Coupled Vibration Characteristics Analysis And Experimental Research Of Medium And Low Speed Maglev Train-turnout

Medium and low speed maglev vehicle adopts active control technology,in order to maintain the rated gap between the vehicle and the track to achieve stable levitation of the vehicle,the suspension control system needs to adjust the suspension current in real time.The vehicle,track beam and control system together form a self-excited vibration system,when the system’s coupled vibration response is too large or does not converge,severe vehicle-rail coupled vibration will occur,which will affect the quality and safety of train operation.The medium and low speed maglev vehicle turnout is an integral part of the track,due to the movable section of the track at the turnout section,the mass per linear meter is significantly lower than that of the normal track,it is a weak link with prominent vehicle-rail coupling vibration,the train turnout coupling vibration problem has occurred on the turnout of Changsha maglev Express Airport Station and Zhuzhou Maglev Test line.Aiming at the medium and low speed maglev train turnout dynamic coupling system,this thesis studies the influence of the key design parameters of the system on the train turnout coupling vibration through the combination of theoretical research,simulation calculation and field test,such as vehicle speed,vehicle load,vehicle marshalling,suspension parameters,control parameters,turnout vertical support stiffness and turnout structure damping ratio.On the one hand,it briefly analyzes the essence of the existing train-turnout coupling vibration problem,on the other hand,it also provides theoretical support for the subsequent speed increase of medium and low-speed turnout.The work carried out and the main conclusions obtained are as follows:1)For the vehicle system,the force analysis of its main components is carried out,its motion equation is deduced,and the dynamic model of the vehicle system is established.The calculation results show that the vehicle body has a variety of independent and composite motion vibration modes,and its natural frequency is low.For the turnout system,a turnout finite element model considering the structure of driving beam,driven beam and cribbing beam is established based on ANSYS platform.The calculation shows that the turnout has rich modal shapes including transverse,vertical and torsional modes.The separate study of the two subsystems lays a foundation for the subsequent establishment of a complete train turnout dynamic model.2)Considering the basic characteristics of vehicle,track beam and control system,a simplified single-point analysis model of train track coupling dynamics for principle analysis is established.Using this model,the effects of different vehicle secondary suspension frequency,control system characteristic frequency and track characteristic frequency on the floating performance of the system are studied.Secondly,using external different frequency loads to stimulate the excitation of the vehicle and the characteristic frequency of the line to the system,the longitudinal motion simulation of single point system is realized,and the relationship between system vibration and system frequency and excitation frequency is further analyzed.The single point system not only reveals some basic laws of vehicle suspension,but also provides direct data support for the establishment and analysis of subsequent complete models.Finally,for the situation where the gap change speed cannot be directly measured,a high-gain state observer is designed,which can provide a reference for practical applications.3)In order to verify the rationality of vehicle modeling,track flexible body modeling,control system modeling and the complete modeling of the combination of the three,firstly,the train-track coupling dynamic model is established for the concrete simply supported beam of the main line with relatively simple structure.On this basis,the rigid flexible coupling dynamic model of the train turnout system is established for the turnout with more complex structure.Based on the established train turnout dynamic model,the effects of key design parameters such as vehicle speed,vehicle load,vehicle marshalling,suspension parameters,control parameters,turnout vertical support stiffness and turnout structure damping ratio on the system coupling vibration characteristics are analyzed in detail,revealing the evolution law of dynamic performance of trains and turnouts under the influence of the above factors is discussed,the value ranges of relevant parameters are proposed,and the theoretical design method of dynamic vibration absorption of turnouts is carried out and verified.4)Using the theoretical analysis conclusion,based on the turnout of Shanghai Lingang medium and low speed maglev test base and the maglev vehicle of Tongji University,the line test research on static suspension and dynamic operation of no-load test vehicle is carried out,and the dynamic response characteristics of the coupling system are analyzed in detail in time domain and frequency domain.The test results show that the running stability grade of the vehicle is excellent,and the turnout also has good dynamic performance.Under different operating speed conditions,vehicle body,running mechanism,turnout and control system also show different response characteristics.The vertical dynamic displacement and vertical vibration characteristic frequency of the active beam calculated by the rigid flexible coupling dynamic model of the vehicle turnout system are in good agreement with the measured results,which shows that the model is reliable and applicable.Its conclusions can provide a reference for the optimal design of train and turnout and the improvement of relevant specifications.