NX Advanced Simulation and Surface contact mesh

[Alakin]

Hi all, I created a model with tet10 element, this model has 2 bodies in contact through 2 surfaces. I created a mesh mating condition Free-coincident between the two bodies so that the mesh were coincident. When I try to create the cgap elements between the two surfaces with coincident mesh using the command "Surface contact mesh" it creates the cgap elements but also some rbe3 elements, and i don't undertand what it's doing and why.
Can anybody help me?
Thanks

 

[BlasMolero]

Dear Alakin,
Read carefully this thread where I answered a question related about meshing with CGAP elements in NX AdvSim

http://www.eng-tips.com/viewthread.cfm?qid=371674

If you try to solve a linear static analysis using NX NASTRAN (SOL101), I strongly suggest to define contact in the SIM environment and use "NO PENETRATION" SURFACE-TO-SURFACE CONTACT, is more effcient, simply & modern than using CGAP node-to-node contact elements in the FEM environment.

Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48004 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

Blog de FEMAP & NX Nastran:

http://iberisa.wordpress.com/

 

[Alakin]

Thanks Blas for the quick reply, unfortunately I have to use cgap elements because I also need non-linear elasto-plastic material and I don't have sol 601 license.

In the other discussion you wrote:
Also, revising the mesh I note that RBE3 RIGID elements are included in the FEM model!. In fact, "surface-Contact-mesh" based in node-yo-node CGAP elements is tricky in NX ADVSIM, if the two end nodes of the CGAP elements are not exactly coincident and alligned then NX AdvSim will create in one end a spider based in RBE3 elements to "solve" the problem. If I open the model in FEMAP you can see the spiders used based in RBE3 elements (in white color).

The fact is that the two mesh are perfectly coincident and aligned as I already said and if I click on "Information" of that MMC collection it gives me the list of coincident nodes (2175 pairs). So I don't understand why it creates the RBE3 elements. The only thing I can do is create them in excel form this list of nodes and copy past them in excel but it's not really user friendly and I think is something that the pre-processor should do

 

[BlasMolero]

Dear Alakin,
Well, this is NX AdvSim, is very easy-to-use but things runs this way, if you want "total control" of everything open the NX Nastran model in FEMAP and you can change/create any FEA entity you like. Also, you can import your NX Nastran input deck (*.dat) as well in a new session of NX AdvSim using FILE > IMPORT > SIMULATION, this way you will see "explicitely" the RBE3 elements generated previously, and you can delete anything. But then the mesh & geometry won't be associated ...
Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48004 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

Blog de FEMAP & NX Nastran:

http://iberisa.wordpress.com/