Study On Dynamic Characteristics Of Fault Axle Box Bearing Of High Speed Train

In recent years,with the rapid development of China’s high-speed railway and the continuous improvement of train operation speed,higher requirements are put forward on the performance of each train system.As the key component of bogie,the axle box bearings are closely related to the safety and stability of the train.Therefore,it is necessary to carry out real-time monitoring and fault diagnosis for axle box bearing.However,during train operation,it is difficult to observe the dynamic behavior of the internal components of the bearing through the sensor,and most of the bearings are in normal service state,so it is difficult to obtain the fault data of the bearing.In this thesis,through the dynamic simulation,the normal bearing and fault bearing under different working conditions are simulated,and the dynamic characteristics of bearing is studied,which can provide a reference for the diagnosis and prevention of bearing fault and the optimization design of bearing structure.This thesis takes the axle box bearings of high-speed train as the object of study.First,based on Hertz contact theory,the dynamic models of normal bearing,bearing with peeling failure in the outer ring and bearing with peeling failure in the inner ring are established.The simulation results of the revolution speed of the cage,the rotation speed of roller and the characteristic frequency are compared with the theoretical results to verify the accuracy of the model.Secondly,the dynamic simulation of axle box bearings under different working conditions is carried out to study the influence of peeling failure in the outer ring and inner ring on the dynamic characteristics of the bearing.The results show that: when the roller passes through the peeling failure on raceway,the slip velocity between the roller and raceway will change suddenly,and the roller will slip.The collision between the roller and raceway will increase the slip rate of the cage and reduce the stability of the cage.However,when the inner ring fails,the cage stability will be worse.Finally,based on the vehicle system dynamics and Hertz contact theory,considering the contact relationship between the wheelset and the rail,the dynamic models of high-speed train with normal bearing and fault bearing are established.This thesis studies the influence of the faulty inner ring on the dynamic characteristics of the bearing and the vibration acceleration of the axle box.The results show that the contact force,slip velocity and acceleration will increase with the increase of the velocity of the train.When the bearing is normal,with the increase of the velocity of the train,the stability of the cage first deteriorates and then becomes better.When the bearing inner ring fails,the cage will become more and more stable with the increase of the velocity of the train,but the stability of the cage is always worse than normal bearing.When the inner ring fault occurs,the inner ring fault signal can be detected at the position of measure point 1 below the axle box at different speeds.