Research On Coupling Dynamics For Suspension Frame-track Of Long Stator Maglev Train

The suspension frame is one important part of the magnetic levitation train running mechanism with complex operating conditions.It needs to carry the whole maglev train,tow the train forward and steer the train.Considering that the track irregularity will definitely cause train vibration,the suspension frame needs to reduce the vibration.Its dynamic performance has a direct influence on the stationarity and safety of train.It is neeessary to research the dynamic characteristics of suspension frame.In this paper,the long stator maglev train suspension frame is taken as the research object.Based on the vehicle-rail coupling dynamics theory,the research on suspension dynamics modeling,suspension parameter analysis and suspension random vibration analysis are carried out.Firstly,the structure and force of the suspension frame are analyzed.The relationship between the railway track and the suspension electromagnet is simplified into a linear spring damping system.The basic principle of structural dynamics is used to construct the suspension-track vertical coupling system and the dynamic model including the bouncing,pitching and rolling directions of vibration is established.Combined with the D’Alembert principle and the virtual displacement method,the group differential equations of the suspension system are derived.Secondly,the classification and components of the track irregularity are analyzed.A simple harmonic mathematical model of track irregularity deterministic excitation is established,which provided input excitation for suspension parameter analysis of suspension system.The railway track spectrum function suitable for high-speed vibration test of vehicles is selected to carry out the time-domain numerical simulation by means of periodic diagram method and inverse Fourier transform.The time-domain model of railway track high and low random irregularity is obtained,which provided input excitation for the random vibration response analysis of the coupled system.Thirdly,a dynamic simulation program is writing using the fast display integration method.Using the simple harmonic mathematical model as the input excitation,the four suspension parameters are analyzed in turn,namely the magnetic gap parameters,the electromagnet-suspension parameters,the left-right suspension frame parameters and the front-rear suspension frame parameters.Comparing the vibration response of suspension electromagnet and suspension frame unit under different damping conditions,the reasonable suspension parameters’ value range are explored.Finally,based on suspension parameter analysis,a set of suspension parameters within a reasonable range is selected.The time domain and frequency domain response of the suspension frame are analyzed by using the time domain model of random irregularity of the track as the input excitation.The results of time domain analysis show that the vibration response of the suspension frame structure can be converged under the excitation of the track irregularity,the amplitude range is reasonable,and the suspension parameters are feasible.The results of frequency domain analysis show that the main frequency of the track high and low irregularity excitation should be away from the frequency range of 0.5~1.5Hz to avoid the resonance of the suspension frame floating motionIn conclusion,the theoretical analysis and simulation study on the vertical dynamics of the suspension of the maglev train are carried out.The research results have reference value for the suspension parameters selection of the suspension frame,which is of great significance for improving the running stability of the vehicle and the control of the track irregularity.