Planetary Gear Modal Vibration Properties Torque Sensitivity

The effect of preload torque on planetary gear behavior is investigated with experiments and mathematical models. Natural frequencies, mode shapes, and damping are influenced by mean torque levels. Natural frequencies increase with greater torque. Damping increases in some modes and decreases in others. The mode shapes undergo various changes as torque increases as demonstrated in the trajectory of a planet gear in a high frequency mode. A finite element bearing model is used to obtain the load dependent stiffness of the planet bearings, and these values greatly increase the accuracy of a lumped parameter model in predicting the natural frequencies measured in experiments.