Good Afternoon.
I’m trying to obtain a full extruded hex mesh as homogeneous as possible but there is no way I can control de number of elements per curvature.
Seems the number of elements is attached to the number of sectors used in the geometry of the curves in the original file.
¿Is there any other better approach to get a more uniform regular hex mesh for this particular case?.
Thanks
If you set a very low number of elements per curvature, like 0.01, the element size will not be dominated by the elements per curvature setting but by the global element size setting.
Abaqus can mesh it like this without partitions and local refinements:
Here, you could try adding some partitions since that’s the best way to control the mesh patterns and use Extrude Mesh.
As far as I remember is very hard to have an exact control of the number of elements per edge in Prepomax, but you could mesh your part in Salome. In your CAD make some face spliting to leave four side faces, and then use the Quadrangle Medial Axis projection algorithm to get a smooth and controlled quad mesh. You should analyze if in fact you need those exterior radius or not, because they will take a lot of elements once you extrude along the lenght.
The problem in the .pmx file is, that your edge boundary is not connected. Multiple curves are used for modelling one radius.
Extracting a single face and saving it to .step file then importing to PrePoMax, the geometry is much cleaner. And no partitions are needed for the following mesh.
*** Edit ***
But for a coarser mesh, get rid of all fillets.
Oh, Thanks Matej. I was suspecting something like this. It was always generating the same number of elements per curvature no matter what.
Regarding the extraction :
My first attenmpt was in that direction. I tried to delete all faces from the Step but the front one but I failed. This was the message.
How do you extract one face?. I don’t see that command.
FreeCAD has nice tools for that, I would prepare the geometry there before importing to PrePoMax.
You need a CAD tool for extracting/duplicating/offseting faces.
I have also tried to export to stl from Prepomax and later load it again. Erase faces but the remaining part is solid and not shell ?¿?. Not sure if that could be the reason why it later makes strange thinghs. See image.
Result seems close to provide good results but some nodes fly away.
I will try what you suggest :
Extract a single face outside Prepomax
Save to .step
Thanks to all.
Can Prepomax extrude shells?. Unless I’m missing something the only way I can see now is thicken and offsetting 1/2 the thickness. Is that equivalent or could that approach present some drawback during the analysis?.
I have run again a known problem with solution and GUI is giving me this message which I don’t know how to read .Mesh looks good, all quads/hexa and properly positioned.
Once the results are opened, the resulting mesh is compared to the model mesh. If the meshes are precisely the same, the geometry information (edges, faces) is copied from the model for a nicer visualization. If the meshes are slightly different, this window opens. The reasons for this slight change could be contacts with initial penetration. I am not aware of other cases when this happens (maybe you recreated the mesh).
Can you reproduce this message and share the model?
You can use shell elements. For that, a surface geometry meshed with shell elements is enough.
Plane stress U-shaped member 3D.pmx (3.2 MB)
Extrude mesh is for solid (volume) geoemtries. You select a surface for tri/quad mesh and then the extrusion direction is automatically detected and wedge/hexa mesh is created. Similar for Revolve mesh. If you have a surface (shell) geometry, you should use Shell Gmsh first and then Thicken Shell Mesh.
Right. That’s what I thought. There is no extrude command for shells.
The main drawback with extrude solids is that 2D mesh algorithm 11 Quasi-structured Quad) doesn’t work when aplied to a solid face.
Mybe Matej can find the way to silently extract the face from the solid as shell so extrusion operation could be converted into it’s equivalent Shell meshing + thicken + Offset.
Isn’t Shell Gmsh + Thicken Shell Mesh sufficient in most cases ?
Hopefully yes. That was one of my questions above. I’m not sure if offseting the mesh from the underlaying geometry may cause any unnexpected response.
My first attempt launched a warning message.
