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Use STL surface in HEXABLOCK

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Use STL surface in HEXABLOCK

Posted by Martin at January 11. 2013

Dear all:

 

I need to mesh the volume in between two STL surfaces with hexahedrons (see surfaces.png). Do I have a chance to get it done with HEXABLOCK? The documentation talks about STEP, IGES or BREP geometries… Thanks for any comment/advice on that!

 

Martin

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Re: Use STL surface in HEXABLOCK

Posted by Saint Michael at January 11. 2013

Hi Martin

In SALOME, there is no means intended to solving such a task. HEXABLOCK will help you neither.

But this task is not absolutely unsolvable. It's possible to write a Python script which should do this way:

1) Close the gap between boundaries of the stl surfaces with a geometrical face. For this: make 2 geom wires from free edges of surfaces, make a geom face on this wires.
2) Mesh this new face with triangles.
3) Unite stl surfaces with the mesh on face into one 2D mesh shell.
4) Mesh this shell with tetrahedrons.
5) Split each tetrahedron into 4 hexahedra.

I would take 4 hours maximum to write such a script. I only suspect if stl boundaries lie in one plane, if not, then the closing face can be strongly not-planar.

St.Michael

Re: Use STL surface in HEXABLOCK

Posted by Saint Michael at January 11. 2013

I would take 4 hours maximum to write such a script.

I even think it would take much less time. I feel appetite to write such a script. Do you need it?

But the result hexahedral mesh would be of very poor quality, corresponding to poor quality of the initial stl triangulation.

St.Michael

Re: Use STL surface in HEXABLOCK

Posted by Martin at January 12. 2013

Hi St.Michael,

 

Thanks for offering your help. Unfortunately, I need high quality hexahedrons, for further processing in a FE code.

 

For the moment, in my group we're using TrueGrid, which does a pretty good job (see image; it uses the same method as HexaBlock, i.e. projecting a topological mesh on some geometrical surfaces), and works with STL surfaces, but is not open source (so any development does not benefit the community/the people who leaves the group) and not free (so we spend a lot of precious money on that). That's why I'm looking for alternatives.

 

Thanks anyway!

 

MArtin

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