| High-temperature superconducting(HTS)maglev trains have become one of the development trends and research priorities in the field of advanced rail transportation because of their unique advantages such as frictionless and low noise.At this stage,HTS maglev trains are being developed out of the laboratory for engineering applications.In the process of engineering applications,it is crucial to simulate the actual operating environment and operating conditions and analyze the dynamics of the vehicle in actual operation.Establishing an accurate coupled vehicle-Permanent magnet track(PMT)-flexible bridge dynamics model is the key to study the dynamics of the vehicle during actual operation.This paper takes the opportunity of HTS maglev train towards engineering application,establishes a more accurate coupled system dynamics model,and studies the vehicle operation vertical dynamics characteristics,mainly with the following contents and conclusions.(1)The"truncated beam"method is introduced into the HTS maglev coupling system to establish a three-dimensional truncated beam model of the PMT,and the truncated beam model is solved using the modal superposition method.This model has the advantages of less degrees of freedom,accurate calculation and high efficiency compared with the traditional modeling method of long track.(2)Dynamics model of HTS maglev vehicle system based on multi-body dynamics theory.The vehicle system contains the vehicle body,6 suspension frames and 72 engineering dewars,and the structural parameters of each part of the model are determined according to the engineering vehicle design parameters.This model was solved by a MATLAB program.(3)Considering the PMT irregularity excitation,the suspension height of the engineered dewar is stabilized in the range of 8～14 mm when the vehicle runs at 300 km/h to reach the stable running condition.The PMT exhibits a low response to external excitation and easily suppressed vibrations because of its own structure and the’magnetic-track relationship’characteristic of HTS maglev vehicles.The influence of different PMT support spacing on the coupling system is calculated,and the elastic support spacing under the PMT is suggested to be 1 m after considering the factors of driving safety and construction cost.The different vehicle operating speeds have less impact on the system response and the system maintains a very stable operation.(4)Establishment of HTS maglev vehicle/track/bridge coupling system.The analysis results show that the vehicle system in the’foundation section’driving to the’bridge section’,the vehicle system of the corresponding sudden increase,but the overall vehicle body vertical acceleration are maintained in the range of 0.02m/s~2,while the maximum vertical displacement of the bridge span also meet the specification requirements.The study analyzed the impact of different bridge spans on the system,and recommended the use of a flexible bridge with a span of 25 m,taking into account various factors such as cost and safety and stability of vehicle operation.The effect of different secondary suspension parameters on vehicle performance is investigated.The secondary suspension stiffness increases from 0.1MN/m to 0.5 MN/m,and the vertical motion Sperling index of the vehicle body increases from1.9828 to 2.5791.In actual engineering vehicles,secondary suspension structure with less vertical stiffness can be chosen.In this paper,the vertical vibration characteristics of the coupled HTS maglev vehicle/track/bridge system are investigated.The vibration response of the coupled system when the maglev vehicle runs on a flexible PMT and the vibration behavior of the vehicle/track/bridge when the vehicle crosses a bridge are analyzed.The effects of structural parameter variations on the vibration response of the coupled system are analyzed to provide design reference values for the engineering application of HTS maglev. |
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