Symmetry loads and RBE3

[aleximos]

Hello,

I'm trying to distribute a load through an RBE3 element that happens to be on a symmetry plane. Unfortunately I get singularity errors from NX Nastran, bcs the RBE3 element has 3 constraints from the symmetry condition. I eliminate these 3DOF from the dependency dialog, but still get singularity error. Any suggestion would be greatly appreciated!
BR Alexandros

 

[janFEA]

Hello Aleximos,

what kind of solver do you use, SOL 101, SOL 106 etc.?
If you don't use ADINA solvers (SOL 601/701), similar problems with RBE3 can be solved by using of UM sets.
Please check this, it can be a solution for you.


Regards, Jan


With best regards,
Dr. Jan Vojna
Lead Engineer Development

Siemens, s.r.o.

 

[aleximos]

Hello Jan,

thanks for the answer. I'm using NX Nastran solvers and couldn't manage it . I'll just not put the load on the symmetry plane

 

[janFEA]

Aleximos,
NX Nastran uses several solvers. Different solver = different cure
That's why I wanted to know if you use SOL101 or SOL601.
Can you share .dat file?

 

[aleximos]

Right Jan!
I'm trying first with linear static. Any help is greatly appreciated

 

[janFEA]

Hello,
I get it, it is actually very simple - just activate parameter AUTOMPC.

Have fun, Jan

 

[aleximos]

Thanks Jan again! But still didn't manage it. Could you upload the .dat file?

 

[janFEA]

Oooops sorry I already deleted all
But don't worry, it is simply. You have used parameters:

PARAM,PRGPST,YES
PARAM,POST,-1
PARAM,OGEOM,NO
PARAM,AUTOSPC,YES
PARAM,K6ROT,100.
PARAM,GRDPNT,0

So just add PARAM,AUTOMPC,YES (you can whenever in BULK DATA) and run the job again, that's all...
Just try this, it should work.