# Relationship of Critical Damping Ratio in Elastomers

Hi guys, working a project where I need to guess the damping ratio (used for a numerical analysis) based on other properties of a material. We're looking to use an RTV as a vibration damper (we don't need a lot) but I can't seem to get any vibrational properties (called Honeywell, Dupond, GESilicones, etc). Hell, if anyone has damping ratios for 'any' RTV, it would help a lot.

If anyone even has a list of any different elastomers with damping ratios, it would help a lot.

edit: Directly related is a properties called $$\tan\delta$$ which I could use as well. Either work.

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Find it experimentally. Bear in mind that its loss tangent will be frequency dependent and can be measured in shear rheology, dynamic mechanical analysis or other method, or just drop a ball of the material from a variety of heights and measure the rebound heights for each successive rebound. Either use a log-decrement method to find critical damping ratio, or relate a coefficient of restitution to the critical damping ratio as shown in http://link.aip.org/link/?JAMCAV/67/831/1 [Broken]

Let me know if you can't retrieve it (I'm assuming wherever you're working has access to it if it's an academic project) and I can LaTeX the expressions.

Edit - if that sounds like a hassle, a decent Elastomers Handbook should have some values at least.

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