Learn About Vibrations!

Learn About Vibrations!

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The ABRAVIBE blog is where you find all the resources for learning more about vibrations. Browse and download examples for the free MATLAB/Octave ABRAVIBE toolbox. Or browse the many theory examples, videos, and resources for the book "Noise and Vibration Analysis: Signal Analysis and Experimental Procedures," by Anders Brandt!

Modal Analysis Example and Important Upgrade for Modal Parameter Extraction

ABRAVIBE ExamplesPosted by Anders Brandt Mar 09, 2013 15:48
The ABRAVIBE example PlexiModal is an example of using the ABRAVIBE
toolbox to do experimental modal analysis of a Plexiglass plate using measured data.

The example uses data measured using impact testing, and the
polyreference time domain (PTD) method with two references, to be able to
estimate the first two modes which are strongly coupled on this plate.
The example shows all involved steps such as importing and sorting data,
curve-fitting for poles and mode shapes, and evaluating the results with
a MAC matrix and animation of the modes.

This example is good to use as a template for all modal analysis tasks
with the ABRAVIBE toolbox; just replace the data imported, and the
geometry created before animation, to use the script for your modal
analysis tasks!

In addition to this, the example includes an upgrade to the ABRAVIBE toolbox revision 1.2, with a new command enhancefrf which uses singular value decomposition to reduce the measured FRFs into a smaller number of principal responses to use for the modal parameter extraction. Also the command frf2ptime is updated to use FRF enhancement by default. These two functions will be included in the next release of the ABRAVIBE toolbox. The theory of FRF enhancement is covered in chapter 15 in the book "Noise and Vibration Analysis".

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