Vibration-modelling-based fault feature analysis for incipient damage identification of sun gear

Abstract Different types of incipient damage to gears need to be distinguished for the reliable and safe operation of mechanical equipment. However, the identification of various types of incipient gear damage is still a challenge for the fault diagnosis of planetary gearboxes. To identify the various types of incipient damage in a sun gear, fault feature analysis is conducted for various damage conditions in a planetary gearbox. First, the internal excitation aroused by gear damage is computed and the effects of the typical damage modes of a sun gear on the internal excitation are demonstrated. Then, the internal excitation of the damaged sun gear is applied into the dynamic model of the planetary gear train to simulate distributed damage or local damage. After that, with the vibration responses obtained from the dynamic model, a vibration signal model is proposed to simulate the vibration signals of the planetary gearbox. Furthermore, the vibration signals are analysed over the time domain and frequency domain. The fault features of the planetary gearbox are characterized by using residual signals and variational mode decomposition signals, which are useful for identifying the various incipient damage types of a sun gear. Finally, the simulated results are validated by experimental tests.