Hexa meshing issue

[[email protected]]

Dear STKO forumers,

I am trying to mesh my SSI model using a hexagonal mesh, however whenever I merge two solids, STKO refuses to mesh the model using structured hex mesh and it switches to tet mesh. I cannot use tet mesh as I am planning to use UPbrick elements for my soil domain. When I use compound to join my solids hex meshing is allowed, however my nodes/edges are not merged in this situation. This shows that something goes wrong during merging or also when using union. I was unable to figure out what though.

STKO prompts the following:
--------------
Warning: 2 faces cannot be meshed with "structured" mesh algorithm
46, 65,
Warning: 1 solids cannot be meshed with "structured" mesh algorithm
0,
Warning: 8 edge seed have been changed for "structured" mesh compatibility
Warning: 1 solids cannot be meshed with "hexahedra" unstructurted mesh algorithm
---------------

From what I see from the model the sub-solid that cannot be meshed using hex mesh is the parallelepiped in the middle of the cylinder below the cylindrical cut-out, in the merged model.

What may be the problem in my geometry? (File attached contains both the compound and the merged models)

If you know, please let me know under what circumstances would STKO not allow for hex meshing for future reference.

Thank you for your time in advance!
Bence

[STKO Team]

Here is the fixed model:

PSI_MESHED.zip

(357.93 KiB) Downloaded 304 times

I am trying to mesh my SSI model using a hexagonal mesh, however whenever I merge two solids, STKO refuses to mesh the model using structured hex mesh and it switches to tet mesh.

It happens because some of the base faces have 5 sides! faces mush have 4 sides, and volumes must have 6 sides for hexa meshing.
When you were drawing your line sketch at the base, you should have included an extra cross in the middle

ssi_waring.png (35.04 KiB) Viewed 3950 times

When you have your sketch ready, you can use PlanarFace to get a shell out of it.
Then you can draw a polyline (wire) made of 2 edges, each with the required length such that the mid-face is at the Z-level of the soil volumes you want to remove. This is necessary to obtain inner faces (in your previous model the outer faces were extruded in 1 segment, but merged with the inner ones (2 segments in the Z direction) would create non-6-sided volumes.
With these, you can use the Sweep command, which is an extrusion along a spine:

ssi_sweep.png (80.42 KiB) Viewed 3950 times

Finally, you can go in solid-only subselection, select the volumes you want to remove, and press Delete.

ssi_rem.png (156.66 KiB) Viewed 3950 times

[[email protected]]

Thank you very much for the help and the explanation!

[STKO Team]

You're welcome! Good luck with your model