Bracing VS Damping

[andy19191]

Yes. It is a hard problem to analyze / simulate correctly. Not impossible, but hard. Someone who knows what they are doing with FEA needs to spend some time on a given design in order to arrive at a valid analysis.

I started to put together an article a year or so back using open source FEA only to find that viscoelastic damping models weren't implemented. It would have been possible to put something together without but when studying resonances getting the damping reasonably correct is required to get the amplitudes of the resonances reasonably correct. Instead I added implementing one to the to-do list but haven't got round to it yet.

 

[Bmsluite]

Also, Turbowatch2 makes the correct claim that any sandwich material needs to be viscous. Sorbothane is an obvious material but quite expensive. But finding information on the viscoelastic measures for neoprene, butyl rubber, etc, is difficult. I thought I had found at one time that neoprene was not viscous and butyl was, but I have not been able to confirm that.

3M VHB double sided tape is viscoeleastic material. Easily sourced and cheap.

The bolt with rubber washer is a good idea and makes sense to me. I don't think I'll need the rubber as the bolt will be secured to the brace but the brace will be elastic itself. I'm going to see if I can find an adhesive that will bond TPU and wood as I think that is the simplest, most elegant, solution.

 

[gaszto]

Yes. It is a hard problem to analyze / simulate correctly. Not impossible, but hard. Someone who knows what they are doing with FEA needs to spend some time on a given design in order to arrive at a valid analysis.

😀
I can confirm that.
The journey starts with the material properties. I spent a couple of days to try to model the MDF material properties. (Anisotropic) At the end the measured resonance frequency of each cabinet wall was surprisingly close to the simulated result.

 

[markbakk]

but this reduces the mass the moving cones react against which tends to be fine for tweeters, debatable for mids and a problem for woofers.

For a typical mid the ratio cone weight/total weight is in the order of 2%. Since panel resonances appear at mid frequencies, you could skip the woofer and tweeter. I don’t really see the issue, apart from the assumption that in normal conditions modest panel resonances would be problematic, is debatable itself.