Dynamic response of the axle-box bearing of a high-speed train excited by wheel flat

Axle-box bearings are directly affected by wheel–rail impacts as fixedly connected to wheelset. As an inevitable wheel-failure, wheel flat can cause severe wheel-rail impact, which may deteriorate the performance of axle-box bearings, even threatening train running safety. To investigate the dynamic response of axle-box bearings excited by wheel flat, two rigid-flexible coupled vehicle dynamics models of motor and trailer cars are developed. The axle-box bearing, flexible axle-box and wheelset are thoroughly established in trailer car model. The gear transmission system and flexible gearbox are further integrated into motor car model relative to trailer model. The accuracies of models are verified by the field-test results. The dynamic responses of axle-box bearings excited by wheel flat are analyzed. Results indicate that the vibration and dynamic forces acting on axle-box bearing augment with the increasing of flat length. The vibrations intensify gradually from wheelset, inner ring, and outer ring to axle-box, particularly increasing significantly with long flat lengths. Moreover, the dynamic forces within axle-box bearing first increase before decreasing with the growing operating speed. Being structurally difference, wheel flat exerts more significant effects on the axial and radial forces within the bearings of motor car than those of trailer car.