Study on dynamic characteristics of urban rail transit vehicle considering faulty axle-box bearings under variable speeds

Abstract

Axle-box bearing is the key component of urban rail transit vehicles, and its performance status seriously affects the operation safety and stability of the train. Therefore, analyzing the dynamic response of a vehicle system by considering axle-box bearings is the premise of ensuring its safety. Besides, vehicles generally run under the condition of variable speeds, which leads to more complex dynamic response for the vehicle system. Accordingly, studying the influence of faulty axle-box bearings on the vehicle system under variable speeds can reflect the running situation of trains more realistically. In this paper, a dynamics model of axle-box bearings is considered in the vehicle-track coupling model, and the dynamic response of the vehicle system with faulty bearings under variable speeds is analyzed. Firstly, a vehicle-track coupling dynamics model considering axle-box bearings is established, which considers the coupling effect between axle-box bearings and other vehicle components. The bearing inner race is fixedly connected with the axle shaft, and the bearing outer race is fixedly connected with the axle-box housing. Then, an outer race defect model and an inner race defect model of axle-box bearings are respectively established to simulate the internal fault excitation which is often generated in the running process of train bearings. Finally, considering faulty axle-box bearings and variable speeds, the dynamic response of the vehicle system is simulated by the proposed model, whose effectiveness is validated through the theoretical analysis and field tests. The test results show that the axle-box bearing with an outer or inner race defect has a certain influence on the dynamic response of the vehicle system under variable speeds.