Transmission error investigation of gearbox using rigid-flexible coupling dynamic model: Theoretical analysis and experiments

The transmission error (TE) is one of the most important excitations of gearbox vibration. In previous studies, simplified models composed of meshing gears alone were built to analyze the TE. However, the flexibility of other system components was ignored. In this study, a system-level TE investigation of gearbox is carried out by proposing a rigid-flexible coupling dynamic model. In this model, the meshing pair, flexible shaft, and bearing are established by a lumped mass element, beam element, and spring element, respectively. Housing flexibility is introduced into the analysis through model condensation, and a modal test is launched to verify its effectiveness. Moreover, a TE test rig is set up to compare the theoretical and experimental results. These results show that the TE increases with increasing load. Furthermore, the TE decreases when the housing flexibility is considered, especially when the gearbox is running at higher speed and when the housing is a thin-walled structure. Appropriately decreasing the stiffness of the housing can decrease the TE. Additionally, increasing the inner radius of hollow shaft simultaneously reduces the shaft weight and decreases the system TE.