sound deadener brands

[FoxPro5 5,000+ posts]

Yes i understand that but correct me if im wrong but the thicker mat having more mass basically can convert more motion into heat, i know i does not always work this way but that in theory it should correct.I know the foil thickness is a big factor which is why edead with its mylar backing is not as effective

Not mass, viscoelasticity which depends on the nature of the materials involved. This is why an adhesive-backed extensional damper will out perform a CLD mat in many car audio apps, especially on a driver mounting surface. Something like Parts Express heat-formable damping sheets will probably out-damp most of the CLD mats in that application, despite being lighter.

How can plastic film "constrain' anything? You can rip eDead's backing with your bare hands like you can plastic wrap. You can't really do that with aluminum foil. Maybe we should be looking in our kitchen drawers for "deadening" materials rather than buying some the crap that's sold to us as "deadener?" //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[FoxPro5 5,000+ posts]

If you know how to test and show proof-positive which mat works best, Id love for you to tell me too.

http://www.astm.org/Standards/E756.htm

Levels the playing field for damping.

"works best" may be a number of things including ease of application, life-expectancy of the materials, etc.

 

[Rudy 10+ year member]

If you know how to test and show proof-positive which mat works best, Id love for you to tell me too.

I really wish that was practical. In the first place, ASTM-E756 testing costs $600 per sample. This would be great if everybody would agree to the methodology, test their own products and publish the full results with authentication. Unfortunately there are already a lot of bogus numbers floating around. Tkis puts legitimate manufacturers at a disadvantage if they choose to publish honest results.

I had some pretty extensive discussions with the guy who runs Damping Technologies. My idea was to contact the manufacturers and ask them to submit a sample directly to Damping Technologies, pay the fee and authorize him to send me a copy of the results. This would guarantee fairness and give us something to work with.

The reason that I gave up on this idea was that it really an bass ackword way of using the tests. The appropriate use is in finding the optimal solution to a specific problem where you know the exact specifications of the substrate to be damped - size, shape, mass, operating temperature, etc. When you know those things, you test materials for that exact application.

Here's one of his e-mails:

Don:

1.) Since the market you are talking about is by-definition "cut and paste", I would suggest that each of the candidate materials be tested at least on the (0.032" thick) SAE J1637 cantilever beam test article as a function of temperature. Immediately, that data is going to reveal (for each material) where the modal loss factor is going to peak with respect to temperature. Every one of these materials is going to exhibit a bell-shaped curve for modal loss factor with respect to temperature. This very basic test is going to demonstrate, within reason, where the peak damping occurs (as a function of temperature) for each candidate. That's the absolute minimal information that's going to allow some guy working in his garage select the proper material. Some of these will probably peak at (20 F). Some will peak at (75 F). Who knows? Obviously, if the temperature at the application site is (75 F), this will narrow things down tremendously. That's the first thing that I'd do.

2.) After that, you might think about repeating the tests with a second layer of each material applied for reference. I expect that you'll probably get somewhere around twice the damping in that case, but that's not always exactly true. If people are layering these products commonly, then why not generate the data and see what it tells the user? From this set of tests, the user could get some idea regarding the benefits (with respect to damping) of layering the materials.

3.) The other key item that you might want to "list" for the users is the weight of each damping system. If the application is noise control, mass is your friend. Acoustic transmission loss will increase with mass. So, the heavier the product, the better the acoustic transmission loss. Keep in mind that acoustic transmission loss is the ability of the material to "block" the sound pressure waves. This is a seperate issue from damping. Damping should loosely be thought of as the material's ability to attenuate the resonance response (vibration) of the structure. Now, that resonance response often generates noise (sound pressure). So, if you attenuate the vibration response of the structure you tend to attenuate the radiated noise from the structure. So, that's how damping helps with noise control. However, transmission loss is a seperate mechanism of noise control and the more mass a product has, the better the transmission loss (in general). So, that's potentially an important factor in selecting one of these materials. As long as I didn't care about adding weight to my vehicle, I'd select the material with the best damping and the most mass, if I were interested in noise control.

4.) Liquid products would need to be coated to the SAE J1637 base beams in some thickness. You'd have to decide what thickness is typical.

5.) If it were me, I'd definitely test all of the candidates using SAE J1637 in a single layer. If people commonly layer the products, then you might think about running a second set of tests with two layers of each material applied. Then, I'd be sure to document the (lb per ft2) of each candidate for those who are interested in making their vehicle quiet............... I realize a lot of these guys are using this stuff to keep their various body panels from rattling when they install the jumbo sub-woofers, etc. So, not everybody would realize the benefits of the mass additions. But the guy trying to achieve a quiet interior would want to select the product with high damping at the operating temperature of interest combined with the highest weight density (as long as he doesn't mind weight addition to his vehicle).

Hope this helps.

Best wishes,

- TOM

So yes, test results would be somewhat helpful, but at what temperature, at what panel size and thickness and then how do your account for price and weight. Left me thinking that the best we can do for general purpose application is extrapolate from adhesive quality, mass and foil thickness. I know I'm not interested in buying six different vibration dampers for different areas of the car.

 

[FoxPro5 5,000+ posts]

Never going to happen. Our cars are probably not considered "critical" for overall weight. Aircraft, an F1 McLaren or the Space Shuttle (who Damping Tech probably works for) are. Still, we obviously don't want to weigh down our cars. Which is why I personally have found that saving the weight for the barrier app to be better than this whole "mass loading" to kill vibration.

But, that's great you sought that out, Don. I'd love to see the results. It would put some companies out of business, though. //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif