Elastomeric and AV mounts

[fluff]

Hi, I just have a couple of areas i need some input on:

1/ What is the current state of the art for elastomeric mounts over the full -55 to +80 deg (ish) temp range - resonant frequency stability and damping? What suppliers are the leaders in this field?

2/ What is the state of the art in active AV mounts were limited space and weight is the main consideration?

Thanks in advance

John

 

[Highspeed]

From my experience, vibration damping with elastomeric material to be efficient needs alot of experimentation.
What i did found when limited space is available :
3M™ Ultra-Pure Viscoelastic Damping Polymer 242F04
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http://products3.3m.com/catalog/us/...vetape_3_0/command_AbcPageHandler/output_html

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but that was for a high speed application

The other way I used in the past is to work directly with a silicon manufacturer (NUSIL in my case) to play with different formulations.

Good luck

 

[fluff]

Thanks for quick reply! The AV mounts are for an optical bench which will be exposed to broadband excitation, and fairly high G loads (10g ish)

John

 

[okdb]

Hello,

Try this manufacturer: Trelleborg-Novibra

http://www.trelleborg.com/industrialavs/

They know what they're talking about, have a wide range of product and they sell almost every where in the world.

OkdB

 

[fluff]

Think i need to clarify thing a little! The term optical bench may not have been correct... The bench i refered to is ptobably better described as a isolated (by the required av mounts) bed within a airbourne electro-optical system. I think 4x8 cast iron tables would causes some take-off problems...

 

[pjhype]

John,

Elastomeric mounts may give you a problem under the wide temperature range and high g-loading for aircraft applications. You might want to consider helical isolators:

http://www.springcompany.com/jes2/isolframe/isol.html

pj

 

[tomaspin]

Hi Gents,

A well specified elastomeric 'hydromount' with built in low frequency hydraulic damping could be the answer, as they exhibit high dynamic stiffness, and are able to absorb high 'g' shocks. Freudenberg (

http://www.simrit.com)

and Continental (

http://www.schwingmetall.de)

and lord all have these parts. -50 to +80c should be possible with these parts. Barry Controls also have a range of air damped parts for instrument mounting applications.

Regards

Tom

 

[chrbiss]

The natural frequencies of a system using elastomeric mounts will widely change over a -50 to +80 deg temp range. I don't think using hydraulic damping would be the best way to solve your problem because they are temperature dependant."highspeed" talked about silicon, this is the best elastomeric material to use at low temperature.

Lord developed a friction mount which acts almost like a hydraulic mount but without the temperature dependance. Coupling it with silicon in some way (keeping in mind that silicon does not have good abrasive resistance) should give you pretty good dynamic properties.

I suggest you find silicon suppliers who have a NVH lab. Their engineers shoulb be able to work with you and find (or create) the best solution for your application. If you look for a large quantity of mounts yearly, Lord should do it for you. If not, go to a small rubber company.