Alternative material for damping

[Switch]

Just read the whole thread and saw some interesting ideas for damping. Apart from what all things mentioned here saw that peeps are also using yoga mats to good use :ohyeah:

What I understood from the whole thread is that one should be looking for a self adhesive material which should be about 2-3mm thick and soft enough to bend and dense enough to absorb the shocks & rattles. I am sure many of us come across such materials in our every day life sometime or the other but we never think of the alternate use of such compounds.

Two such compounds I can think of is anti-static mat and vinyal flooring. Both have the qualities as desired by an damping enthusiasts but then comes the question of slef-adhesiveness which is missing in both. As people have already used adhesive compunds and both of these work great with adhesive compounds but I would still rater avoid using them as it is quite a PITA to use liquid bonding compounds. What I am thinking of is a thin flim/sheet/doubble sided tape like material which has adhesiveness on both the sides. Have seen such material in thin strips but would like to procure in big sheet sizes.

If one cant find anything like this then we can always use the liquid bonding compounds and use double sided take to seal the edges.

What do you guys think about the idea.

[DerAlte]

Originally Posted by Switch

... What I am thinking of is a thin flim/sheet/doubble sided tape like material which has adhesiveness on both the sides. ...

At the cost that such material will be available in India (it is not made here), it would be cheaper to use conventional damping material like Dynamat. And more effective!

[Sam Kapasi]

Originally Posted by goandude

Bumping up an old thread.
This guy uses quick roof as a $16 alternative to Dynamat $160. claims no smell even at 90 degrees F.

Bumping up an old response.

Even at 90 degrees F? Umm, that's only like 32 degrees C. Which is pleasant weather in India lol.

Let's talk about 110 degrees F outside in the summer and 120+ degrees F inside a locked car and then hope there is no smell.

[greenhorn]

I've been toying with applying M seal (Epoxy Putty) to a certain area of my door panel which is vibrating away like crazy. Ideally the speaker should be mounted to the door, but thanks to tata engineers, I have to mount them on the door panel. I have already used closed cell foam sheets to reduce vibrations between the door frame and the door panels, but there is this big area right next to the speakers which is blank, is not fixed to any metal, and vibrates away to glory. My plan is that applying M seal would apart from a little mass loading, also strengthen the door panel in that part, and hopefully stop it from joining the chorus. Ideally FG would have been better, or any of the umpteen brands of damping, but am interested in an el-cheapo DIY solution.

Will it work ?

[condor]

how much M-seal do you think it will require ? And why do you think M-seal, which hardens after drying, will work like a damping material ?

[greenhorn]

I think I'll need several 250g packs. thankfully M seal is cheap. my hope is that a layer of hardened M seal, around several mm thick, will brace and reinforce the area of the door pad that is vibrating right now. Have a look at the pics for reference. The area I am planning to do is the part around where the mid bass is mounted, especially the area to the top and left of the mid bass, which is vacant - the pic shows a window handle, but mine doesnt have that also. I dont expect this to work the same way dynamat does - I dont think M seal is that heavy unless I add something to it.This is more as a substitute to applying some Fibreglass to reinforce the door panel.

[condor]

It will possibly come out with time, due to the vibrations.

[greenhorn]

It doesn't bond well with plastic or is it brittle? If it lasts at least a couple of years, thats good enough!

[condor]

I am still not sure about how or where exactly in the door you intend to use it. (I only see the pics of the door panel, inside & outside). To damp, you need something relatively heavy, yet flexible. M-seal is neither.

If in the center, Can you use more layers of foam / synth padding material ?

If else where, will some pieces of tube work ?

[navin]

Originally Posted by greenhorn

I've been toying with applying M seal (Epoxy Putty) to a certain area of my door panel which is vibrating away like crazy. Ideally the speaker should be mounted to the door, but thanks to tata engineers, I have to mount them on the door panel. I have already used closed cell foam sheets to reduce vibrations between the door frame and the door panels, but there is this big area right next to the speakers which is blank, is not fixed to any metal, and vibrates away to glory. My plan is that applying M seal would apart from a little mass loading, also strengthen the door panel in that part, and hopefully stop it from joining the chorus. Ideally FG would have been better, or any of the umpteen brands of damping, but am interested in an el-cheapo DIY solution.

Will it work ?

Originally Posted by greenhorn

I think I'll need several 250g packs. thankfully M seal is cheap. my hope is that a layer of hardened M seal, around several mm thick, will brace and reinforce the area of the door pad that is vibrating right now. Have a look at the pics for reference. The area I am planning to do is the part around where the mid bass is mounted, especially the area to the top and left of the mid bass, which is vacant - the pic shows a window handle, but mine doesnt have that also. I dont expect this to work the same way dynamat does - I dont think M seal is that heavy unless I add something to it.This is more as a substitute to applying some Fibreglass to reinforce the door panel.
Attachment 1041839

Attachment 1041840

M Seal does not have the mass/density of dynamat extreme or it's counterparts.

[DerAlte]

Like any 2-part low plasticiser material, M-Seal will become brittle over time. It will both lose adhesion with the FRP of the doorpad, as well as crack. And yes, as Navin said it is not heavy or dense enough to be of any use.

