Going back through some (elastic) wave propagation texts of mine, this appears to be a necessary boundary condition when using the wave types necessary in periodic structures (i.e. structures composed of repetitive similar units) or composite type structures.

Of course, the boundary conditions are critical in any wave propagation study.....but unless you are doing some unusual nondestructive testing for your field (your discipline is marked as "Civil/Environmental").....I'm not sure how much use it is.

Then again, for all I know, this boundary condition could be used in some spectral FEA software (somewhere) for other applications.

drennon236,

Please do not double post.

thread384-479665: Does anyone understand how Floquet-Bloch boundary conditions work in this context?

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JHG

Yes, if you don't get a response in this forum, then you should probably "red flag" your own post and ask them to remove it due to lack of response and try a different forum.

Note, there is also a Finite Element Analysis (FEA) Engineering forum that you might try if you still don't get much response in the acoustics forum. Your question is probably too esoteric for the Structural Engineering forum.

Quote:

Yes, if you don't get a response in this forum,....

Guess that tells you what they think of my reply.

By the way, I came across this today:

https://www.iap.uni-jena.de/iapmedia/de/Lecture/Co...

It goes into Floquet-Bloch boundary conditions. (And in fairly understandable terms.)

One thing about elastic wave propagation analysis (using spectral FEA software; and to put this as close to "layman's terms" as possible): there are all sorts of elements/boundary conditions to get the appropriate response. (I.e. allow certain waves and frequencies to pass.....and in other cases: get rid of them.) The so-called "throw-off" element is another example. It is a element used when modeling a very long structure where the reflection of the elastic waves would not give a significant response. (Ergo you want to "throw-off" (or out) the elastic wave once it reaches a point.....rather than modeling something too big for your purposes.)