Identificación de modos cercanos de vibración de una estructura cuasi-axisimétrica: estudio complementario

Abstract

A procedure for the characterization of so-called close vibration modes is presented. These are modes with similar natural frequencies that commonly appear in quasiaxisymmetric structures. Their characterization is usually hindered because their resonance regions overlap significantly, and thus conventional characterization methods based on single-degree-of-freedom curve fits cannot be used. The proposed procedure is based on performing simultaneous estimations of the parameters of the two modes, employing the fewest possible response data points in the frequency domain. The modal parameters are directly related with the differences between the response measurements at different excitation frequencies. The main contribution of this work is a modal characterization method that is designed specifically for the identification of close vibration modes and which, in contrast with the well established analysis methods, does not require that each resonance region be dominated by a single mode of vibration. The application of the procedure to the case of a real structure demonstrates that it is possible to estimate the modal parameters of close vibration modes using a reduced set of vibration response data, and yields satisfactory results even in the presence of measurement noise.