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NX 8.5 - 2D Mesh bed quality - 3D Swept Mesh Algorithm failed

Creator
Creator

Hello,

 

I am trying to generate a custom 3D mesh on the following geometry. The geometry has some extremely narrow parts which I would like to model in more detail than the rest of the geometry.

LocalRemesh.png

I tried following approach:

Since the geometry is a bored plate, I generated one side 2D cover mesh with the 2D Mesh+paver. I used the 2D local remesh to improve the mesh on the required part and used the 3D Swept Mesh to generate the layered mesh throughout the volume.

 

What happened:

The 3D Swept Mesh failed: "Algorithm failed - the quality of the elements is too poor" When I checked the 2D mesh quality it really showed some failed elements.

ElementQuality.png

So, I have following questions:

  • How can I do local remesh and NOT get this wrong mesh? Or, how can I repair the mesh? I did not find any smooth command to fix the mesh.
  • Is this 2D remesh approach good in this case? Or is there a better one?
  • Can I somehow force the 3D Swept mesher to create the mesh even he thinks the 2D Mesh is “poor quality”?

 

 

Thanks in advance,
Martin.

 

 

4 REPLIES

Re: NX 8.5 - 2D Mesh bed quality - 3D Swept Mesh Algorithm failed

Siemens Phenom Siemens Phenom
Siemens Phenom

Martin,

 

Have you tried defining mesh size controls on the edges? Then turn ON the option to transition the mesh. This could eliminate the need for 2D local remesh and get you to a solid mesh.

 

If the solid mesh is just an extrude of the shells, you could manually extrude the elements into solids. Then you can check the solid element quality. The drawback here is that the solid mesh won't be associative to the geometry.

 

If you want to send me an example, I can take a look.

 

Regards,

Mark 

 

Mark Lamping

Simulation Product Management

Product Engineering Software

 

Siemens Industry Sector

Siemens Product Lifecycle Management Software Inc.

mark.lamping@siemens.com

Re: NX 8.5 - 2D Mesh bed quality - 3D Swept Mesh Algorithm failed

Creator
Creator

Hello,

 

thanks for the quick answer. So I suppose you suggest to use:

MeshControll + (2D Mesh+Transient Size) + 3D Swept Mesh

 

With this I have following result/problem:

WithMeshControll.png

The Transient mesh controll, in the 2D Mesh dialog box, is checked, but there is no value to controll the transient mesh ratio. So, this solution is even worse than the first one.

 

I am attaching model sample for you to experiment on.

 

Re: NX 8.5 - 2D Mesh bed quality - 3D Swept Mesh Algorithm failed

Creator
Creator

For clear understanding....

I used the "Size on edge" mesh controll with overall size 0,05

And I used 2D Mesh generator with paver on, element size 5, allowed triangles and "Transition element size" checkbox checked.

Re: NX 8.5 - 2D Mesh bed quality - 3D Swept Mesh Algorithm failed

Siemens Phenom Siemens Phenom
Siemens Phenom

Martin,

 

Thank you for sharing your data and clarifying how you've tried to mesh the face. I was thinking of using the same type of approach. It's fairing poorly for me too. I succeeded by forcing the transition in the geometry. I split the solid into 3 bodies by offsetting the slot edges into the face. I chose to offset the edges by 0.2mm. 

 

I defined edge densities of 0.05mm on all the slot edges. Then I created a shell mesh on the slot solid body's face using a size of 0.2mm and transition ON. I did the same with the other co-planar faces on the other 2 solids, but used a size of 5mm. After that I generated 3 solid meshes. I was using NX 9 as I don't have NX 8.5 loaded on my machine.

 

The attached files represent the CAD geometry from my 3 solid bodies and the mesh from my 3 swept meshes (parasolid and Nastran bulk data files). 

 

Regards,

Mark