Application of the wavelet transform to health monitoring and evaluation of dynamic characteristics in gear sets

Abstract

This paper deals with health monitoring and evaluation of dynamic characteristics in gear sets. The wavelet transform (WT) is the method used for the time-frequency analysis. The dynamic characteristics of both steel and sintered gears were measured using a power circulating gear testing machine and were analysed in the time-frequency domain using continuous and discrete WTs. Furthermore, health monitoring of gear sets was carried out and tooth surface failure by pitting was diagnosed using WTs. The vibration acceleration characteristics of the gearbox could be divided into two different behaviours above and below the tooth mesh frequency. A failed tooth could be found by a change in WT intensity of the vibration acceleration, taking the tooth meshing into consideration. Since the discrete WT is able to provide the signal with the component of tooth mesh frequency, it was found to be superior to the continuous WT. In the case of failure at the dedendum surface of a driven gear, the amplitude of the vibration acceleration with the component of tooth mesh frequency became larger as after meshing of the failed tooth. Therefore, not only the vibration of the gear sets but also the condition of tooth meshing would have to be taken into consideration to diagnose failed teeth.