Because friction is a value that represents sliding , which is highly variable, this range gives you a "bounded" solution. ie. the upper and lower values are the potential range of results given the state of the frictional contact and its condition.
I generally start with the lowest stiffness giving the highest values of disp and bending loads (ie it slides around a lot) , but you have to do both runs to see the potential for the other end of the spectrum, ie high frictional resistance giving high initial force at the support points to overcome the friction. .Coade manual recommends 50000 which is sort of towards the lower end and is a safe number.
You need the range for another reason; Caesar used to not converge well on runs
with many supports having friction values, ..it is a lot better now with the new
algorithm but occasionally you have to keep increasing the stiffness to get it
to converge....
ie.this numerically sets up a higher force to overcome initial friction
therefore the movement (from the piping model ) is less likely to overcome the
initial force (in the bilinear Friction Force-Disp curve) and move(disP) before
a numerical solution can converge.
From: Alwyn (Al) Kaye
ALTECH ENGINEERING RESEARCH Inc.
9309-96 Str Edmonton, Alberta, T6C-3Y6
Ph/FAX 001 780 465.9762
cell: 780.983.7347
altecheng@primus.ca
Hai Guys,
Can you please advise what is the criteria for setting friction stiffness in CAESAR II control parameters. The value varies from 17513 to 1751300 and results changes greatly with change in setting.
What is the normal value? what is the basis for setting this value?
Regards
Narasimham
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[Non-text portions of this message have been removed] Received on Fri May 23 12:28:00 2003
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