damping ratio
damping ratio
(OP)
Can anyone tell me how to run a simple (ball-park) test to determine the “Damping ratio” of an unknown material?
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RE: damping ratio
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: damping ratio
RE: damping ratio
Clap your hands in a reverberant room damped by your material, use a microphone. Proceed as in previous post. Filter the time signal into frequency bands.
This is unlikely to be accurate.
otherwise use an impedance tube, intensity, a sound transmission loss suite, etc etc. Or hire someone who knows the basics. it is Acoustics 101 after all.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: damping ratio
Isn't this the standard first approach to all problems?
RE: damping ratio
RE: damping ratio
Tobalcane
"If you avoid failure, you also avoid success."
RE: damping ratio
RE: damping ratio
Generally you ask the supplier for measurements or samples. Sorry, there is no satisfactory way of calculating the damping of teatments, so far as I know everybody tests them. You can build models of them which might work for tuning, once you have a concept in place with a measured response.
Specifically with regard to acoustic treatments you may get a fair bit of snake oil from the salesman, especially using multiple layers to give optimum damping at some frequencies. For some reason these work better in the lab than on the road.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: damping ratio
RE: damping ratio
Performing this test with the test material in the room and without the test material in the room should give an indication of the material properties.
As an acoustic consultant, I'm sure you know how to relate decay time to room constant, and room constant and material surface area to material unit properties.