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convert imported *.stl into solid

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I am importing a rather complex geometry into COMSOL from Solid Works. After some tinkering with the import controls, I managed to import the object but I do not think COMSOL recognizes it as a solid. When using the physics, I can only click on edges, not faces.

What do I need to do to 'knit to solid' or make the object into a solid as recognized by COMSOL. Any direction would help a lot.

Should I maybe open it in a different software and convert it into a solid there?


8 Replies Last Post Sep 8, 2017, 1:24 p.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago Oct 22, 2012, 2:55 a.m. EDT
Hi

I mostly use Parasolid, or STEP, as STL is not a true 3D CAD coding, but a layered 2D coding

--
Good luck
Ivar
Hi I mostly use Parasolid, or STEP, as STL is not a true 3D CAD coding, but a layered 2D coding -- Good luck Ivar

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Posted: 1 decade ago Jan 28, 2013, 10:37 p.m. EST
Dear Alexander
What have you used finnaly? I have a 3d surface triangular mesh in a .stl file, but I don't know how to make a solid from it, in order to use it as a geometry for my model.
Dear Alexander What have you used finnaly? I have a 3d surface triangular mesh in a .stl file, but I don't know how to make a solid from it, in order to use it as a geometry for my model.

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Posted: 1 decade ago Feb 4, 2013, 5:57 a.m. EST
I have the same problem as well. I can import the triangular surface mesh in geometry sequence. I can convert this to a solid (mostly when i am lucky) but always fail to combine this object with other geometry objects. Simple the difference or union or other operations fail! Do you have any suggestions?
I have the same problem as well. I can import the triangular surface mesh in geometry sequence. I can convert this to a solid (mostly when i am lucky) but always fail to combine this object with other geometry objects. Simple the difference or union or other operations fail! Do you have any suggestions?

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Posted: 1 decade ago Mar 20, 2013, 12:09 p.m. EDT
Hi!
I managed to find a solution. It is not trivial nor free. We can import the .stl file with +CAD (Simpleware), convert it to a mask and then save/export it as a +ScanIP (simpleware) file. Once in +ScanIP we open the file with the mask and we create a NURBS surface from the mask. We can export the mesh in different formats that Comsol accepts. I tried with .igs extension and it worked.

Some references here:
www.comsol.com/press/news/article/117/
www.comsol.com/products/interfaces/simpleware/

Good luck
Hi! I managed to find a solution. It is not trivial nor free. We can import the .stl file with +CAD (Simpleware), convert it to a mask and then save/export it as a +ScanIP (simpleware) file. Once in +ScanIP we open the file with the mask and we create a NURBS surface from the mask. We can export the mesh in different formats that Comsol accepts. I tried with .igs extension and it worked. Some references here: www.comsol.com/press/news/article/117/ www.comsol.com/products/interfaces/simpleware/ Good luck

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Posted: 9 years ago Jun 30, 2015, 12:36 p.m. EDT
I use the free software Gmsh to convert .stl surfaces into solid meshes.
First create a volume by Modules->Geometry->Elementary entities->Add->Volume
Then mesh solid by Mesh->3D
Export as .bdf and import in COMSOL under mesh option.
I use the free software Gmsh to convert .stl surfaces into solid meshes. First create a volume by Modules->Geometry->Elementary entities->Add->Volume Then mesh solid by Mesh->3D Export as .bdf and import in COMSOL under mesh option.

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Posted: 8 years ago Oct 24, 2015, 7:10 a.m. EDT
Dear Marta,
I've checked your procedure and it worked fine.
Thanks for sharing it here.
Dear Marta, I've checked your procedure and it worked fine. Thanks for sharing it here.

Walter Frei COMSOL Employee

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Posted: 8 years ago Oct 26, 2015, 8:45 a.m. EDT
It is also worth adding to this discussion a brief comment about the upcoming 5.2 release: There will be some significant robustness improvements in STL and mesh import. Not only will these formats import more robustly, you will also be able to perform some further geometric operations on the imported part.
It is also worth adding to this discussion a brief comment about the upcoming 5.2 release: There will be some significant robustness improvements in STL and mesh import. Not only will these formats import more robustly, you will also be able to perform some further geometric operations on the imported part.

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Posted: 7 years ago Sep 8, 2017, 1:24 p.m. EDT
I did this step and imported my *.bdf file into Comsol. but still the error is there and cannot creat solid from it
I did this step and imported my *.bdf file into Comsol. but still the error is there and cannot creat solid from it

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