Experimental measurement of the effects of torque on the dynamic behavior and system parameters of planetary gears

Experiments designed to capture the independent motion of spur planetary gear components show the influence of mean operating torque on system parameters and dynamic response. All natural frequencies increase with higher torque, but the natural frequencies of modes with significant planet bearing deflection are particularly sensitive to torque. Current lumped-parameter models do not consider the anisotropic nature of planet bearing stiffnesses, but this research shows that the accuracy of these models is increased when the radial and tangential planet bearing stiffness components are calculated separately. These bearing stiffnesses depend on the mean bearing forces in the two directions. A finite element/contact mechanics model provides accurate calculation of the anisotropic, load-dependent planet bearing stiffnesses and the load-dependent mesh stiffnesses. An analytical model using these values accurately predicts changes in the experimentally measured natural frequencies of modes with high strain energy in the planet bearings for varying mean torque. Experiments also show changes in the mode shapes and damping ratios with changing torque.