Investigating Vibration Properties of a Planetary Gear Set with a Cracked Tooth in a Planet Gear

Comparing with fixed shaft gearbox, vibration properties of planetary gearbox are much more complicated. In a planetary gearbox, there are multiple vibration sources as several pairs of sun-planet gears and several pairs of ringplanet gears mesh simultaneously. In addition, the signal transmission path changes due to the rotation of the carrier. To facilitate fault detection of a planetary gearbox and avoid catastrophic consequences caused by gear failures, it is essential to understand the vibration properties of a planetary gearbox. This paper aims to simulate vibration signals and investigate vibration properties of a planetary gear set when there is a cracked tooth in a planet gear. Displacement signals of the sun gear and the planet gear, and resultant acceleration signals of the whole planetary gear set will be simulated and investigated. Previous work mainly focuses on the vibration properties of a single component, like the sun gear, the planet gear or the carrier. This paper simulated the vibration signal of a whole planetary gear set when there is a cracked tooth in a planet gear. In addition, fault symptoms will be revealed, which can be utilized to detect the crack in the planet gear. Finally, the proposed approach is experimentally validated.