hello all,

I try to modeling an expansion joint.

Download you will find on the following link my ".C 2" and the plan of the expansion joint.

Could you give me please your advice for right modeling?

Thank you in advance

Regards,

http://we.tl/XakB6qqKoK

Rarka,
It appears that you are combining two modeling methods, a detailed model with tie rods (Rigid Elements) and then also spring rate manipulation. You should select one method and stick with it.

The detail model as discussed in the CAESAR II manual should have rigid elements spanning the length of the joint to dummy nodes. You then connect the dummy nodes via C-Nodes restraining the Y, Rx & Rz axis.

A spring rate manipulation model would use a zero length expansion joint, no tie rods (rigids). You should also set the OAL of the joint to ambient temperature.

Dan Edgar,

Thank you very mich for your reply.

However, I do not see what is the best modeling ...

From what I understand, if the detailed method is used, it should not return values ​​of stiffness?

I looked in the application guide to modeling my expansion joint but I confess I am lost ...

According to you, what should I change my model for the expansion joint is correct?

Would you a model. CAESAR II with the two models?

Thank you in advance

Regards

Rarka,

I've corrected your model and it should be attached. I've made the following changes:

1) Change the Tie rod rigid elements to one rigid element spanning the entire length of the joint with a dummy node at one end.
2) Connected the dummy node to the line node via C-nodes.
3) Revised the tie rod temperature to ambient.
4) Deleted the bending stiffness which was rigid.
5) Entered an estimated effective diameter. You should enter the actual if you have it. It will effect the pressure thrust load on the tie rods.
6) You should enter the actual axial and torsional stiffness's if you have them. If you don't have them, then you should enter a low number. You can consult the manufacturer's catalog for approximate numbers.
7) You should confirm that the lateral spring rate is the single bellows spring rate and NOT the universal spring rate.

I hope the above is of assistance.

Dan Edgar,

I understood everything about the modeling of this expansion joint.
Thank you very much for your help. Your advice is invaluable.


I have to model a second and last expansion joint: Hinged joint.

Download you will find on the following link the beginning of my modeling .CAESAR II and the plan of the expansion joint.

http://we.tl/BH19lDHoM1

I model the expansion joint with a zero lenght but I do not know how to apply my restraints ...

Could you give me advice for right modeling?

Thank you in advance

Rarka

Rarka,

Unfortunately the picture you included doesn’t allow me to read the dimensions, so I can’t offer specific information. However I can offer some comments:

1) Due to recent changes in Caesar II you can no longer use a zero length expansion joint with a restraint, this only affects hinge joints. So, you will have to do a detailed model.

2) Enter the actual bellows length. This should be the convoluted length only and not the tangent to tangent dimension shown on the drawing.

3) Enter the actual bellows spring rates, axial, angular, torsional and effective ID. Omit the lateral.

4) Create two rigid elements, one spanning from the inlet to the center line of the bellows and the other from the outlet to the center line of the bellows. The rigid elements should be set at ambient temperature.

5) Connect the two rigid elements via c-nodes and restrain X, Y, Z, Ry & Rz.

Consult the CAESAR II manual for additional information.
I hope this helps,
Dan

Dan Edgar,

I understood about the modeling of this expansion joint.
Thank you very much for your help. Your advice is invaluable.

Regards

Rarka