PSN-L Email List Message

Subject: Zero Length Spring
From: "Randy" rpratt@.............
Date: Wed, 27 Dec 2006 20:25:26 -0600


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? =
 =20

SpringAngle=3D 25, Force=3D 1.3898, Length=3D 0.2247
X and Y -0.0076,0.1079
TorqueUp=3D -0.000339, Down=3D 0.000337
SeisK=3D 0.6622,  Period=3D 1.44=20

SpringAngle=3D 12, Force=3D 2.4595, Length=3D 0.1783
X and Y 0.0216,0.0501
TorqueUp=3D -0.000337, Down=3D 0.000337
SeisK=3D 0.6604,  Period=3D 1.44

SpringAngle=3D 35, Force=3D 1.0685, Length=3D 0.1797
X and Y 0.0488,0.1161
TorqueUp=3D -0.000329, Down=3D 0.000329
SeisK=3D 0.6454,  Period=3D 1.45








Hi Again,
 
Thanks for the earlier replies.  I = spent a few=20 wonderful days in North Dakota for the holiday so have just gotten back = to=20 it.  Bob can you explain the SeisK in your program?  Is it a = derived=20 spring constant for the geometric conditions created or a stability=20 factor?  I note that negative is always unstable but a negative = length=20 spring does not create instability.
 
I still have not answered my original = question=20 though.   I have 3 examples from Bob's program = below.  The=20 first is similar to a spring I have currently set up.  The second = is a zero=20 length spring with the same spring K and attachment point on the boom = set to the=20 same period.  The third is a softer spring of 0 length.  Given = 2=20 springs and the same period, will one operate noticably better at a = given=20 period in practice?   
 
SpringAngle=3D 25, Force=3D 1.3898, = Length=3D 0.2247
X=20 and Y -0.0076,0.1079
TorqueUp=3D -0.000339, Down=3D = 0.000337
SeisK=3D=20 0.6622,  Period=3D 1.44
 
 
SpringAngle=3D 12, Force=3D 2.4595, = Length=3D 0.1783
X=20 and Y 0.0216,0.0501
TorqueUp=3D -0.000337, Down=3D = 0.000337
SeisK=3D=20 0.6604,  Period=3D 1.44
 
SpringAngle=3D 35, Force=3D 1.0685, = Length=3D 0.1797
X=20 and Y 0.0488,0.1161
TorqueUp=3D -0.000329, Down=3D = 0.000329
SeisK=3D=20 0.6454,  Period=3D 1.45
 
Randy

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