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nerendra.devnarain@gmail. science forum beginner
Joined: 17 Apr 2006
Posts: 3

Posted: Wed Apr 19, 2006 1:48 pm Post subject:
measuring damping coeficient



hi.I am trying practically to measure the damping coefficient required
for steady operation.Plz help what method I can use to measure the
damping coefficient.I have already measured the spring constant for the
material. 

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Tom Sanderson science forum addict
Joined: 22 Dec 2005
Posts: 55

Posted: Wed Apr 19, 2006 2:49 pm Post subject:
Re: measuring damping coeficient



<nerendra.devnarain@gmail.com> wrote:
Quote:  hi.I am trying practically to measure the damping coefficient required
for steady operation.Plz help what method I can use to measure the
damping coefficient.I have already measured the spring constant for the
material.

Assuming it's a "nice" material with a nearconstant spring constant, you
should be able to just set it vibrating and measure the natural decay of the
vibration amplitude...you can back out the damping coefficient from that
data.
Tom. 

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nerendra.devnarain@gmail. science forum beginner
Joined: 17 Apr 2006
Posts: 3

Posted: Thu Apr 20, 2006 9:50 am Post subject:
Re: measuring damping coeficient



Thanx for the reply.But I dont understand what you mean.Could please
explain further.I let it vibrate & do I measure the time it takes to
settle 

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Tom Sanderson science forum addict
Joined: 22 Dec 2005
Posts: 55

Posted: Thu Apr 20, 2006 3:26 pm Post subject:
Re: measuring damping coeficient



<nerendra.devnarain@gmail.com> wrote:
Quote:  Thanx for the reply.But I dont understand what you mean.Could please
explain further.I let it vibrate & do I measure the time it takes to
settle

Don't measure the time it takes to settle, just get a plot (table, whatever)
of the positition vs. time for the naturally vibrating system. Or, you can
do a forced vibration and measure the phase and amplitude difference between
the forcing function and the actual position.
Either way, from that data you can determine the constants in the position
vs. time differential equation for simple harmonic motion (see
http://en.wikipedia.org/wiki/Damping for a reasonable introduction).
Once you know the constants, you can calculate the damping coefficient.
Tom. 

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