Cyclomap: A new phase-cycle analysis to study the kinematics of gears and bearings

Abstract

The object of this paper is to propose a new phase-cycle analysis for gear and bearing diagnostics of rotating machinery which synthesises the theory of angle-time cyclostationary (AT-CS). The motivation for this research came from bearing diagnostics which is confronted by the inevitable smearing phenomenon due to bearing slip. The bearing signal under non-stationary conditions is neither jointly second-order cyclostationary (CS2) nor pseudo-cyclostationary (pseudo-CS) and, hence, most CS2 tools are subjected to loss of diagnostics information. The proposed phase-cycle analysis is believed to propound the study of the kinematics of gears and bearings, and it will significantly modify the prevailing historical interpretation of the bearing slip. In this paper, the phase-cycle analysis which is based on the theory of AT-CS is named the “cyclomap” because it can provide much more information about the kinematics of cyclostationary and cyclo-non-stationary signals. The cyclomap shows some interesting features in delineating the energy distribution of the kinematical properties of machines at an angular period of interest. In order to further study the properties of the cyclomap, it is systematically compared to the well-known order-frequency cyclic modulation coherence in diagnosing the CS2, pseudo-CS, and second-order cyclo-non-stationary signals of the experimental datasets.