Synchroabsorbing Transform With Application to Fault Diagnosis of Aerospace Engines

Abstract

Time–frequency analysis (TFA) methods are significant in vibration signal analysis and fault diagnosis of mechanical equipment. The existing TFA methods mainly focus on the accuracy of instantaneous frequency (IF) and acquire highly refined time–frequency (TF) ridges. However, in engineering applications, the amplitude of a specific mode in the signal is equally important to the IF, the varying trend of which reflects the working condition of the machinery equipment. The accuracy of amplitude has not received enough attention in current research. In this article, a novel TFA postprocessing method named “synchroabsorbing transform (SAT)” is proposed. This method first calculates the TF ridge based on the short-time Fourier transform (STFT), then the range of each mode is determined by detecting local minimum values in the amplitude spectrum, and the TF ridges actively absorb the TF coefficients within the range. The simulation and engineering examples indicated that this method can maintain the accuracy of IF and express the amplitude of signals more accurately in TF representation, which is significant in machinery vibration signal analysis.