Order-frequency analysis of machine signals. (15th March 2017)

• Record Type: Journal Article
• Authors: Abboud, D.; Antoni, J.
• Is Part Of: Mechanical systems and signal processing. Volume 87:Part A(2017)
• Page Start: 229
• Page End: 258
• Publication Date: 2017-03-15
• Subjects: CS cyclostationary -- SC spectral correlation -- SES squared envelope spectrum -- ACP averaged cyclic periodogram -- CMS cyclic modulation spectrum -- AT-CS angle/time cyclostationary -- OFACP order-frequency averaged cyclic periodogram -- OFCMS order-frequency cyclic modulation spectrum -- OFSCoh order-frequency spectral coherence -- IES improved envelope spectrum -- OFACCoh order-frequency averaged cyclic coherence -- OFCMCoh order-frequency cyclic modulation coherence -- ATCF angle/time covariance function -- TF-IPS time/frequency instantaneous power spectrum -- AF-IPS angle/frequency instantaneous power spectrum -- OLA overlap add -- FBS filterbank summation -- DFT discrete Fourier transform -- FFT Fast Fourier transform; Order-frequency analysis -- Angle/time cyclostationary -- Rotating machines -- Variable speed conditions -- Order-frequency spectral correlation -- Improved envelope spectrum; Structural dynamics -- Periodicals; Vibration -- Periodicals; Constructions -- Dynamique -- Périodiques; Vibration -- Périodiques; Structural dynamics; Vibration; Periodicals; 621
• DOI: 10.1016/j.ymssp.2016.10.024
• Languages: English
• ISSNs: 0888-3270

Abstract

Abstract: Latest researches have asserted the eligibility of angle/time cyclostationarity in analyzing machine signals when operating under variable speed conditions. A core descriptor in this framework is the order-frequency spectral correlation (OFSC), basically estimated by the averaged cyclic periodogram (ACP), being able to jointly decode (i) the angle-dependent modulations related to the machine kinematics and (ii) the time-dependent carriers related to the machine dynamics. The present paper comes into this context with the aim of enriching this framework with new tools excerpted from cyclostationarity. In particular, a new estimator of the OFSC based on the cyclic modulation spectrum (CMS) is proposed and compared with the ACP in terms of resolution, statistical performance and computational cost. In addition, two related tools are theoretically addressed and their estimators are derived through the ACP and CMS. Specifically, the optimality of the "order-frequency spectral coherence" (the normalized/whitened form of the OFSC) in revealing cyclic components according to their SNR is demonstrated. Also, the "improved envelope spectrum" is derived from the latter by integrating over the spectral frequency variable, evidencing considerable enhancement over the squared envelope spectrum. The potentiality of the proposed tools and the adequacy of the related estimators are experimentally investigated on simulated and real-world vibration signals. Highlights: Theoretical investigation of the order-frequency spectral correlation. Proposition of a new estimator based on the cyclic modulation spectrum. Comparison with the averaged cyclic periodogram. Derivation of related tools together with their estimators. Validation on numerical and experimental signals in variable speed.