Stitching imported step files

harryvanlangen

Hi, I import my geometry as a number of ("tightly fitting") step files. When generating a mesh the nodes on the boundaries are duplicated and not always fully aligned. Merging of nodes therefore sometimes fails. Is there a way to force single nodes at boundaries as part of the mesh generation process? Thanks. Harry

Victor

Some options:

• Merge the parts in CAD in advance.
  
• Use bonded contact to join them.
  
• Try Gmsh which seems to be more consistent at keeping same-shaped faces having the same mesh.
  

harryvanlangen

Thanks Victor. The parts have different thicknesses (1 is out) and many contacts (2 is out); so I guess 3 is my only practical option. PS: GMSH consistently crashes. I am running Meeway 8. Should I be aware of compatibility issues? Harry

Victor

I use Gmsh 2.16 and 3.06. Some STEP files make it crash doing a volume mesh but others are OK and surface mesh is more often OK. I'm not sure why.

How does different thicknesses prevent you merging them in CAD?

harryvanlangen

Probably my ignorance on the options to assign thickness. I do that by component. Each Step geometry automatically generates a component so on mesh refinement I don't have to recreate them, whereas a single Step forces me to redefine components every time I refine. Not sure this makes sense? Also, and I sometimes have difficulty controlling orientation of faces on a single Step, which matters to me because of hydrostatic pressure loading.

Victor

I see. Yes, that would save you redefining components every time. I don't have any more suggestions, sorry.

You can reverse shell elements with Mesh tools -> Invert, though it will be lost when you remesh it.

harryvanlangen

Thanks

Sergio

You can import all the steps in Salome and make a union (partition on Salome) of the steps to generate then a conformal mesh.

harryvanlangen

Thanks Sergio. How do you in that case assign different thicknesses to mesh regions, without selecting elements one by one?

Sergio

But do you have well defined (a partition on the faces) each thickness region? In that case can be done also en Salome creating groups of elements by face and then in Mecway assigning a different material/thikness to each group (previously you need to transform to a Mecway part the groups).

harryvanlangen

Sorry Sergio, I may have misunderstood your original advice. What file type do you export from Salome to Mecway?

Sergio

Export as .unv