Operational Modal Analysis of Rotating Machinery Using a Modified Frequency Domain Method

Operational modal analysis can be used as a useful method for modal identification of rotating machinery. Response of a rotary machine contains several powerful harmonic components which make the OMA methods face several problems. In this paper, kurtosis index is used for detection of response harmonic components. Then, CFDD method is modified for removing the harmonic effects and extracting the modal parameters. Accuracy, applicability and computational efficiency of the proposed method are evaluated through computer simulation of a 4DOF system, an operational modal analysis experiment on a steel beam, and operational modal analysis of a large industrial fan in Mobarakeh Steel Complex.