| As an important way to effectively solve the urban traffic congestion,realize the reasonable layout of urban space and ensure the comprehensive sustainable development of the city,Urban rail transit is in an important period of rapid and integrated development now.Among them,the suspended monorail vehicle system is expected to have a broad development and application prospects in China,which acts as a diversified urban rail transit system with lots of advantages.The operation process of the suspended monorail vehicle is a complex dynamic process.As one of the important vibration reduction devices for the vehicle system,the dynamic parameters and the design of structure form for the secondary suspension system is directly related to the stability and ride comfort of vehicle.The selection of dynamic parameters and the design of structural form are directly related to the ride comfort of vehicles and the riding comfort of passengers.Therefroe the research on the dynamic modelling and the analysis of vibration characteristics for the suspended monorail vehicle has important theoretical guiding significance and engineering application value for the further optimization design of the key technology of the suspended monorail vehicle in China.Firstly,the structural characteristics and technical characteristics of the suspended monorail vehicle system are introduced,and the development history and research status of the vehicle system are summarized.The train marshaling modes,technical parameters and structural characteristics of two typical suspended monorail vehicle system with symmetrical suspension,rubber tire and the box girder in Japan and Germany are taken as the emphatically elaborated.Based on the multi-body dynamics theory,a detailed dynamic model of the suspended monorail vehicle with 52 degrees of freedom is established,considering the nonlinear characteristics of the tire and stop.Combined with the results of field dynamics test of the suspended monorail vehicle,the measured and simulated results for the vertical and lateral acceleration of car body are compared and analyzed in time and frequency domain.The comparison results show that the simulated results are in good agreement with the measured results,and the validity of the simulation model is well verified,of which can be used for further research and analysis.The influences of suspension parameters such as vertical stiffness,vertical damping and lateral stiffness for the secondary suspension system on vehicle vibration characteristics under different load conditions are analyzed based on the simulation model.The following conclusions can be drawn that,with the calculation parameters concerned in this paper,the optimal vertical secondary suspension stiffness and the vertical damping is about 0.2~0.3 MN/m and 8~10 kN?s/m,respectively.The lateral stability of vehicle is optimal with the lateral stiffness of 3~4 MN/m.The lateral acceleration and stability of the car body increases with the increase of the transverse span of the bottom for the crane beam,while the lateral displacement of the car body decreases with the increase of the transverse span.Based on the Quasi-Zero-Stiffness(QZS)theory,the application of the new vibration isolation technology in the vibration characteristics for the suspended monorail vehicle is analyzed.The QZS characteristics of the secondary suspension system is realized by using two parallel oblique springs with the existing vertical elastic elements,combined with the structural characteristics of the bogie.The vibration isolation characteristics of secondary suspension system with QZS system and traditional linear stiffness system are further studied adopting the dynamic model with the co-simulation of UM and Matlab/Simulink.The following conclusions can be drawn that the vertical dynamic response of the vehicle with QZS system is obviously lower than that of the traditional linear stiffness system in time domain,and the low frequency vibration isolation is satisfactory in the frequency domain. |
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