Blind Source Separation Technique for Operational Modal Analysis in Presence of Harmonic Excitation

Abstract

Operational modal analysis (OMA) known as response-only modal identification, is extremely useful for large structures in civil engineering where the excitation is difficult or even impossible to measure. The unknown excitation is always assumed as white noise in OMA. In presence of harmonics, the white noise assumption is not verified that makes the modal identification process difficult, and eventually leading to biased results. In recent years, blind source separation (BSS) techniques have been shown to be robust and efficient for OMA. In this paper, a new BBS technique termed Sparse Component Analysis (SCA) without white noise assumption, is applied for operational modal identification in presence of harmonics. The performance of the proposed method is demonstrated using numerical examples of a two-degrees-of-freedom system and a cantilever beam.