Study On Dynamic Behaviour And Vib-acoustic Characteristic Of Metro Train And Embedded Track System

For fast development of urban rail transit,people put forward higher request on ride comfort and reduction of vibration and noise.Metro as the main public transportation facility of urban rail transit,faces more severe challenges.Therefore,the track of the metro used a variety of vibration isolation ballastless track structure.In order to reduce the environment vibration along metro lines by using these so-called vibration isolation track structures,many problems arise in the system of metro trains and tracks,such as fierce vibration and abnormal wear of wheel/rail systems,thereby causing a series of vibration fatigue and noise of trains and tracks.Embedded track,as a kind of track structure for reducing vibration and noise,is usually designed and applicated for tram.If the embedded track is applied to the metro,it will face challenges of a higher speed,larger axle load,more complex line conditions.For our country,the matching applicability of the metro train and embedded track is also unknown.Existing dynamic models of tram train-embedded track and the metro train-common track can not be directly applied to the analysis of the dynamics and vib-acoustic characteristics of the new coupling system—metro train and embedded track system.After appling the embedded track to the metro,dynamics and vib-acoustic characteristics should be re-evaluated.It is necessary to study the dynamic behaviour and vib-acoustic characteristics of the whole metro train-embedded track system through the combination method of simulation and experiment.In view of the dynamic behaviour and vib-acoustic characteristics of the metro train-embedded track system,the following work was carried out:(1)A review of the studies all around the world on embedded track structure characteristics,dynamic behaviour and vib-acoustic characteristics was presented,in which the significance of the current work was cleared.The applicability of embedded rail in metro and some possible research directions were also discussed.(2)A detailed 3D coupling dynamic model of mero train and embedded track was developed,and a corresponding numerical simulation program was also developed This model considers three subsystems:a whole train consisting of six vehicles,a mebedded track,and wheel/rail system.This model fully considers the characteristic of embedded track structure used in metro environment,the continuous support characteristic,and the quality effect of polymer material in the groove.The coupling dynamic model of mero train and embedded track is the most comprehensive model.Based on the developed 3D coupling dynamic model of mero train and embedded track,the analysis of the dynamics of the metro vehicle and the embedded track was carried out in the highest metro operation speed and axle load condition.The corresponding research provides important reference and basis for the application of embedded track in the metro environment in our country.(3)A vib-acoustic predicted model of metro vehicle-embedded track system was developed.This model considers the characteristic of embedded track structure used in metro environment,and polymer material characteristics in the groove.The vib-acoustic predicted model of the whole system can predict the wheel-embedded track rolling noise based on the hybrid finite element and boundary element method,the interior noise of metro train running on an embedded track inside or outside the tunnel based on statistical energy method,the exterior noise of metro train running on an embedded track outside the tunnel based on the sound ray method,and the environmental vibration under considering tunnel operation conditions based on the wavenumber finite-and boundary-element methods.Based on the above developed numerical model,the dynamic behaviour and vib-acoustic characteristics of the metro train-embedded track system were studied.(4)Taking the aspects of dynamic behavior and vib-acoustic characteristics of the metro train-embedded track system as the target,the influences of the structural and material parameters of embedded track was analyzed to comprehensively improve the performance of embedded track.(5)The dynamic behaviour and vib-acoustic characteristics of the metro train-embedded track system were tested in the first embedded track test line used in metro of China.The specific tests and analysis are as follows:The natural vibration characteristics of embedded track were tested.The stability and vibration characteristics of key parts of the track and the vehicle,the wheel/rail noise,and the interior noise were tested and analyzed when the metro train ran on the embedded track.The dynamic behaviour and vib-acoustic characteristics of the metro train-embedded track system were also compared with those of the discrete supported fastener type track.Through the tests and analysis of the system,the practical application effect of the embedded track was evaluated,and the accuracy of embedded track simulation design was also verified.