Demodulated time-direction synchrosqueezing transform and its applications in mechanical fault diagnosis

• Published in: Journal of vibration and control 2023-09, Vol.29 (17-18), p.3880-3892
• Main Authors: Li, Xiaolu, Xiao, Baosen, Guo, MingAng, Liu, Baolin, Xia, Jingbo, Tu, Xiaotong
• Format: Article
• Language: English
• Subjects: Experimental research; Fault diagnosis; Frequency analysis; Frequency variation; Time-frequency analysis
• ISSN: 1077-5463; 1741-2986
• DOI: 10.1177/10775463221106524

Time-frequency analysis is recognized as a dynamic tool to analyze the nonstationary signal. The synchrosqueezing transform is usually applied as a post-processing method to further improve the readability of the time-frequency representation. Synchrosqueezing transform is related to the reassignment method and can be performed in two directions, namely time direction and frequency direction. Frequency-direction reassignment helps to squeeze the slowly changing ridge. However, the time-direction reassignment is efficient to process the signal with rapid variation in instantaneous frequency. Thus, there exists a conflict in most of the time-frequency analysis methods while dealing with a signal containing both of these two components. In this study, a new method called demodulated time-direction synchrosqueezing transform is introduced, which is not only capable of achieving a higher compact TFR but also allow reconstructing the mode. In order to explain demodulated time-direction synchrosqueezing transform, a signal model is established in frequency domain. Then, a demodulated procedure is implemented to eliminate time-frequency analysis diffusion. Finally, time-direction reassignment is carried out to further enhance the energy concentration of the time-frequency analysis. The proposed demodulated time-direction synchrosqueezing transform method is evaluated by both simulation and experimental research. The results reveal that the performance of demodulated time-direction synchrosqueezing transform is better than the conventional time-frequency analysis methods, and it can be applied to the fault diagnosis in a machine.