I have some problems in understanding criteria of computing MAC.
This my second question on the same topic.
I have an accelerometer on the tip of a wind turbine blade and after exciting it with white noise I got the mode shapes.
I made modal analysis on the ansys apdl and got the mode shapes.
I want to check the pair of modes (experimental and analytic)
What is the simple way to get MAC for both?
How to extract the data?!
"What is the simple way to get MAC for both?"
The MAC criterion check one Eigenvector against another. In the end you get the angle between the vectors. Because each Eigenvector is perpendicular to all the others you get a zero if you multiply them. If they are the same you will get a one.
Based on this knowledge you multiply each measured with each calculated Eigenvector. As result you get a matrix the so called MAC matrix. If the matrix is diagonal dominat (after reordering) your FE model fits with your experiment. The reordering might be necessary because the order of Eigenmodes can be switched.
Eq 6 might help
http://www.ics-solutions.de/papers/Schedlinski_ISMA_2004_2.pdf
if you check "The angle between two complex vectors" you see how it works
http://en.wikipedia.org/wiki/Dot_product#Generalizations
http://www.sandv.com/downloads/0308alle.pdf is a good starting point.
If you send me your cdb file (CDWRITE, ALL) and the experimental mode shapes I will try to send you the corresponding MAC matrix.
The experimental modal shapes could be obtained by simple taking the imaginary part of your FRF in every measured location and plot it, then compare with the numerical modal shapes. A more robust technique to identify modal shapes from experimental data is based on estimation algorithm like least square method. If you already have a shape vector with components in every location from experiment, i think you need the shape vector from ansys obtained in the same location (in your geometry) with the same lenght. In Ansys you need pick the corresponding points. After sorting the modes you can simply build the mac matrix. This could be done in matlab, scilab, python or even excel.
Here are some free: Excel (MACRO) spreadsheets:
http://www.noisestructure.com/products/product.php
These aplications are useful for the analysis of the sound generation chain. You can watch the tutorial videos to learn about the spreadsheets and how to use them. Then, you can download the Excel files and work with your own data.
I am not understanding calculation MAC in mat lab,kindly help me out
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