Modal parameter estimate of time-varying system using operational modal analysis based on hilbert transform

In this paper an approach for the identification of the modal properties of a time-varying system in the Operational Modal Analysis (OMA) framework is presented. The natural frequencies are estimated using the Hilbert-Huang Transform Method (HHTM) for its capabilities to track the time variations of such modal properties. Then, the Hilbert Transform Method (HTM) is applied for estimating both the damping ratios and mode shapes, not available from the previous method. The developed approach has been numerically assessed considering an aeroelastic system. The accuracy in time-tracking the modal parameters has been investigated by analyzing the numerically simulated time responses from a panel flutter model subjected to random operating loading for which the analytical solution is available.