Physics/math help needed; plate resonance

Hey all, I know we have some pretty clever cookies at HSBNE, and was wondering if anyone knows a few things about natural resonance of plates?

I would like to be able to calculate, for a given material type, thickness, and length/ width, with constrained edges, the natural resonance.

For bonus points, I would like to be able to calculate how much energy, at the resonant frequenciy, is needed to excite resonance.

Are these questions reasonable, or is the math involved obscene.

All math is obscene.

For an essentially flat plate, with a central emitter/generator, a good rule is that f0 will be about 2*radius / speed of sound in that material.

How to measure the speed of sound?

Put a post in the middle of a round plate, attach a function generator to an amp to a beefy speaker to the post, put a bunch of rice or salt etc. on top and sweep frequency until you get the first nice pattern.

Try for an artistic take

Measure the RMS on a 1ohm resistor on the speaker line.


That’s awesome thanks! Problem is I don’t have a plate I want measured, rather I’m designing something and need to figure out what to use before I purchase. I did find a MATLAB script someone put together that might work, just haven’t had time to test it.

Thanks for the help though, and I’ll remember that trick for sure.