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Constrained layer damping adhesive
Constrained layer damping adhesive
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Old 15th April 2015, 02:03 AM   #61
Dave Zan is offline Dave Zan  Australia
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Quote:
Originally Posted by jcx View Post
... it looks like a mostly relevant read - later in the thesis "5-layer" CLD is mentioned
Thank you for the reference, quite informative, "5 layer" CLD does look like it is worth consideration but it was not clear to me that this is what you had in mind.
My comments were about "3 layer" because this seemed to be the context of the discussion, I expect it's easily the most common method for speakers.
The review discussion in the paper supports my comments for a 3 layer system, as far as my initial read reveals.

Quote:
Geddes claims to use...
Seems very reasonable but not common AFAIK. Do you have a link for this one too?

Best wishes
David
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Old 15th April 2015, 02:47 PM   #62
jcx is offline jcx  United States
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https://www.google.com/patents/US7270215
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Old 15th April 2015, 11:37 PM   #63
Dave Zan is offline Dave Zan  Australia
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Thank you, as usual, you are a fount of information.
I don't see Earl's name on the patent, does he license this or just use a similar technique anyway?
It looks line-ball to me whether the idea is "novel" or "obvious to one versed in the art".

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David
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Old 16th April 2015, 01:15 AM   #64
jcx is offline jcx  United States
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if I remember correctly Geddes somewhere says he uses a similar damping bracing technique, may cite yet another patent, and doesn't seem to think it hard to avoid the specific patent claims if he considers any valid - I wasn't clear on his position there
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Old 16th April 2015, 03:20 PM   #65
Greebster is offline Greebster  United States
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I would say versed in the art. I've been using these techniques since the early '80's
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Old 11th December 2016, 11:12 PM   #66
Phenoholic Anonymus is offline Phenoholic Anonymus
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I found this: 3M VHB tape. It's a double sided visco elastic tape. Seems like an easy way to experiment with CLD. 3M? VHB? Tape 4905 Clear, 1/2 in x 72 yd 20.0 mil, 18 per case

Click the image to open in full size.

It's about 10 euro for a square meter in 0.2 mm thickness. And can be bought on Ebay and Aliexpress in small quantities. According to 3M it is the world toughest double sided tape. It's used in automotive to control vibration.

Could be interesting.
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Old 12th December 2016, 02:24 PM   #67
ErnieM is offline ErnieM  United States
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Looks very interesting. I don't see why it wouldn't work.

Thanks for the find.
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Old 22nd July 2019, 12:40 AM   #68
Alfaman1 is offline Alfaman1
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Quote:
Originally Posted by jcarr View Post
Although the structure may seem effective at attenuating vibration, at 5mm I suspect that it is working as a sandwich with an intermediate floating isolation layer, rather than true CLD.

With true CLD structures (which should work better with thin damping layers), it should be possible to screw through all of the layers, while retaining most of the vibration attenuation. If putting screws through the layers impairs the vibration attenuation abilities, the structure likely isn't CLD.

At least when using Green Glue, keeping the damping layer thickness under 2mm appears to work better - 1.5mm should be fine.
This is in response to an old thread on Constrained Layer Damping.
I'm writing because I think you have it wrong.
CLD works by shearing the damping material (CLD dead material/glue/elastomer/whatever - big boys even use lead (I have - not for speakers) - this shearing requires relative motin between the inner and outer "stiff" members.
Basically - you want the inner and outer stiff member to be as stiff as possible, and then the damping material to be as "dead" (highly damped) as possible.
If you are screwing through both layers of the "stiff layers" - relative motion is obviously being restricted.
Screwing though both layers - does create an overall stiffer structure, and the CLD material between layers will add damping - just not in the pretty CLD style.
The "standard" CLD approach is - stiff inner member supporting load, dead damping layer, and then thin but very stiff outer member.
This is how it is done in airplanes - like Boeing and Airbus.
Not trying to be a dick - just trying to be helpful.
If you have a system that works - that is cool - speakers are not as weight constrained as airplanes! - but optimized - this is the approach you want.

I am 35 year shock and vibe engineer - everything from Space Shuttle (old one and new one!) to mining equipment etc. This is how it is done at Boeing and Airbus, where CLD is used like "band aids" to solve resonance problems.

Just fyi -

Best
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Old 22nd July 2019, 05:12 AM   #69
Zvu is offline Zvu  Serbia
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Cool.

Is there some commercially available damping layer material that you'd recommend ?
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Old 22nd July 2019, 02:17 PM   #70
Alfaman1 is offline Alfaman1
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Not that I am aware of - and the guys on this forum are usually quite thorough in their research. I was investigating here. I don't know enough about speaker resonant freq domain just yet to make a recommendation.
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