Vibration Characteristics And Experimental Study Of Axle Box System Of High Speed Train

China’s high-speed railways have the characteristics of wide geographical area,complicated operation routes and large changes in operating climate,thus with the continuing increase of highest operating speed of high-speed EMUs in China,the safety and stability of train operation are facing more severely test and higher requirements.In the operating process of the high-speed train,the axle box bearing is subjected to the excitation generated by the contact between the wheel and rail,the dynamic force generated by the vibration of the vehicle body and the frame,the meshing excitation of the gear pair during the power transmission process,and the dynamic load caused by the bearing itself.Bearings alone or in combination with these loads will cause fatigue damage and shortened service life of axle box bearings.The length of axle box bearing’s fatigue life will directly affect the operational safety of high-speed trains.Therefore,this thesis focuses on the dynamic characteristics of axle box bearings in the service process,using numerical simulation and line test to study the vibration characteristics and load characteristics of high-speed train axle box bearings.The research content mainly covers the following aspects:(1)Aiming at the source of vibration excitation of vehicle-rail system,the coupling relationship of interaction force of "vehicle-orbit" system is analyzed.At the same time,the vehicle-track coupling dynamic model is built according to high-speed vehicle and slab ballastless track structure.The vibration differential equations of each rigid body and rail of the vehicle system are analyzed.The calculation method and formula of the vertical force of the wheel-rail contact are analyzed by the wheel-rail contact model.The rigid-flexible hybrid model of the bogie is established.With the help of this model,the mathematical model of the bogie one-line suspension system,the secondary suspension system,the overall suspension system and the equivalent mathematical model of the overall suspension system are established.The vibration differential equations and dynamic stiffness calculation methods of the bogie one-line suspension system,the secondary suspension system and the integral suspension system are obtained through analysis.(2)The source of vibration excitation load of axle box and axle box bearing is analyzed;at the same time,the characteristics of vibration excitation load are analyzed.The mechanism produced by dynamic excitation of axle box bearing is analyzed.The fault model of axle box bearing is established and the variation of bearing clearance caused by surface defects of different bearing components is analyzed.(3)The structural characteristics of the motor train bogie and the trailer bogie are introduced.With the help of multi-body dynamics simulation software,the motor train model with the transmission system and the trailer model without the transmission system are established.The transmission system model considers the time-varying characteristics of the gear mesh stiffness and the influence of transmission error,besides,the influence of the gear transmission system on the lateral vibration and vertical vibration of the axle box bearing is analyzed through the motor vehicle model and the trailer model.The type of wheel tread damage is introduced,and the wheel-to-bend model is established.The influence of different flat lengths on the vibration performance of axle box bearings at different speeds is analyzed through the simulation analysis.The wheel polygon model is established and the effects of different multi-deformation parameters on the vibration characteristics of axle box bearings are simulated by different wheel polygon parameters.The force of the tapered roller bearing is analyzed,and different bearing fault models are established.The vibration characteristics of the axle box under different bearing faults are analyzed.Under the same speed and defect size,the bearing outer ring defect has the greatest influence on the axle box vibration,and the bearing roller defect has the least influence on the axle box vibration.The bearing roller defect has the least influence on the vibration of the axle box.For bearing outer ring defect,characteristic peaks appear at the frequency doubled of the fault frequency.For bearing inner ring defect and roller defect,not only the characteristic peaks appear at the frequency doubled of the fault frequency,but also the modulation sideband.(4)According to the structural form of the axle box bearing,the design scheme for the axle box bearing test is proposed.The vibration performance index of the test bench is analyzed according to the measured vibration acceleration data of the axle box.Based on the track irregularity and the ultra-high line information,the displacement index of the test bench is analyzed,and the function and structure of the test bench were introduced and analyzed.On the basis of the vibration frequency of the axle box bearing,the test bench is divided into two types:high-frequency test bench and low-frequency test bench.The low-frequency test bench is driven by six hydraulic actuators.It is used for the model of low-frequency vibration of the bearing,the simulation of track irregularity spectrum,and can also be used for the analyze of the strength of the vibration platform;the high-frequency test bench is driven by the electromagnetic vibration exciter and it is mainly used for the simulation of the high-frequency vibration environment of the bearing.On the basis of the structure of the test bench,the test position and gesture driving spectrum solving model is established,and the track irregularity simulation test position and gesture measurement method is analyzed.According to the corresponding position and gesture of the test bench,the displacement command of each actuator is pushed out;the solution process in the position and gesture measurement process is analyzed.By simulating test the different types of orbital irregularities,the error of the simulated orbital irregularity spectrum of the test bench is analyzed,and the effectiveness of the solution model and position and gesture measurement method is verified.(5)Based on the actual test data of the line,the vibration characteristics of the axle box bearing during actual operation are analyzed.The effects of different speeds of uniform speed on the vibration of the axle box are analyzed.The vibration characteristics of the axle box under acceleration and deceleration conditions are analyzed according to wavelet time-frequency analysis theory.The load spectrum of the axle box during service is analyzed by the rain flow cycle counting method.The vibration spectrum of the axle box bearing test based on multi-sample fusion is established according to the load data of different operating conditions.According to the nuclear density rain flow extrapolation method,the fatigue acceleration load spectrum of the axle box bearing is obtained,and the 8-level load block spectrum of the axle box bearing is compiled.The stress analysis of the axle box body under the operating load condition is carried out.According to the situation of stress distribution,the patch position of the strain gauge is determined.Based on the measured axle box stress data,the fatigue life of the axle box is analyzed.