hi all....

hi all...
i am sorry, i am beginner here and want to know something.
if in 1 node i put 3 types of restraints which all are the same node number of course. then i want to put CNODE for input in displacement. so should i type all the CNODE number on all the 3 restraints or i can just put it in 1 CNODE?
i have so many restraints node which have to put displacement also and kinda lazy to type in.
thx.

The CNODE is an association of degrees of freedom. If you can remember this phrase, CNODES are easy.

The short answer to your question is "Yes", but I wouldn't do it that way. Instead, try this:

- Assuming you just want to displace the node, don't specify restraints at all, just define the displacements. This is because a displacement is a boundary condition, just like a restraint is a boundary condition. So if you want to displace a node (restraint) in XYZ, you would specify displacements in these three directions.

- If the restraint is a nozzle, all 6 degrees of freedom are restrained. If the nozzle displaces, you can specify the XYZ values as above, or maybe just XY. However, the other non-displaced degrees of freedom must have their displacement magnitude set to zero - otherwise these degrees of freedom are free - which is not the case for a nozzle.

- There are a number of examples in the Applications Guide on the use of CNODES. Check the section on modeling Vessel Nozzles.

CNODES are a very powerfull modeling construct in CAESAR II. It is worth your time and effort to study this subject.

LeOnhart,

If your restraints have gaps, making them nonlinear, doing it the way you mentioned makes very good sense. I use this technique when I'm modeling bridge piping where the guides or u-bolts are not tight on the piping. In this way, I can model the displacement of the bridge and allow the pipe to slide through the restraint. It works rather well.

I hope this helps.