Understanding vibration properties of a planetary gear set for fault detection

This paper investigates the vibration properties of a planetary gear set. A two-dimensional lumped mass model is developed to simulate the vibration signals of a planetary gear set in the perfect and crack situations. Through dynamic simulation, the vibration signals of each individual component can be simulated, including the vibration signals of the sun gear, each planet gear, and the ring gear. By incorporating the effect of transmission path, resultant vibration signals of the gearbox at the transducer location are obtained. Results show obvious fault symptoms in the signals of an individual component, such as the sun gear. After going through the transmission path, amplitude modulation is shown in the resultant vibration signals. When there is a crack on a sun gear tooth, a large amount of sidebands appears in the vibration spectrum. The locations of these sidebands are investigated and identified, which are helpful for fault detection.