clarification on damping broadening peak
clarification on damping broadening peak
(OP)
I came accross an old thread and wanted to make a small comment, but thread is closed:
Here is the thread
http://www.eng-tips.com/viewthread.cfm?qid=160351
It was stated:
This seems incorrect to me, at least by study of a SDOF system: Here is an example (which I'm sure is nothing new to anyone here).
http:// home.comca st.net/~el ectricpete /eng-tips/ SDOF_VaryD amping.pdf
Increasing the damping does broaden the shape of the peak, but the amplification at any given frequency is lower as we increase damping, correct?
Here is the thread
http://www.eng-tips.com/viewthread.cfm?qid=160351
It was stated:
Quote:
Bear in mind that damping will broaden the peak as well as reducing its height, so increasing the damping can actually increase the response at a particular speed.
This seems incorrect to me, at least by study of a SDOF system: Here is an example (which I'm sure is nothing new to anyone here).
http://
Increasing the damping does broaden the shape of the peak, but the amplification at any given frequency is lower as we increase damping, correct?
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RE: clarification on damping broadening peak
"so increasing the damping can actually increase the response at a particular speed."
was wrong, for your simple SDOF system.
BUT, there are many more complex systems where adding damping does increase the off-resonant response, eg increasing the damping levels in a shock absorber. You see the same in engine mounts, diff mounts and suspension bushes.
Nice catch.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: clarification on damping broadening peak
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Eng-tips forums: The best place on the web for engineering discussions.
RE: clarification on damping broadening peak
So, in the case of a driveshaft, it might well be closer to yuor SDOF example.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.