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#64273 - 09/09/15 03:35 PM Deleting Friction values off supports
__Louie__ Offline
Member

Registered: 05/19/11
Posts: 31
Loc: Seattle, WA
I am troubleshooting a model that is not converging. I have found occasionally friction values can cause models to not converge and solve.

My question is, to remove friction from all the restraints, is there a better way than clicking through each restraint and deleting the friction value. I have hundreds of restraints and it takes forever. In addition, I have had CII crash almost every time I click from the list input back to the modeler window. I am at my wits end here. I know there is a way to enter '1' for the mu value and then handle the universal friction in the load case (great update) but some restraints are 0.7 and some are 0.3 so I haven't had great success at getting that process to converge.

Thoughts? I feel defeated.

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#64274 - 09/09/15 04:03 PM Re: Deleting Friction values off supports [Re: __Louie__]
Dave Diehl Offline

Member

Registered: 12/14/99
Posts: 2378
Loc: Houston, TX, USA
There's a global switch for friction. It's in the Load Case Editor (Options). It's a mu multiplier so if you change it from 1.0 to 0.0 you will have no friction in that load case.
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Dave Diehl

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#64277 - 09/09/15 10:03 PM Re: Deleting Friction values off supports [Re: __Louie__]
RK Offline
Member

Registered: 02/24/09
Posts: 173
Loc: India
Be cautious while doing this. Since your results may vary if you exclude friction from your analysis.

Regards,
R.K.

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#64309 - 09/14/15 09:52 AM Re: Deleting Friction values off supports [Re: __Louie__]
Michael_Fletcher Offline
Member

Registered: 01/29/10
Posts: 816
Loc: Louisiana, US
FWIW, I find many/most friction non-convergence issues are tied to lift-off, which typically occurs when you have vertical spans of piping.

If your supports are flexible, then when the pipe will push the supports out of the way, but maintain constant contact. Modeling in the structural steel will define what that flexibility is.

An alternative is to hold the piping down to prevent lift-off, but then you're potentially incurring higher loads, higher stresses, higher costs, etc, to circumlocute a convergence problem.

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#74164 - 11/14/19 06:44 PM Re: Deleting Friction values off supports [Re: __Louie__]
Tom45 Offline
Member

Registered: 11/12/14
Posts: 10
Loc: Canada
It would be great if you could go to the restraint list and select the Mu column and press delete, to get rid of all the friction values
Or
would be great if you could highlight several Mu values and delete them by pressing delete.

Right now when you highlight several values and press delete nothing happens

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#74168 - 11/14/19 07:03 PM Re: Deleting Friction values off supports [Re: __Louie__]
Faizal K Offline
Member

Registered: 07/21/08
Posts: 159
Loc: USA/Malaysia
you can also open Restraints list, select any cell in the Mu column, press ctrl+F. Then use the dialog to find and replace the friction coefficient. Say, find 0.3000 and replace with nothing. It should remove all friction coefficient that matches the search string.
This should work for the current and the past couple of versions of CAESAR II.

this reply was meant for Tom.


Edited by Faizal K (11/14/19 07:04 PM)

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#74176 - 11/15/19 09:50 AM Re: Deleting Friction values off supports [Re: __Louie__]
Michael_Fletcher Offline
Member

Registered: 01/29/10
Posts: 816
Loc: Louisiana, US
In the load case editor, you can set the friction multiplier to 0, and this will eliminate friction for all supports in a given load case.

Of course, you can do this for all of them, as well.

But it's good to know that there's find and replace functionality.

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