Dynamics Research On Coupling System Of Medium-low Speed Maglev Train And Turnout Beam

Maglev turnout is not only an important part to ensure the normal operation of maglev train on the line,but also a weak link in the coupling vibration of train-rail system in maglev transportation line.The middle-low speed maglev turnout beam is a huge and elastic bending steel structure beam with double webs.The main material of turnout beam is structural steel,which has no damping.Due to the track irregularity and the random disturbance of maglev train operation,maglev train and turnout beam coupling vibration will be occurred easily to break track or more serious accidents.Therefore,it is of great significance to study the coupled vibration of maglev train turnout beam.In this paper,medium-low speed maglev turnout is taken as the research object.Based on the theory of maglev train and turnout beam coupling dynamics,and combined with numerical simulation and finite element method.Dynamic modeling and numerical simulation of turnout beam,vibration characteristics analysis of turnout beam,rigid-flexible coupling analysis of vehicle and turnout beam are finishes.After that,the lightweight design of turnout active beam is carried out.Firstly,the three-dimensional model of medium-low speed maglev turnout beam structure is established,and the structure composition of the maglev turnout working device and the working principle of the driving mechanism are described.Based on the basic theory of multi-body dynamics and structural dynamics,combined with the suspension system of suspension electromagnet and air spring of medium-low speed maglev train,the second-order elastic damping system of maglev train is established.It includes the elastic coefficient k₁ and damping coefficient c₁ of the air spring,the equivalent stiffness k₂ and equivalent damping c₂of the levitation electromagnetic field,and it is coupled with the maglev turnout beam to form the maglev train-track coupling vibration model.Secondly,based on the static strength and stiffness analysis,the equivalent stiffness curve of medium-low speed maglev turnout beam is obtained.Aiming at the excitation factors of track irregularity in the vehicle-rail coupling analysis model,the mathematical model of Maglev turnout beam and its F-rail irregularity is established.According to the dynamic load and coupling vibration characteristics of medium-low speed maglev train passing through turnout beam,based on Lagrange equation,a dynamic simulation model of maglev train turnout beam coupling is established.Then,using Simulink programming,the numerical simulation analysis of vehicle rail coupling dynamics is carried out by integrating the external excitation model of turnout beam and its F-rail irregularity.This simulation studies the influence of suspension system stiffness and damping coefficient,turnout beam stiffness and damping coefficient and turnout beam mass on the dynamic response of turnout beam.Thirdly,based on the frequency domain analysis method of structural dynamics,modal analysis,harmonic response analysis and response spectrum analysis of finite element theory are used to simulate the vibration characteristics of turnout beam when medium-low speed maglev train is pass on.The natural frequency and harmonic response output of the turnout beam when the maglev train passes through the turnout are solved.The results show that the first order frequency of constrained modal analysis of active beam of medium-low speed maglev turnout is 8.147Hz,which meets the requirements of medium-low speed maglev specification.Based on harmonic response output,the turnout active beam has a high amplitude near 8.7Hz,15.3Hz,48Hz and 84Hz,and the external load frequency should avoid the above frequency.Finally,based on the rigid-flexible coupling vibration analysis of maglev train turnout beam,the vibration time-domain curve of the turnout beam is obtained when the maglev train passes through the turnout.The results show that when the medium-low speed maglev train passes through the maglev turnout at the speed of 80km/h,the maximum vertical displacement of the turnout beam is 0.798mm.Because the maximum displacement is far less than the safety displacement,there is a large lightweight space.The mathematical model of optimal design is established by using the optimal space filling design method,and then the Kriging interpolation response surface method and multi-objective genetic algorithm are used to optimize the design of turnout active beam.And the optimized model is checked by finite element analysis.The results show that on the condition that the requirements of strength and rigidity are met,the total mass of the turnout active beam decreases from 13189kg to 10151kg,which is reduced by 23.03%.Then,the multi-body dynamic simulation method is used to simulate the maglev train.And the results show that when the maglev train passes through the maglev turnout,the Sperling index of the car body is 2.49,and the ride quality estimation rate is excellent.