Unity Method for EMA and OMA in Frequency Domain

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Journal of Vibration and Shock ›› 2016, Vol. 35 ›› Issue (12) : 7-12.

DONG Lei 1??Zheng Tiesheng 1??SONG Hanwen2

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Abstract

The complexity of system dynamics characteristics is increasingly outstanding due to the trend of the tested objects turns from isolated components to the integral structures. Local behavior of the components and closely spaced modal increase with this complexity Exertion or measurement of the excitation is almost impossible for large-scale structures. Only the outputs is available, in which case OMA is issued. While the complexity of the system and the difficulty of analysis increasing, the higher analysis highlights current limitations of modal analysis process Several difficulties: analysis of the complete frequency band simultaneously, high system orders, the large number of measurements to be processed, exist both in EMA and OMA process. Specific mathematical models between EMA and OMA made no universal method for modal analysis. The present paper reviews the theory of VF，extends VF method to OMA. A coherent model description and Unified identification process are presented for both EMA and OMA in frequency domain. The implementation of the analysis in the whole frequency band at the same time is obtained by using a high model order (over 100), which simplify the identification process. The decrease of identification quality could be avoided by the reduction of user interaction An EMA case is discussed, which validates the VF method when it is applied to large number of FRFs (over 1000) with significant data noise. The excellent result is also confirmed in the OMA case study.

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EMA / OMA / Modal Parameter / Frequency Domain / Unity

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DONG Lei 1??Zheng Tiesheng 1??SONG Hanwen2. Unity Method for EMA and OMA in Frequency Domain[J]. Journal of Vibration and Shock, 2016, 35(12): 7-12

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