Vibration Dampening Material Suggestions

[MrKlinky]

But there's no physical basis for that rule - viscous friction isn't directly related to mass or density.

My apologies; I purposely omitted the obvious, that the mass rule of thumb stated is based around industry standard viscoelastic damping materials, not toffee/carpet/chewing gum...

 

[ulogon]

A general rule used in industry is that the mass of damping material should roughly equal the mass of the panel to be damped

That's interesting, thanks.
It explains what I've always guess without ever being able to detail it to myself.

But there's no physical basis for that rule - viscous friction isn't directly related to mass or density

I'm not aware of the lack of this rule and therefore I kindly ask you to detail it for me, please.

However, if I may, I guess that "viscous friction" is related to the characteristics of a material, and among its characteristics there will certainly also be mass.
So I wonder if a material with high "viscous friction" characteristics doesn't also have high damping capacity and high mass.

 

[Mark Tillotson]

Tungsten has high mass and no viscous friction, foam rubber has high viscous friction and low mass.

 

[ulogon]

I got it, thanks.
But then I conclude that "viscous friction" is not the first characteristic I look for in a dampening material to reduce the resonances of a panel.
Furthermore, it's clear enough that no one would use tungsten to dampen the resonance of a metal panel.
So, in my eyes, the mass of a dampening material does matter more than its "viscoud friction" factor.
Did I omit any step?

 

[Mark Tillotson]

To dampen a resonance a material has to dissipate the energy by some mechanism, usually as heat via friction (solid or viscous) - this is what a shock-absorber in car suspension does and it doesn't use mass to do its job, it forces oil through small channels to generate heat by friction. The only reason mass is required fundamentally is to absorb and spread the heat generated, it doesn't directly do damping.

 

[geoffkait]

Marigo sells these very cool constrained layer damping VTS dots, different sizes for everything from the bottom of electron tubes in between the pins to the wall, to speakers to electronics chasses to glass windows, you name it.

 

[ulogon]

May be of interest

https://soundskinsglobal.com/pages/sound-damping-vs-dampening-vs-deadening-whats-the-difference

 

[ceulrich]

Hello All,

Thanks for all the suggestions and comments.

I never would have thought of a product made for the automobile industry!

The Mortite Caulking idea is interesting, but I wonder about bonding to the underside of a chassis top panel?

The Butyl deadening material looks interesting, and at 10 sq ft for $27.00 is priced right.

Doing the “Google thing”, I came up with AcousTech’s vibration dampening material sold by Acoustic Sounds. It is kind of pricey, at $15.00 for a 4” x 6” sheet. Acoustic Sounds claims the product works via “Hysteric Damping.” Anyone had any experience with this product?

Cheers,
ceulrich

 

[planet10]

Mortite Caulking

Ductseal works better. By more than a bit. I have tried both. And plasticine, and, and...

https://www.t-linespeakers.org/design/tweeks.html (second bit)

 

[geoffkait]

Of course, vibration isolation shoukd nit be overlooked in the quest for ridding vibration, the lowest frequencies are the worst offenders. vibration isolation is a two way street it allows vibration to be shed from the component and reduces low frequency vibration coming up from the floor.

 

[MrKlinky]

“Hysteric Damping.”

'Hysteretic', perhaps?

 

[Terry2000]

It may sound odd but I am using 3.5mm thick vinyl flooring leftovers. It has surprisingly high density. I also use it to damp inside of spkr cabinets. I secure it with double sided carpet tape.