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#73001 - 03/11/19 11:55 PM how to read results of XSNB ZSNB in CAESAR
sridhar Offline
Member

Registered: 06/03/12
Posts: 45
Loc: India
Hi,

How to apply the snubber in CAESAR and how to read results please explain me. I need to provide it for Turbine connected piping

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#73007 - 03/12/19 10:36 AM Re: how to read results of XSNB ZSNB in CAESAR [Re: sridhar]
Faizal K Offline
Member

Registered: 07/21/08
Posts: 159
Loc: USA/Malaysia
I would recommend that you start by reading about it from CAESAR II help files. In CAESAR II main window, go to Help tab and press Combined Document Search. Select "In the index named CAESARII.pdx" and Search for snubber.

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#73012 - 03/12/19 10:11 PM Re: how to read results of XSNB ZSNB in CAESAR [Re: sridhar]
sridhar Offline
Member

Registered: 06/03/12
Posts: 45
Loc: India
Thanks Faizal for response,
I was waiting some one give some reply desperately.
I guess my question appeared that I sent without doing homework I am sorry for the same

The point is I have already gone through the help.

"
Static snubbers are translational restraints designed to provide resistance to dynamic loads
such as seismic and wind. Snubbers are activated by checking the Snubbers Active? check
box for the appropriate load case (the one that contains the occasional load) on the Load Case
Options tab in the Load Case Editor. The figure below shows that snubbers will be active in
load case L2 to restrain the pipe against the uniform load.
Figure 20: Load Case Options Tab
Static snubbers, or static analysis snubbers, have SNB following the translational direction that
displays in the restraint Type box (located on the Classic Piping Input dialog box). After you
enter a snubber, Gap and Mu are no longer available.
Static snubbers can be directional. That is, they can be preceded by a plus (+) or minus (-) sign.
To model static snubbers, follow the steps below.
1. Run the operating case without defining a snubber.
2. Note the displacements, in all six degrees of freedom, at each snubber location.
3. In the Classic Piping Input dialog box, add each snubber with a distinct CNode.
4. Place the displacements from Step 1 on all snubber CNodes.
5. Modify the load cases by including D1 everywhere that T1 displays.
6. Activate snubbers in the Load Case Editor for all load cases containing occasional loads.
"

but this process is not giving correct results to my expectaions.

As D1 is added in Ope case, and Still T1 is present it gives additional displacements
for ex. if +X direction displacement is 2 mm in Ope case, after Adding D1 it gives 4 mm as D1+T how is this correct?

same happens in occ case as the D1+T1 is present.

also if I provide X insted of XSNB it gives me same loads in restraint summery, then how to check what use of Snubbber?

What I expect,
In restraint summery
Snubber must show that it takes load only in occ cases and Ope case is no load. and thus nozzle to not show occasional loads as it was showing earlier without snubber.

Please solve my problem, Thanks Million

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#73013 - 03/13/19 07:09 AM Re: how to read results of XSNB ZSNB in CAESAR [Re: sridhar]
Dave Diehl Offline
Member

Registered: 12/14/99
Posts: 2382
Loc: Houston, TX, USA
Those "D1" displacements you mention are applied to the CNodes provided each SNB, not the SNB Node. The T1 in your Step 5 was included in the operating case (Step 1). In your example, the operating case shows a 2 mm displacement in X at, say, Node 200. Add the XSNB @ 200 with a CNode of 201. Define the X displacement of 2 mm for Node 201 (not 200). If you do this correctly, the load case of "operating"+D1 will show zero X load on the XSNB since both "ends" of the SNB are moving in unison. The load case of "operating"+D1+"occasional" will then show the occasional load,only, on the SNB.
[I do not think it necessary to define all 6 DOF as mentioned in Steps 2 & 4). Only the displacements along the SNB vector will be useful.]
_________________________
Dave Diehl

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