Rod hanger modeling with PTFE between pipe and the clamp

Hello,

I'm trying to model a rod hanger by using +YROD. However, there is PTFE sheet between the pipe and the clamp. This means the pipe can slide through the clamp.

Assume pipe node is 10
Pipe axis = X

Modeling 1:
-----------
Node 10 Cnode 11 Len=1000 +YROD
Node 11 Y
Node 11 Z

Modeling 2:
-----------
Node 11 Len=1000 +YROD
Node 10 Cnode 11 Y
Node 10 Cnode 11 Z

Modeling 1 is not converged and I have no idea to overcome
Modeling 2 is converged and provides reasonable results

I would like to hear any comments.

my last post is a good advice:
"Do not confuse CAESAR II input with actual hardware response in the field"- Dave Diehl

I don't think there is confusing here. This is existing support, and it slides through the clamp.

Any other comments?

In Model 1, node 10 is not connected to node 11 in the Y or Z directions. In Model 2, the Y and Z translations are connected between nodes 10 and 11, in addition to the YROD at node 11.

In neither model do you specify what is happening (restraint or displacement) at node 11. Is node 11 really a free node?

I wouldn't trust very much a support like this. But here is the answer to your question.

1.model the pipe as usual. 10....20....30
2.model the clamp of the hanger as being a very short pipe like 10010..10020..10030. (ambient temp and zero pressure)
3. place an +yrod at node 10020.
4 place a restraint at 20 Y and guide (0.1 friction) with Cnode 10020.

If all the supports will be like this maybe you will receive an error.

Regards,

Actually if you look again at your modeling 1 you will understand that node 11 is restrained on Y and Z respect to the structure, and the pipe (10) is connected to the point 11 through a +Yrod and this model does not reflect what you are looking for.


Assume pipe node is 10
Pipe axis = X

Modeling 1:
-----------
Node 10 Cnode 11 Len=1000 +YROD
Node 11 Y
Node 11 Z