Difference between revisions of "Modal practical"

Modal practical (view source)

Revision as of 08:26, 17 July 2020

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→‎OPERATING DEFLECTION SHAPE

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 ===OPERATING DEFLECTION SHAPE===
-[[Image:Modal_practical_04.jpg|framed|none]]
 In the operation tree, double click on `ODS: Freq Domain   The following interface is displayed.
+[[File:ODS.png|framed|none]]
 On the left, the Modal Indication Function (MIF) shows the modes in the frequency band. Position the cursor on the peaks and visualize the corresponding mode shapes on the right.
+[[Image:Modal_practical_04.jpg|framed|none]]
-'''''What is the MIF?'''''
-MIF can be employed in not only EMA, but also OMA. In EMA case, the number of MIFs equals the number of excitations or references. In OMA case, the number of MIFs equals the minimum number of responses of each setup. The MIFs consist of the singular values of frequency response function matrix (FRF), output power spectral density matrix (OPSD), or half power spectral density matrix (HPSD).
-By the powerful singular value decomposition, the real signal space is separated from the noise space. Therefore, the MIFs exhibit the modes effectively. A peak in the MIFs plot usually indicate the existence of a structural mode, and two peaks at a same frequency point means the existence of two repeated modes. Moreover, the magnitude of the MIFs always implies the strength of a mode.
-Two separated modes
-Weak modes
-Two pairs of repeated modes
-Sometimes we should note the cross modes. For example, in the below figure, the peak in the second MIF curve doesn<nowiki>’</nowiki>t indicate a mode. It<nowiki>’</nowiki>s formed by the cross of two modes.
 ==MODAL ANALYSIS USING EMA BROBAND==

Difference between revisions of "Modal practical"

Modal practical (view source)

Revision as of 08:26, 17 July 2020

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