TRACKING THE MODAL PARAMETERS OF TIME-VARYING STRUCTURES BY REGULARIZED NONPARAMETRIC ESTIMATION AND OPERATIONAL MODAL ANALYSIS

This paper presents an efficient nonparametric time-varying (TV) system identification method combined with mode tracking for Operational Modal Analysis (OMA). OMA is a special identification technique for estimating the modal properties of structures based on vibration data collected under real operating conditions and without having access to the excitation signals. The time-varying aspect refers to cases where the structural dynamic behavior changes as a function of time; e.g. due to changes in mass (fuel burn during launch; people filling a football stadium structure) or environmental conditions and interactions (temperature changes; aerodynamic forces causing flutter). In this work a regularized time domain TV OMA method is presented to estimate the linear TV output autocorrelation function of the observed system. In a second step, parametric identification will be applied to track the modal parameters of the time-varying system. The method is illustrated using wind tunnel measurement on an airplane (component) model.