Detecting the 3D spatial varying crack evolution-induced vibration of gearbox through a system level rigid-flexible coupling model

Abstract

Gear crack evolution is a complex process; therefore, fault diagnosis and monitoring can help to avoid catastrophic accidents. In view of the deficiency that the simple linear plane assumption is made in the conventional crack model, the 3D spatial varying crack evolution (propagating in the depth, tooth width and tooth profile directions simultaneously) is investigated based on the linear elastic fracture mechanics in this study. The acquired crack morphology is used to analyse the time-varying meshing stiffness variation. Then, a system level rigid-flexible coupling model consisting of a housing, gear, shaft, and bearing is utilized to predict the dynamic response, and the theoretical results are compared with the experimental results. Furthermore, crack evolution-induced vibration detection is carried out by the proposed model, and the frequency spectrum characteristic, statistical indicator and instantaneous energy are obtained. The results reveal that the vibration impact is less obvious at the initial stage of crack evolution, but the instantaneous energy can amplify and capture the fault feature. Decreasing the housing stiffness can decrease the vibration impact induced by crack evolution; nevertheless, it increases the difficulty of crack detection.