Acoustic intensity technique applied to monitor planetary gears

Abstract

Condition monitoring of gear trains by classic techniques based on vibrations and/or extensometry measurements requires the preparation of the sensor contact surfaces and the cables installation. In the case of planetary gear trains, this task is more difficult due to their compactness and the complexity of the relative movements among their different elements. As an alternative, the authors studied the possibility of using acoustic measurements for the planetary gear-set characterisation, as well as for predictive maintenance of this mechanical system. In order to perform this study, a suitable measurement equipment was selected and a bespoke software was developed to control it, to process the data, as well as to represent the results. This informatic tool was used to perform the acoustic characterisation, in which acoustic pressure and intensity measurements were combined with advanced algorithms, such as sincronous-average technique. In this study, two different failures were experimentally recreated in a commercial gearbox, representing the results by frequency and order spectra and intensity maps. The obtained results were compared with those obtained in the box without defect.