Official Luthiers Forum!

I tried some Chladni testing tonight on an experimental top I'm building. I have no idea how it'll sound but will soon find out. I designed the top using FEA software to a structual load. It is very Smallman-ish in nature. That is a thin skin with carbon fiber topped braces. I used spruce for the brace cores however as I felt balsa was on the edge for a steel string, unless you use it in the end grain orientation, but then it soaks up glue and becomes hard to work. Enough of that side bar.
First let me state that this is an experimental top only and that I have no experience using Chladni paterns to design a top. The real reason for me doing the testing was fro me to gather data to use in refining my FEA models to match reality.
My model showed flapping edges due to the thin skins and my testing indeed showed the same thing. I was able to a few patterns out however that are shown below. I have no idea what they mean, if they mean anything at all.
This top will be on a test guitar in just a few weeks I hope and maybe I'll learn something then.
I'm willling to listen to any thoughts on these.

I tried to add the pictures but got the message "Sorry, the board attachment quota has been reached." any ideas what this means?
I'll try posting them latter.

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Jim Watts
http://jameswattsguitars.com

Too large an individual or combined file size? The guys that know most about this stuff are probably on dialup (I know Al was as of a couple years ago) so you can't post 800K of photos

That's my guess anyhow, unless there are problems board-wide?

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

No I think we have hit a max for the whole board I go the same message on an other topic. I thought it may be a topic issue but it appears it is the Whole shooting shebang

It is the whole board, and Lance is trying to find what the problem is!

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

I'm really interested to hear more about your efforts.

I think the main is question is what are you trying to improve? Are you trying to optimize a standard X bracing design or are you hoping to evaluate potential new designs? What measurement are you using as a means of judging success (amplitude, frequency response, or something else?)? Are you hoping to control dominant modes and/or the overtones? Are you analyzing the free soundboard or the whole guitar assembly? I'm jealous...I used to have a seat of Algor with modal capabilities...but that was before I got hooked on all this stuff!