Best will be at least one layer of FG mat applied with Araldite (less weight, but very stiff). Or 2 layers of 'yoga mat' applied with Fevicol SR (rubber solution). In your situation, IMHO a couple of strategically placed alu or thin steel rods (stuck with Araldite) will do - you just need to break up the large areas into smaller ones.

[anujmishra]

There are bitumen sheets available at hardware store which can be used for damping purpose. I did use such sheets to damp my self built DIY Subwoofer for HT.

It is available quite cheap but only problem is sticking vertically on the door. If someone find the proper glue that can stick it forever, it can be good alternative. These are the roof sheets and it is used with liquid coaltar to stick it. But not sure about smell etc. at 45 degrees temperature.

[greenhorn]

okay, i understand that M seal probably won't work, but my purpose was ( and i know this is the DAMPING thread), i wanted something for REINFORCEMENT. Much like you brace the cabinet walls of a loudspeaker. There is a *LOT* of flex by the body panels in that area, and i dont think there is any metal there - Its a big hollow gap to accomodate the window winder mechanism, which is absent in my case. DerAlte's solution just might work, I'll have to open it up and see if there is any scope of doing that..

[BuildUpGypsy]

This thing has such qualities. 3M-28CT. It's stretchable rubber with adhesive on both sides. 1.65mm thick when not stretched. Used for water proofing telecom cable joints. Had plenty of it while working with a telecom vendor. Almost finished.

[navin]

Originally Posted by greenhorn

There is a *LOT* of flex by the body panels in that area, and i dont think there is any metal there

Originally Posted by BuildUpGypsy

This thing has such qualities. 3M-28CT.

This is sorta related to post 50 on this thread....
http://www.team-bhp.com/forum/produc...-xtreme-4.html (DampMat : Damping Sheets. An alternative to Dynamat Xtreme)

and some earlier posts
http://www.team-bhp.com/forum/ask-gu...damping-8.html (Alternative material for damping)

Lets start with how resonances are damped, absorbed, and dissapated.

Firstly remember that Energy cannot be created or destroyed so all we can do is convert it from one form to another.

Secondly to convert the energy we must first collect it (aka absorb it)

Thirdly we need to disappate this collected/absorbed energy in a non-acoustic manner so that it does not add the mthe music being produced by the speaker.

There are few materials that can absorb low frequencies. Hence bigger panels which support longer wavelengths are better brokedn up into smaller panels there by raising their resonance frequecies.

Once you are in the range of freqencies above 200hz or so, there are many materials that can be used to absorb the sound energy. Polyfil is the easiest to use especially for sealed boxes. About 1/2 kg per cubic foot it a good place to start. Be careful though, overdamping can rob the speaker of it's life. Before Polyfil became common we used fiberglass which was a pain as it required careful handling with gloves. In a car the loose polyfil fibers are a detrement. Hence we use other materials that can be contained easily. Hence they developed sheets of damping material that can be handled and applied easily.

Development of Damping for cars:
As sheet metal used in cars got thinner (due to fuel consumption guidelines) audio nuts started thinking up new ways to damp the thin metal sheets in their cars. One of the methods car audio buffs stumbed on was "constrained layer damping" or CLD. I am sure google will give you 100 links and 1000 times more information and misinformation that I can detail here but the principle is simple (recording studios and DIY turntable isolation-plinth nuts have used the basic principle for over 50 years).

See pictures here
http://blog.acousticfrontiers.com/st...n%20detail.jpg
http://www.newlaunches.com/archives/..._neighbors.php


CLD is basically this: Take material A with medium to high density and good damping (aka ply wood or MDF etc..) sandwich a layer of material B having excellent damping but low desnity between 2 sheets of material A. What you get is a A-B-A sandwich which is more effective than the the same thickness of Material A. It is also lighter and hence stores less energy and the energy stored is quitely converted to heat in material B.

The Mathematics behind CLD is better explained here. Keep in mind that the elastic modulus of structure, viscoelastic material, and constraining layer have to complement each other. http://www.sites.me.vt.edu/unmanned/.../Gallimore.pdf

When car metal got thin the first material used to create a home brew CLD was a sheet of rubberised lead and aluminum (because both were soft and easy to work with and had very different densities). CLD then became MS-Pb-Al with densities of about 7.85, 11.3 and 2.7 (g/cc) respectively.

Soon enough volumes permitted commercialization (lead was replaced by hard rubberized materials due to the fear of lead poisoning) of this and various companies had various products. Some used Butyl rubber (Cascade, DynaMat, BeaverTail etc..) as a base other used cheaper asphalt (Accumat, -Quiet, etc..) . In India asphalt's life is a bit limited because of the heat and humidity here. Butyl rubber also needs some additives to extend it's life.

Dynamat was NOT the first but they did have the best marketing and supplemented that with superb distribution in the US.

Today most Hot Rod manfacturers use some product like this. On TV I have seen West Coast Customs use a liquid called Green Glue and Chip Foose use Dynamat.

Also some manufactuers have started employig CLD to reduce NVH levels. There is even a 3rd party product called Quiet Steel been developed for this process. http://www.matsci.com/acoustic-materials/quiet-steel/ as well as active systems like the one developed by Reiter here http://www.empa.ch/plugin/template/empa/*/85998/---/l=2

BuildupGypsy, 3M has a tape specifically designed for damping vibrations.
http://solutions.3m.com/wps/portal/3...beDQ71HC7GT1gl