Prediction of Gear-Mesh-Induced High-Frequency Vibration Spectra in Geared Power Trains

Abstract : Characteristics of vibration spectra induced by gear meshes in both single gear reductions and planetary gear reductions were investigated. Methods were developed to analyze the planet-pass induced vibrations which exist in normal planetary gear reduction systems. It was found that the planet-pass vibration sideband frequencies occur both below and above the base signal at integer multiples of planet-pass frequency and that the sideband amplitudes may exceed that of the base signal. The effect of planet pair phasing on the vibration sideband spectra was determined for the CH-47 helicopter forward rotor drive transmission first-stage planetary reduction. A computer-implemented analysis was established for predicting vibration sidebands produced by variations in centerline distance, tooth transmitted force, and tooth support discontinuities for single gear mesh systems.