Regularized time-varying operational modal analysis illustrated on a wind tunnel testing measurement

This paper presents an efficient nonparametric time-varying (TV) system identification method for the Operational Modal Analysis (OMA) framework. OMA tackles industrial measurements of vibrating structures in real-life operating conditions without the exact knowledge of the excitation signal. The main issue is that the dynamics of underlying systems may vary significantly when operating in real-life conditions. In this case it is desired to carefully verify and track the vibration behavior, since during flutter appearance, system destruction can occur. In this work the first results of a regularized time domain based TV OMA method are presented to estimate the linear TV output autocorrelation function of the observed system. The method is illustrated on the measurement of wind tunnel test of an airplane model. Using the proposed methodology, the estimated TV 2D output autocorrelation model provides a good data-fit with respect to tracking of varying resonances.