CNODE to Model Displacements?

[JackBolt]

Hello all,

I want to model an existing pipe in a piperack and use CNODES to impart a 3" vertical upward deflection to simulate lifting a portion of the pipe with come-alongs. There are no thermal stresses being considered, just trying to see what stresses are induced by lifting a portion of the pipe to make some repairs. The geometry at the point of consideration is a 4" teeing into an 8" which also has a 12" branch. I need to lift the 4" portion of the line 3 inches and want to make sure I do not overstress any portion of the line(s). My question: Is CNODES the best way to model this 3" vertical displacement? If not, please suggest alternatives.

Thanks in advance,

 

[richay]

You really don't have to use CNODES, you can just displace the pipe nodes upward 3".

Richard Ay
Intergraph CAS

 

[DSB123]

Just a point of order. Quote " a 4" teeing into an 8" which also has a 12" branch". I understand a 4" teeing into an 8" but how can the 8" or the 4" have a 12" branch???

 

[JackBolt]

richay - If you model the nodes 3 inches upward, doesn't that just simulate the pipe being 3 inches higher relative to the ground? How would that capture the induced deflection stresses? Or, maybe I am misunderstanding your suggestion of "...just displace the pipe nodes upward..."

DSB123 - yeah I knew someone would have a problem with the wording of my post. Remember, I am a structural guy not a pipe guy. There is a reducing tee which connects the 4" to the 8" which explains the 4" line. There is also another tee which is an 8"x8"x8"; however, the branch portion I was talking about is further downstream where the 8" swedges up to a 12"...I was (incorrectly) calling that a 12" branch.

 

[richay]

I meant:

- check the checkbox for "imposed displacements"
- in the resulting dialog, specify the node number and the magnitude of the desired displacement in the appropriate DOFs.

- later, when setting up load cases, apply the defined displacement vector in the desired load cases.

Richard Ay
Intergraph CAS