Analysis of Gearbox Compound Fault Vibration Signal Using Morphological Component Analysis

Abstract

Based on the improvement of coefficient threshold denoising method, the morphological component analysis(MCA) is applied to the vibration signal of a gearbox with compound fault. When a gear in a gearbox is locally damaged, the amplitude-modulation and frequency-modulation(AM-FM) component always appear in the vibration signal, and when a rolling bearing is locally damaged, the periodic transient impulse component arises in the vibration signal. The amplitude of AM-FM component varies relatively slower and thus can be considered as the smooth part of the vibration signal, while the amplitude of the impulse component changes relatively rapider and thus can be considered as the detail part, therefore, according to the morphological difference, both components can be separated. By using MCA, the vibration signal of a gearbox with compound fault can be decomposed into the impulse component containing the fault information of rolling bearing, the harmonic component containing the fault information of gear and the residual component, and then the compound fault diagnosis of rolling bearing and gear can be carried out according to the envelope spectra of the impulse component and harmonic component respectively. The results, obtained by the analysis of the vibration signals of gearbox with compound fault, indicate that the proposed method can effectively separate the fault characteristics of rolling bearing and gear, and it is superior to empirical mode decomposition(EMD) for fault feature extraction.