Tutorial #9 - Operational Modal Analysis (OMA)
Data Block of 99 Acceleration Cross Spectra. DeConvolution Window The 99 Cross spectra will now be curve fit to extract the 10 modes of the original modal model of the Jim Beam that was used by the MIMO Simulator. •
Execute Modes | Modal Parameters open,
to begin curve fitting. The following dialog box will
DeConvolution Reminder Dialog. The message in the dialog box says that a DeConvolution window must be applied to the Cross spectra before they can be curve fit. This window converts the Cross spectra to a form which can be curve fit using an FRF-based curve fitting method. •
Click on Yes to apply the DeConvolution window to the Cross spectra.
Curve Fitting •
Press the Stability button on the Stability tab.
When the calculation has completed, a Stability diagram containing pole estimates obtained from curve fitting model sizes from 1 to 50 is displayed on the Mode Indicator graph. •
On the Stable Groups tab, scroll the slider upward to increase the Min. No. of Stable Poles, and only 10 stable pole groups are displayed, as shown below.
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