Importing gdsii or dxf files into Elmer

Mesh generators, CAD programs, and other tools
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derek
Posts: 1
Joined: 28 Oct 2009, 17:44

Importing gdsii or dxf files into Elmer

Post by derek » 28 Oct 2009, 17:49

Hi everyone,

I am working on importing some structures into Elmer that are based on gdsii files that were developed with L-Edit for mask drawing and layout design for microfabrication of MEMS devices. It should be possible to convert these into the drawing interchange format (dxf). If anyone has suggestions for the best route to convert these structures into meshs that Elmer can use, I would greatly appreciate it.

Thanks,

Derek

Nobody-86
Posts: 3
Joined: 28 Oct 2009, 15:08

Re: Importing gdsii or dxf files into Elmer

Post by Nobody-86 » 29 Oct 2009, 01:56

Hi,

I dont know gdsii or L-Edit, but maybe it is possible to export to *.IGES, *.IGS, *.STEP or *.STP Files ( theys are all 3D CAD standart files). You can use Salome ( http://www.salome-platform.org/ ) to mesh the geometry and import the mesh as an *.UNV file in Elmer.

btw, are you using Windows or Linux? Salome dont work to 100% in Windows.

Greetings,
Sven

mzenker
Posts: 1741
Joined: 07 Dec 2009, 11:49
Location: Germany

Re: Importing gdsii or dxf files into Elmer

Post by mzenker » 31 Aug 2010, 14:31

If you work on Windows, you can use gmsh (http://www.geuz.org/gmsh) to import STEP, IGES or BREP files and mesh them. The result (.msh) can be imported by Elmer.
Two hints:
1. Make sure that your length units are what you think they are. If they are mm, you have to scale your imported mesh accordingly to get correct numerical results out of the simulation.
2. Beware of double surfaces between adjacent bodies! gmsh leaves them as they are, and Elmer can unify them only if the mesh points are very close. If the mesh is not unified, you do not have electrical and thermal contact through the interface.
@Sven: Do you know if Salome can resolve this kind of problems?

HTH,

Matthias

meniou
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Joined: 21 Oct 2011, 11:23
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Re: Importing gdsii or dxf files into Elmer

Post by meniou » 21 Oct 2011, 11:29

Hello,

I had the same need, and although it seems straightforward with dxf export, stp conversion and meshing in gmsh, it turned out to be *very* much harder. I have now a *very* convoluted way to get from a gds layer to an Elmer simulation. If anyone needs to do the same, I can post it as it is. Else, I will post it once it is reasonable (like something you can put in a script and forget the inner workings).

Anyone interested ?

studioa
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Joined: 23 Jul 2011, 23:39
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Re: Importing gdsii or dxf files into Elmer

Post by studioa » 22 Oct 2011, 04:22

Myself I'm using this path:

1. initial model (I use various applications to generate the BIM = building information modeling, since I'm an architect ...)

2. then save the .dxf out and import into Blender (if any issues, the .dxf can be converted
very well with freeware tools like DraftSight available for mac/win/lin ... I use proprietary tools like AutoCad, but in case you do not have to buy a professional tool, DraftSight can do very well the job)

3. then I export as binary .stl (there are couple very good Blender scripts to export to .stl)

4. then I import in Netgen/NGsolve and mesh

5.finally I save in Elmer format and import the mesh in Elmer.

6. set up the case and run

It is not the perfect path but works very well.

marina
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Joined: 29 Nov 2011, 09:10
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Re: Importing gdsii or dxf files into Elmer

Post by marina » 29 Nov 2011, 09:21

Hi meniou ,

Can you, please, post your "*very* convoluted way to get from a gds layer to an Elmer simulation".

I am trying to use the same method: dxf - Gmsh- Elmer.

M.

meniou
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Joined: 21 Oct 2011, 11:23
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Re: Importing gdsii or dxf files into Elmer

Post by meniou » 10 Apr 2012, 17:16

Sorry for late answer.
This is how I managed to simulate the electrical parameters of a resistive layer on a gds design.
- In Klayout, merge the layer to remove all "polygon" elements, save the layer in its own gds.
- convert to svg using "gds2svg". After download, change "process.txt" to convert only your active layer, and run gds2svg -i input.gds -o output.svg
- open output.svg in inkscape to :
+ unlink clone [shift alt D]
+ ungroup
+ vacuum defs
+ convert to path
Then :
- Import in Blender. Export as stl
- open stl in FreeCAD. Create shape, mesh, with tolerance 0.01. Export STP.
- open STP in gmsh, clean the lines, and mesh.
You should then be good to go with your mesh file.

The inkscape part is scriptable, as is the gds2svg part.

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