Abstract
Operational modal analysis (OMA) has been utilized to extract structural dynamic characteristics by only using the output responses. In many cases of OMA, the problem of harmonic components, which is caused by periodic excitation components to the structure, may occur, and may lead to erroneous modal identification. In this paper, an optimized harmonic indicator function named the enhanced spectral kurtosis (ESK) is proposed to improve the effectiveness of the harmonic components detection. Moreover, a new algorithm based on virtual excitation assumption is presented to remove the harmonic components in modal parameters estimation. Finally, the quality of the proposed method is compared with that of the conventional method using a numerical simulation and a practical experiment.
Highlights
During the last decade, the modal analysis becomes a key technology in structural dynamics behavior study [1, 2]
Harmonic components make a difference in the dynamical response of many structural or mechanical systems which are excited by periodic loads
It is a challenge for many Operational modal analysis (OMA) techniques to detect and remove the harmonic components
Summary
The modal analysis becomes a key technology in structural dynamics behavior study [1, 2]. The harmonic components, in other words, are assumed to be zero-damping modes in this method Another method based on the probability density function (PDF) of the output for distinguishing a harmonic response from narrowband stochastic responses is widely used [9, 14, 15]. This method, is effective when the harmonic frequencies are well separated from the structural frequencies, since it would imply that temporal filter must be used. An application of the proposed method to detect and remove the harmonic component of a GARTEUR (Group of Aeronautical Research and Technology in EURope) aircraft model is presented to demonstrate its procedures and credibility
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