Study On Vibration Characteristics Of High-speed Wheel/rail System Considering Wheelset Flexibility

The polygon of wheels will seriously affect the dynamic performance of the vehicle system,especially the high order polygon common in high-speed train wheels,which will cause the medium and high frequency vibration of the vehicle and track system,causing damage to the vehicle and track,and endangering the safety of driving.Based on the rigidflexible coupling system dynamics theory,the dynamic analysis model of the vehicle-track rigid-flexible coupling system was established with ANSYS and SIMPACK software,and the validity of the model was verified by comparing with the measured results.On this basis,the influence of wheel polygon on high-speed wheel/rail system was studied.The main conclusions are as follows:(1)Vibration characteristics analysis of high-speed wheel/rail system considering wheelset flexibility.Based on the vehicle-track rigid-flexible coupling dynamics model,the deflection deformation of axle was analyzed,and the vibration differences between flexible wheelset and rigid wheelset were compared.The results show that: I.Considering the flexibility of wheelset,the deflection of axle increases with an increase of the train speed;II.The vertical acceleration of the flexible wheelset has a high peak value at the rotational vibration frequency,and when the rotational vibration frequency is close to the natural modal frequency of the wheelset,the modal resonance of the wheelset will be excited.III.The flexible deformation of wheelset alleviates the vertical vibration of wheelset to a certain extent,but intensifies the lateral vibration of wheelset.IV.The vertical acceleration of rail increases significantly with the increase of vehicle speed.The higher the speed,the more intense the vibration response of the rail.(2)Influence of wheel polygon on vibration of high-speed wheel/rail system.The polygonal excitation is simulated by harmonic function and applied to the vehicle track rigid flexible coupling model.The influence of 19 ～ 22 order polygonal excitation of high-speed train wheels on the vibration of wheel/rail system is analyzed.The research results show that: I.For the vertical acceleration of wheelset and rail,the change of polygonal order mainly affects its frequency distribution.While the polygonal amplitude mainly affects the acceleration amplitude of the corresponding frequency,it has no effect on the frequency distribution;II.For wheel/rail vertical force,the RMS value will decrease with the increase of polygon order,but the RMS value will also increase with the increase of polygon amplitude.(3)Study on safety limit of High-speed Train Wheels Polygon.Combined with the established model,the influence of polygon wheels on the safety performance of high-speed train operation was analyzed.According to the vertical force limit of wheel/rail,the safety limit of high-order polygon wheels at different speeds was obtained.The research results show that: I.When the driving speed and polygon amplitude remain constant,the change of order has no significant effect on derailment coefficient and wheel load reduction rate for 19-22 polygon wheels common in high-speed railway vehicles.II.When the polygon amplitude increases from 0.06 mm to 0.12 mm,the derailment coefficient and wheel load reduction rate also increase,but they are significantly lower than the limits specified in the Code for Dynamic Performance Evaluation and Test Appraisal of Locomotive and Vehicle.III.Wheel/rail vertical force is most significantly affected by polygon amplitude.By limiting wheel/rail vertical force to 170 k N,it can be obtained that when the driving speed is 250,300,350,400 and 450km/h respectively,the corresponding21-order polygon amplitude limits are 0.053,0.050,0.030,0.025 and 0.020 mm.