I'm lost! Help me meshing this

[flyforever85]

I've for two full days, and I can't obtain a nice quad mesh on the geometry in the picture. The flange is 0.04 in thick. I tried tet elem but due to the thickness of the flange they are too deformed.

Please help!

 

[karachun]

Why not to use free mesh instead of maped. Ouput will be the same.
And delete diagonals to get quad element at corner.

 

[FEA way]

I don’t use Nastran but meshing strategy should be the same in all programs. Try meshing this with square partition around the hole.

 

[nastran_sol_200_web_app]

This is what I would do.
[ol]
[li]Create 8 outer solids and 8 inner solids of the cylinder. Each solid should be separate and the edges must be aligned. See the attached image.[/li]
[li]Mesh the top surfaces with 2D elements as you are doing.[/li]
[li]Sweep the mesh through the thickness to build your 3D HEX elements.[/li]
[li]Perform an equivalence to remove duplicate nodes.[/li]
[/ol]

I suspect the trouble is coming from the inner cylinder solid(s). As I see in your image, the blue edges of the inner solid are not aligning with the edges of the outer solids. As you mesh the surfaces, you probably end up finding the meshes are not lining up.

 

[karachun]

Here is another variant.

 

[cohoman]

You don't say what pre-processing software you are using to make the mesh, but if you were using Patran I would use the Paver or Hybrid option to mesh the top surfaces of that solid with quad elements, then extrude the quad elements down to create hex elements. Then, delete the quad elements (since you won't need them). You should get a useable hex mesh using that approach.

 

[flyforever85]

THank you all for your kind answer, I was able to finally split the geometry but still keep the mesh seed equal for geometries. Yes, I use Patran