SENSITIVITY OF PLANETARY GEAR NATURAL FREQUENCIES AND VIBRATION MODES TO MODEL PARAMETERS

The natural frequency and vibration mode sensitivities to system parameters are rigorously investigated for both tuned (cyclically symmetric) and mistuned planetary gears. Parameters under consideration include support and mesh stiffnesses, component masses, and moments of inertia. Using the well-defined vibration mode properties of tuned planetary gears, the eigensensitivities are calculated and expressed in simple, exact formulae. These formulae connect natural frequency sensitivity with the modal strain or kinetic energy and provide efficient means to determine the sensitivity to all stiffness and inertia parameters by inspection of the modal energy distribution. The natural frequency sensitivity to operating speed is calculated to estimate the impact of gyroscopic effects. While the terminology of planetary gears is used throughout, the results apply for general epicyclic gears.