PSN-L Email List Message

Subject: Re: Zero Length Spring
From: "Geoffrey" gmvoeth@...........
Date: Thu, 28 Dec 2006 08:29:55 -0700

I understand Damping and Q
are simply inverses of each other.
Q is quite complex in that it
requires the knowledge of the
3db (0.7071) cutoff points as
relating to the frq of interest.

Can anyone tell me the proper way
to express damping ??
I sort of understand Q but not
how you arrive at the proper numbers
for damping alone.


----- Original Message ----- 
From: "Randy" 
Sent: Wednesday, December 27, 2006 7:25 PM
Subject: Zero Length Spring

Hi Again,

Thanks for the earlier replies.  I spent a few wonderful days in North Dakota for the holiday so have just gotten back to it.  Bob 
can you explain the SeisK in your program?  Is it a derived spring constant for the geometric conditions created or a stability 
factor?  I note that negative is always unstable but a negative length spring does not create instability.

I still have not answered my original question though.   I have 3 examples from Bob's program below.  The first is similar to a 
spring I have currently set up.  The second is a zero length spring with the same spring K and attachment point on the boom set to 
the same period.  The third is a softer spring of 0 length.  Given 2 springs and the same period, will one operate noticably better 
at a given period in practice?

SpringAngle= 25, Force= 1.3898, Length= 0.2247
X and Y -0.0076,0.1079
TorqueUp= -0.000339, Down= 0.000337
SeisK= 0.6622,  Period= 1.44

SpringAngle= 12, Force= 2.4595, Length= 0.1783
X and Y 0.0216,0.0501
TorqueUp= -0.000337, Down= 0.000337
SeisK= 0.6604,  Period= 1.44

SpringAngle= 35, Force= 1.0685, Length= 0.1797
X and Y 0.0488,0.1161
TorqueUp= -0.000329, Down= 0.000329
SeisK= 0.6454,  Period= 1.45



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