Establishment And Dynamic Response Analysis On Force-thermal Coupling Model For Axle Box Bearing Of High-speed Train

In recent years,China’s high-speed railway has made remarkable achievements,with its operating mileage and passenger capacity ranking first in the world.However,in the face of large-scale train operation,its security issues are also increasingly concerned.The axle box bearing wheel set rotor system is one of the key components of the bogie system,and its motion state is directly related to the safe and stable operation of the train and the personal safety of passengers.Therefore,the fault mechanism and evolution law of axle box bearings have become the focus of many experts and scholars.In this paper,the force thermal coupling model of axle box bearing is established by comprehensively considering the influence of multiple factors such as force,bearing lubrication and temperature characteristics,and a series of research and analysis work is carried out on its vibration characteristics and temperature characteristics.The main research contents of the paper include:(1)The dynamic model of high-speed train bearing rotor system under variable speed condition is established,and the spatial angular position of the rolling element in any time period is determined by angle iteration method.The outer ring fault,inner ring fault and rolling element fault are respectively added in the model,and the order spectrum of the system vibration response is analyzed.Corresponding experimental verification is carried out,and the results show that the model simulation results are consistent with the experimental results,which verifies the effectiveness of the model.(2)Under the variable speed conditions,the system stability with different fault types of the bearing is qualitatively analyzed by using the axis trajectory.Then the system stability under the conditions of different angular accelerations and different fault types is quantitatively evaluated by using two-dimensional moment invariants.The comprehensive analysis results show that the rolling element fault has the greatest impact on the system stability;The critical state of system stability is studied under different bearing fault types,and the maximum fault size corresponding to different speeds is determined,respectively.(3)The steady-state and transient temperature field models for the bearing rotor system of high-speed train are established by using the thermal network method.The effects of ambient temperature,bearing angular speed,vertical load on the bearing,bearing fault size and type on the node temperature of the system and its changes are analyzed respectively.The analysis results show that the worse the condition of the system,the higher the node temperature and the faster the change.The effectiveness of the two models is verified by the comparison between the actual line data on the train and the simulation results.(4)The mechanical thermal coupling model for bearing rotor system of high-speed train is established,and the importance of lubrication is explained in the simulation analysis.The vibration and temperature characteristics of the coupled model are respectively verified by two experiments,and the simulation results are in good agreement with the experimental results;Based on the coupling model,the influence of track irregularity on system characteristics is studied,and the causes of bearing faults under different working conditions are explained from the perspective of mechanism,and the corresponding solutions are put forward.Through the establishment and simulation analysis of the dynamic model for the bearing rotor system of high-speed trains,the paper proposes a quantitative evaluation system for the stability of the system movement based on two-dimensional constant moments.The proposed force thermal coupling model is used to study the impact of track irregularities,reveal the mechanism of bearing failures under extreme working conditions,and study the changing laws of the lubrication state,temperature characteristics and vibration response.The research contents and conclusions of this paper have certain engineering application value and theoretical guidance significance for guiding the design,operation and maintenance of axle box bearings and developing rotor dynamics methods.