Abstract: Gearbox play a vital role in railway vehicles, aero engines, and other rotational machinery. Thus its health condition is significant for the reliable operation of such rotational machinery. To pave the way for the feature extraction of gearbox for its health condition, the vibration response of gearbox with defects is mandatory. The existing dynamic models of gearbox are mainly oriented on its individual components. However, in reality, the vibration measured from the gearbox housing usually couples the ones of the rolling bearing rotor (RBR) system, gear meshing and gearbox housing, as well as the effect of the elastohydrodynamic lubrication. Therefore, the dynamic model of individual component cannot reflect the actual vibration behaviour of the gearbox. Thus, a systematic model coupled the dynamic model of the gear mesh, pinion rolling bearing rotor (RBR) system, gear RBR system, the time-varying displacement excitation caused by a localized defect (LOD), and the effect of the elastohydrodynamic lubrication has been established to predict the vibration response of gearbox in this paper. The various excited vibration of the gearbox housing can then be obtained for analysing the vibration behaviour of the gearbox with the bearing LOD. Moreover, the influences of rotating speed and LOD sizes on the vibration characteristics of the gearbox housing. The established dynamic model is validated by the experiments.

Gearbox; Rotor system; Bearing defect; Time-varying; Lubrication oil film