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Connect sheet bodys or 2D-meshes that share no edge

Creator
Creator

Hello,

 

 

i have several sheet bodys (see attached screenshot) and try to sew them into one sheet body, to get a connected mesh for my simulation.

 

 

 

 

2019-01-28 14_40_02-NX 12 - Pre_Post.png

 

I have tried following commands:

unite (NX CAD) - not possible for sheet bodys

sew (NX CAD) - just able to sew sheets, that share one edge

glue command (NX Simcenter) - not possible at all for glueing edges of sheets

stitch edge (NX Simcenter) - just able to sew sheets, that share one edge

mesh mating (NX Simcenter) - not able to deal with sheet bodys

 

 

 

 

 

 

 

 

My actual workaround:

I am thickening (with the command "thicken") all sheet bodys in the CAD and use the "mesh mating" command, because it can handle the bodys.

After that i 2D mesh only the needed surfaces.

This is getting pretty complicated in big sheet body assemblies.

 

 

2019-01-28 14_44_18-NX 12 - Pre_Post.png

 

 

 

Maybe you can help me and find a better solution than my actual workaround.

 

 

I am using NX 12.02.

 

 

Best regards,

 

David

6 REPLIES 6

Re: Connect sheet bodys or 2D-meshes that share no edge

Siemens Creator Siemens Creator
Siemens Creator

The attached .pdf has a modeling geometry based approach to sew and mesh the geometry.

Hope this helps.

Re: Connect sheet bodys or 2D-meshes that share no edge

Siemens Creator Siemens Creator
Siemens Creator

Alternatively you can stitch in the FEM.

Again see attached .pdf

 

 

Highlighted

Re: Connect sheet bodys or 2D-meshes that share no edge

Gears Legend Gears Legend
Gears Legend

Are you not able to use Edge-to-Surface and Edge-to-Edge Glue Constraints because of the type of Solution you are running? The image below shows the Glue Force results from a SOL 101 using glue constraints for your geometry.

image.png

Re: Connect sheet bodys or 2D-meshes that share no edge

Creator
Creator

Thanks for your fast replies!

 

 

@SteveBoot:

The stitch edge command works fine for my problem.

I was missing the dropdown menu, where i can set "geometry to stitch: edge to face".

 

 

@JamesD:

The solution works also fine. Unfortuantly NX doesn't provide automatic region search mode for glueing edges to surfaces.

So using it in big assemblys is pretty time consuming.

 

 

 

Best regards,

 

David

Re: Connect sheet bodys or 2D-meshes that share no edge

Gears Legend Gears Legend
Gears Legend

David,

 

You are correct that the lack of an automatic pairing method for edge-to-surface gluing, similar to the auto face pair creation method for surface-to-surface gluing, can make it time consuming as the edge-to-surface sim objects need to be set up manually. We did come up with the method of defining the edge-to-surface sim objects that reduces the number of sim objects that need to be created which not only reduces the time to create but also helps ensure that no edges are missed.

  1. Open the Edge-to-Surface Gluing dialog box
  2. Create a Target Region (i.e., Surface Region) containing all the faces of a single polygon body
  3. Create a Source Region (i.e., Edge Region) of all the edges that are glued to the Surface Region created in Step 2.
  4. Repeat 2&3 till all edge-to-surface glues are defined.

Below are images of the 2 simulation objects that would be created if using glue constraints with the CAD parts from the Geometry idealization Simcenter Pre/Post (version 12) Learning Advantage course (in version 11 the course title was Midsurfaces).

 

 

Regards,

 

James

 

image.pngEdges and Faces for Edge Gluing(1) sim objectimage.pngEdges and Faces for Edge Gluing(2) sim objectimage.pngGlue Force results

Re: Connect sheet bodys or 2D-meshes that share no edge

Phenom
Phenom

Hi,

to make it complete, there is an additional method to connect surface edges with the face of sheet structure:

"1D Connection: Edge to Face connection" with RBE elements

 

2019-02-01_104555.png

 

 

2019-02-01_105018.png

 

 With this method every single grid point of edge will be connected with one RBE2-element via one RBE3-spider element to one shell element of face mesh.


2019-02-01_105349.png

 

This method doesn't need a geometrical modification of polygon bodies like stitching will do and it doesn't need the creation of coincident grid point areas.

 

There are some specific  sources of errors:

- The grid points cant't have more than one RBE2-elements in connection.

- The RBE3-leg nodes should not connect to another RBE2-starting node.

- If the face mesh is coarse, the RBE3 elements become large and the influence on results is also expanded.

- If the edge mesh is coarse, the connection is not uninterrupted.

 

But this is real mesh and it can be defined in FEM / AFM. It's no simulation object like gluing which is in SIM only.

 

Additionally:

Stitching can modify the polygon body in a way that additional stitching attempts don't work and there is no fully undo. Undo only withdraws the creation of stitching objects but the modification of polygon body remains. You can see it, for instance, because stitching can deform the faces or edges of polygon body.

 

Finally:

I guess the best method to connect edges and faces which are not connected in a geometric way is Gluing.

But the more you connect your parts in geometry (before building ipart or fem) the less you will have problems afterwards in FEM or SIM.

 

Best wishes Michael

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