Nonlinear Dynamic Behavior Analysis Of Axle Box Bearing Rotor System For High Speed Train

In recent years,China's high-speed railway business is booming.Once the axle box bearing,key part of high-speed train is out of order,the running state of high-speed train will be changed directly,which easily leads to the serious accident.The bearing with failure will show complex nonlinear dynamic behavior during operation.The essential laws hidden in the system,the mechanism of failure generation and the law of evolution will be found easily by establishing the nonlinear dynamic model of high-speed train axle box bearing rotor system and using the nonlinear theory to study the motion state of the system,which provides the theoretical basis for the design,overhauling and maintenance of axle box bearing of high speed EMU.Firstly,the vibration mechanism of the bearing is analyzed,the practical fault types and causes of the rolling bearing is introduced and classical fault characteristic frequency formula of the bearing are given.Also the basic idea of the numerical solution of the system is introduced by Runge-Kutta method,the basic concepts of bifurcation and chaos are explained in detail,and the basic method of analyzing the motion state of the system by using bifurcation and chaos theory is explained in detail.Secondly,a nonlinear dynamic model of axle box bearing rotor system in EMUs with outer ring faults is built,and three nonlinear factors were considered,such as clearance of bearing,nonlinear Hertzian contact force between balls and races,and unbalance force because of the rotor eccentric mass.The validity of the model is verified by the experiments.The vibration response of the system is obtained by the numerical solution of the system.The influence of bearing inner ring speed and fault size on system response is analyzed,and toroidal rupture,doubling bifurcation and paroxysmal path to chaos motion are found.Lastly,the change trend of system response with the fault dimension and other parameters is deeply analyzed.The characteristics of the system are analyzed by two statistics of kurtosis and information entropy.The result show that two statistics of kurtosis and information entropy have corresponding relationship with the change trend of fault size,which validates the correctness of the model from one aspect,on the other hand,it is also found that there is a complex nonlinear correspondence between the kurtosis value of the bearing outer ring vibration displacement and the bearing fault size,that is analyzed in two cases,which are fixed speed and different relational speed.Finally,the results are verified by the experiment.The dynamic analysis results of the bearing rotor system are of certain value for studying the mechanism and evolution of the bearing failure of the axle box.It can provide theoretical guidance to the actual maintenance of bearing.The statistical characteristic analysis of the bearing outer ring vibration response provides a new judgement basis for the fault diagnosis,and provides a new train of thought for developing the fault diagnosis algorithm.