PSN-L Email List Message

Subject: Re: Spring damping
From: Bobhelenmcclure@.......
Date: Thu, 26 Jul 2007 21:11:23 EDT


I do not know if there is a standard symbol for damping, but "Seismic  
Sensors and their Calibration" by Dr. Erhard Wielandt calls it "h". The relation  
between Q and h is Q=0.5/h. For critical damping, h=1.0 and Q=0.5.
 
  If the sensor Q is set to 0.707, the damping is also 0.707, and  the sensor 
response is identical to a 2nd order Butterworth filter whose corner  
frequency is the natural frequency of the pendulum. The corresponding overshoot  is 
4.33 per cent. This is where I would like to keep my sensors, even  though my 
WQFilter.exe" utility can compensate the data for almost any amount of  
under-or-over damping.
 
Bob
 
  Geoffrey  wrote:
Hello Bob & PSN;
 
Im not so sure this stuff is correct because
its my understanding that Q  and Damping
are simply inverses of each other just like
Period and  Frequency. I was unable to
get the inverse result simply by
alternately  clicking the buttons
using the same input values.
 
Like Q = 1 then damping = 1
Like Q = 0.5 then Damping = 2
Like Q = 2  then damping = 0.5
???
Also, Whats the proper symbol for  damping?



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 I do not know if there is a standard symbol for damping, but "Sei= smic=20 Sensors and their Calibration" by Dr. Erhard Wielandt calls it "h". The rela= tion=20 between Q and h is Q=3D0.5/h. For critical damping, h=3D1.0 and Q=3D0.5.
 
  If the sensor Q is set to 0.707, the damping is also 0.707,= and=20 the sensor response is identical to a 2nd order Butterworth filter whose cor= ner=20 frequency is the natural frequency of the pendulum. The corresponding oversh= oot=20 is 4.33 per cent. This is where I would like to keep my sensors, even=20 though my WQFilter.exe" utility can compensate the data for almost any amoun= t of=20 under-or-over damping.
 
Bob
 
  Geoffrey  wrote:
  Hello Bob & PSN;
 
Im not so sure this stuff is correct because
its my understanding th= at Q=20 and Damping
are simply inverses of each other just like
Period and=20 Frequency. I was unable to
get the inverse result simply by
alternatel= y=20 clicking the buttons
using the same input values.
 
Like Q =3D 1 then damping =3D 1
Like Q =3D 0.5 then Damping =3D 2Like Q =3D 2=20 then damping =3D 0.5
???
Also, Whats the proper symbol for=20 damping?




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