NEWBIE QUESTION : RBE3 problem or something else !? 1

[Davoue]

Hello every one,

I'm new at FEA Advance Simulation in NX9.

I have two parts one '' A '' is fixed and the other '' B '' is on top of it.

I made some RBE2 connections between the two parts.

At this time I can solve my solution.

But the part '' B '' is bending in the middle of it. I want it to lay down on the part '' A '' to see deviation of the part '' A '' when it support the weight of the part '' B ''.

I've been told to use RBE3 connections between the two parts because I don't want them to be rigid...

I connected the two parts with one nod on each parts.

The solver in .f06 give me fatal error :

*** USER FATAL MESSAGE 2038 (RBE3D)
RBE3 ELEMENT 51 IS SINGULAR.
USER ACTION: ADD MORE DOFS TO THE CONNECTED POINTS TO INSURE THAT THEY CAN CONSTRAIN ALL 6 RIGID BODY MODES
OF THE ELEMENT.

I tried to manually play with different DOFS configurations in mesh associated Data. I cannot find what is wrong with my RBE3.

Do I use the wrong connection ? Maybe it is a problem my nods are not really co linear?

I tried to find out what I'm doing wrong in this forum and I found nothing.

I hope you can help me folks to find what is my problem and BTW the your eng-tips forum are very helpfuuuulll!!!!

 

[Naffoussi]

I think you have to use more than one node (at least three) on part B for the RBE3 connection. Such that you avoid the rotation of part B around its axial direction...

Seif Eddine Naffoussi, Stress Engineer

http://www.Innovamech.com

33650 Martillac û France

 

[Davoue]

Merci Monsieur Naffoussi! It works fine now ! I have to connect every nod one to another, I have a big parts with lots of nods to connect together. Do you have any suggestions if I want to connect them in a faster way !?

 

[Naffoussi]

are you using Femap?

Seif Eddine Naffoussi, Stress Engineer

http://www.Innovamech.com

33650 Martillac û France

 

[Davoue]

In Simulation NX calculated with NASTRAN...

 

[Davoue]

Sorry, I build my model in NX and use it in NX Nastran Fem and NX Nastran Simulation...

Mechanical designer
STYL&TECH inc.

http://www.stylntech.com

 

[Naffoussi]

I don't know how to do it with NX but i think it feasible. With Femap you have the ability to select two sets / groups of nodes and then create multiple RBE with one click.
Post your question here (NX group):

http://www.eng-tips.com/threadminder.cfm?pid=561

Seif Eddine Naffoussi, Stress Engineer

http://www.Innovamech.com

33650 Martillac û France