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Create RBE2 connected to elements two rows deep around a hole

Valued Contributor
Valued Contributor

I'm prepping a model for analaysis in MSC Nastran. Our best practice for mating flange holes is to create an RBE2 at the center of the hole connected to the elements surrounding the hole two rows deep. If I use Point to Edge, it creates a wagon wheel from the center of the circle to the edge (makes sense based on the name). If I split my face with a circle surrounding the whole and use Point to Face, it only connects the center node to the outer ring of nodes. (Update: for some reason, it behaved the way I wanted it to once and selected the inside circle of nodes as well as the outside circle. I can't get it to do it again though.)

 

Any suggestions on how to do this without having to manually select each node?

9 REPLIES

Re: Create RBE2 connected to elements two rows deep around a hole

Siemens Genius Siemens Genius
Siemens Genius

Hi

 

The Point to Face method you described should work.  Sometimes it can be hard to tell if the inner row of nodes has connected correctly since the RBE2 "legs" are colinear for the inner and outer rows of nodes.  Are you sure it's not just this graphical problem?

 

In SC 12, we introduced Universal Connections which may be useful to you depending on the end application.  However, they are only officially supported for NX Nastran and not MSC.  Therefore you would have to be careful that the NXN deck you created was also compatible with MSCN.

 

Regards

Joe

Re: Create RBE2 connected to elements two rows deep around a hole

Siemens Phenom Siemens Phenom
Siemens Phenom

In your description, you say that for the point to face method, you selected the outer edge or the inner and outer edge.  If you are using point to face, the selection filter should have been set to only allow face selection , not edges.

 

Make sure you are using the correct method and that you are selecting the correct objects (i.e. faces, not edges). If face(s) are selected, the RBE should be distributed to all nodes related to those face(s).

Re: Create RBE2 connected to elements two rows deep around a hole

Valued Contributor
Valued Contributor

@JimB wrote:

In your description, you say that for the point to face method, you selected the outer edge or the inner and outer edge. 



@JimB 

When using Point to Face, I'm selecting the face. It only allows face selection.

Re: Create RBE2 connected to elements two rows deep around a hole

Valued Contributor
Valued Contributor

@JoeLuxmoore wrote:

The Point to Face method you described should work.  Sometimes it can be hard to tell if the inner row of nodes has connected correctly since the RBE2 "legs" are colinear for the inner and outer rows of nodes.  Are you sure it's not just this graphical problem?

 


It's definitely not a graphical issue. I picked a hole to practice on where the grid isn't perpendicular to the hole for this reason. I don't know if Universal Connections is a viable option--it sounds like probably not for MSCN--but I'll check it out.

 

I tried doing Point to Edge and selecting the edge of the hole as well as the edge of the surrounding circle, but that did the same thing--only connected to the outer ring.

Re: Create RBE2 connected to elements two rows deep around a hole

Valued Contributor
Valued Contributor

Here are a couple of pics to demonstrate.

RBE2a.pngRBE2b.png

Re: Create RBE2 connected to elements two rows deep around a hole

Siemens Phenom Siemens Phenom
Siemens Phenom

This must be something model specific. The best course of action would be to open a case with GTAC and have someone take a look at it.

 

Re: Create RBE2 connected to elements two rows deep around a hole

Valued Contributor
Valued Contributor

OK, I figured out how to get it to consistently work correctly. If I click on the point in the center or use the inner circle to define the center point, it doesn't work correctly. However, both Point to Face and Point to Edge (selecting the inner and outer edge) work correctly if I use the outer edge to define the center point.

 

Thanks for your responses.

Re: Create RBE2 connected to elements two rows deep around a hole

Siemens Genius Siemens Genius
Siemens Genius

It's good that you found a solution, but I still think you should log this with GTAC as per Jim's suggestion.  The selection method to get the hole center shouldn't influence the output.

 

Regards

Joe

Re: Create RBE2 connected to elements two rows deep around a hole

Valued Contributor
Valued Contributor

Unfortunately it does appear to be part specific and I can't send GTAC the part I'm working on. I creating a simple demo part but couldn't reproduce the issue.

 

I'll see if I can trim off a piece of my model and reproduce it with that.