A Novel Strategy for Signal Denoising Using Two-Layer SVD and its Application to Rub-impact Fault Diagnosis of Aero-engine

The rub-impact fault, which occur in the aero-engine, can cause the frequency modulation (FM) in its vibration signal. Oscillated instantaneous frequency (IF) is a phenomenon of such kind of modulation mode, which carry critical fault information of aero-engine. In this paper, by using bandpass filter, which allow IX and 3X to pass respectively, vibration signal can be divided into two signal components. Two-layer Singular value decomposition (SVD) is utilized to reduce signal noise of each signal component and instantaneous frequency of each signal component. The intrawave FM feature of the signal are presented through the HT analysis. The proposed method is validated with numerical simulation and then demonstrated on aero-engine data with rub-impact fault. The proposed method is proper for the analysis of modulated signals and is a valid tool for detecting rub-impact faults of aero-engine.