| The main frequency of high-speed railway wheel rail periodic wear(wheel polygon and rail wave wear)is usually higher than 500 Hz,which has significant high-frequency dynamic characteristics.The wheel-rail periodic wear may greatly aggravate the dynamic interaction between the wheel and rail and cause fatigue of key structural components of high-speed trains,making it one of the major hidden dangers threatening the safe operation of high-speed railways.Field investigations show that the formation of wheelrail periodic wear is closely related to the vibration of ballastless track systems under complex service conditions.However,the existing research on wheel-rail periodic wear rarely considers the broadband vibration behavior of ballastless track systems.So the formation mechanism of wheel-rail periodic wear is still unclear and and the control measures are not perfect.In general,the wheel-rail periodic wear has become one of the key technical problems to be solved urgently in the railway transportation field.This thesis relies on the National Natural Science Foundation——High-speed Railway Joint Fund key project “The research on the modal parameter identification of ballastless track structure of high-speed railway and its effect on wheel-rail relationship”and the Major Scientific Research Instrument Development Project of National Natural Science Foundation of China “High-speed railway wheel-rail dynamic contact attitude detection system based on high-precision structured light”.In response to the unresolved wheel-rail periodic wear problem,a vehicle-track coupled dynamic model suitable for wheel-rail broadband vibration analysis has been established.On the basis of clarifying the characteristics of wheel-rail broadband coupling vibration and the cause of the vibration resonance,the influence of the broadband vibration on the wheel-rail periodic wear under complex service conditions is analyzed.Then the formation mechanism of wheel-rail periodic wear is figured out.Finally,the comprehensive control measures are put forward.This can provide a theoretical basis for ensuring the long-term safe operation of high-speed railways in China.The specific research work and results are as follows(1)The analysis model of wheel-rail broadband coupling vibration in the ballastless track section is established,considering the broadband vibration characteristics of the ballastless track system,wave transmission and reflection between multiple wheelsets and the influence of wheelset flexible deformation.An improved fastener mechanical model considering the vibration of the iron pad is proposed.Combined with the field modal test,a refined analysis model of the broadband vibration of ballastless tack system is established,which is verified by the test modal parameters.This ensures the modeling of broadband vibration of ballastless track system;Because the wave transmission and reflection between multiple wheels and rails within the adjacent bogie range between the front and rear vehicles and the flexible deformation of the wheelsets can not be ignored in the wide-frequency range,a vehicle multi-body system model considering the flexibility of the wheel set is further established combined with the floating coordinate system method.And a high-speed vehicle ballastless track system model suitable for the analysis of wheel rail broadband coupling vibration is constructed with the wheel rail contact model as the link.In view of the huge amount of calculation caused by ultra-high degrees of freedom of large-scale system broadband dynamic model,a fast solution method of "slip-cycle window" for vehicle moving on track is proposed based on the existing research.Finally,dynamic measurements under high-speed operation conditions are carried out to verify the established broadband dynamic model.(2)The wideband distribution and transmission characteristics of wheel-rail coupling vibration were studied,and the influence of ballastless track structure parameters,service environment and damage on wheel-rail coupling vibration was analyzed,and the causes of wheel-track coupling resonance were clarified.From the point of view of energy,the comprehensive analysis indexes of wheel-rail coupling vibration response were proposed,including the impact power and the friction power.Combining with the wheel-rail force index,the wideband distribution characteristics of wheel-rail coupling vibration and the wideband transmission characteristics of wheel-rail system-ballastless bed vibration were studied.The effects of structural parameters of the ballastless track(fastener system,ballastless track structure),service environment and damage(moist environment,environmental temperature along the line and ballastless bed damage)on wheel-rail coupling vibration were analyzed.By comparing the wheel-rail coupling vibration differences under single/double/multiple wheelsets,four modes(of two major types)of wheel-track coupling vibration,which lead to the resonance of the wheel-track system,were identified.The cause of the wheel-rail coupling resonance was clarified.(3)The contributions of the modal characteristics of the wheel-rail system and the ballastless track structure to the wheel polygonal wear were explored.The internal mechanism of the frequent occurrence of wheel polygonal wear in ballastless track under hot and humid environment was explained.The formation mechanism of wheel polygonal wear was revealed.An analysis method to measure the growth degree of the wheel polygons with different orders and an improved analysis index were proposed.The relationship between wheel polygon wear and wheel-rail coupled resonance is studied,and the wheel-rail system modes causing wheel polygon wear are identified.The problem of second-order wheel rotation frequency difference between wheel rail coupling resonance solved by traditional model and typical polygon is solved.The influence of structural parameters and service environment of ballastless track on wheel polygon wear was analyzed.The sensitive mode of ballastless track which aggravates the wheel polygonal wear was identified and its discrimination process was given.Finally,the formation mechanism of wheel polygonal wear of EMUs operating on typical railway lines was revealed.(4)The contribution of vibration of the wheel-rail system and ballastless track structure to rail corrugation was explored.And the influence of service environment and damage state of ballastless track on rail corrugation was analyzed.The formation mechanism of rail corrugations was revealed.The analysis method and index of the increase rate of rail corrugation with different wavelenghs were proposed.The correlation between rail corrugation and wheel-rail coupled resonance is studied,and the wheel-rail system modes causing rail corrugation are identified.The influence of structural parameters,service environment and interlayer damage of ballastless track on rail corrugation was analyzed.The sensitive mode of ballastless track bed that aggravates rail corrugation was identified and its discrimination process was given.Finally,the formation mechanism of rail corrugation on typical railway lines was revealed.(5)The interaction law of wheel polygon and rail corrugation is clarified,and the control measures of wheel-rail periodic wear were proposed and the control effect was analyzed.The wheel-rail dynamic response and wear characteristics under the interaction of wheel polygon and rail corrugation are clarified.The control measures of wheel-rail periodic wear were proposed from two aspects: improving the vibration of ballastless track system(by optimizing the parameters of fastener system,improving the vibration characteristics of ballastless track,and optimize the selection of ballastless track);reducing the wheel-rail excitation conditions(via avoiding the accumulation of wear at the same wavelength,strengthening the condition-based maintenance of wheels under hygrothermal environment conditions,and controlling the residual irregularity of rail grinding).And their control effects are analyzed. |
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