing research and test pay more attention to the train passing through the switch in a straight direction,and there is little research on the coupling vibration when the vehicle passes through the turnout in the branch route.In fact,it has been found on the operation line that the maglev train has obvious lateral shaking when passing the switch laterally,and there are scratches on the outside of the F–rail of the switch,indicating the mechanical collision and friction between the lateral stop and the F–rail.In order to explore the technical countermeasures to improve the operation safety of Maglev switch and the stability of vehicle passing through switch,this thesis studies and summarizes the coupling vibration law of maglev train and switch girders in the branch route,in order to provide theoretical basis and application reference for the safe application and structural optimization of medium-low speed maglev traffic switch system in China.Firstly,combined with a domestic medium-low speed maglev tourist line project,the coupling dynamic model of maglev vehicle and switch girders in the branch route is established.The dynamics model of maglev train considering forced steering mechanism and the lateral stop of the electromagnet is established by using UM.The finite element model of switch girders in the branch route including active switch,follower switch and transition device between switches(angle dividing device)is established by using Hypermesh,and the PID control system is built by Matlab/Simulink.Secondly,after verifying the vehicle model and switch model according to the field measured data,the dynamic response of vehicle system and switch structure when the maglev train pass through the switch girders in the branch route at different speeds is simulated and calculated by UM software.The results show that when the train passes through the switch girders in the branch route at the speed of 10km/h,the dynamic indexes of the coupling vibration system meet the requirements,but there are many collisions between the lateral stop and the F–rail.When the crossing speed exceeds 15 km/h,the lateral acceleration of the car body has exceeded the provisions of the specification.At the same time,the suspension gap at the front end of the first levitation bogie fluctuates greatly,which has the risk of suspension instability.Therefore,the crossing speed of the train should be carefully selected in practical engineering application.Finally,compared with the simulation results of 10 km/h,the effects of switch girder structure parameters and vehicle system parameters on the coupling vibration response are explored.The results show that if the angle dividing device is not set,the lateral dynamic response of the switch girders and car body increases significantly,and the lateral acceleration of the front end of the car body increases from 1.50 m/s~2 to 2.11 m/s~2,which is close to the limit specified in the specification.After reducing the switch angle,the lateral dynamic response of the switch girders is reduced.and the responses such as the lateral acceleration of the car body and levitation bogie and the lateral displacement of the magnet are reduced.However,the number of trolley supported by the driving beam has little effect on the coupling vibration response.increasing the stopping rubber clearance and sliding support distance can reduce the lateral dynamic response,and the effect of increasing sliding support distance is particularly obvious.When the sliding support distance is expanded by 30 mm,the lateral dynamic response of the long-span girder and the vehicle system is significantly reduced,the lateral displacement of the front end of the first levitation bogie is reduced from 27.28 mm to16.58 mm,the risk of suspension instability is reduced,and the interaction between the stopping rubber and the F-rail is weakened.