Dynamic characteristic analysis of a gear-rotor-bearing coupling system considering bearing fit

The fitting relationship between the bearing and the shaft/housing significantly affects the dynamic behavior of the Gear-Rotor-Bearing (GRB) coupling system. Previous works often simplify the bearing as a spring element with constant or time-varying supporting stiffness and ignore the clearance or interference fit between the bearing rings and shaft/housing. In addition, the interactions of the bearing contact characteristics and the gear dynamic mesh behavior are rarely investigated. In this work, a coupled dynamic model of a GRB system is proposed by comprehensively considering the interference fit between the bearing inner ring and shaft, the clearance fit between the bearing outer ring and housing, the interactions of the periodic gear mesh stiffness excitation and the stochastic collisions between the bearing cage and rolling elements. The simulated responses are directly compared to the measured results to validate the proposed model. It was found that an increase in outer ring-housing clearance leads to higher gear mesh force amplitudes and alters the amplitudes of natural frequency related components of the GRB system. Properly adjusting the fit relationship between the bearing and the shaft/housing can directly reduce the internal contact forces of bearings and thereby extend their service life in the GRB system.