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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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Problem with STL import (Cannot Resolve Domain Relations)

Posted 2011年4月22日 GMT-4 15:15 Version 4.1 3 Replies

Adam Steele
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I was having some strange behavior with this domain relations error and was advised to try update 3. Here is my issue at present:

Just installed 4.1 update 3.

trying to create a geometry by importing some files from a CAD program. I imported one part at a time from .STL files. I have 5 objects and a cylinder surrounding everything.

It seems like some of the objects (1,3,4) will not (individually) form a union with the cylinder and others (2,5) will. 2, 5 and the cylinder will also form a union with each other and the cylinder. (When the repair tolerance is anywhere between 1e-3 and 1e-6) AT a repair tolerance of 1e-7 the objects just look like wireframes after the union

So what is wrong with objects 1,3 and 4? They are all parts of similar size and don't appear to have any crazy surface geometries or anything. Also, the program seems to freeze up for an inordinately long time (several seconds) when trying to make the union when compared with geometries I make in COMSOL.

I have attached my geometry.

(edit: 4:35 for greater clarity in subject)

Attachments:

3 Replies Last Post 2011年4月23日 GMT-4 08:05
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2011年4月22日 GMT-4 17:15
Hi

so long you do not also distribute the stl files, we other out here cannot open correctly your model.

Anyhow, we have probably few options. I suspect that it is related to the stl file format. That is not a true 3D CAD data format, it's for 2D/2.5D and "3D" printing. My advice, use rather a more robust CAD format such as step, or parasolid (you might need the CAD interface)

--
Good luck
Ivar
Hi so long you do not also distribute the stl files, we other out here cannot open correctly your model. Anyhow, we have probably few options. I suspect that it is related to the stl file format. That is not a true 3D CAD data format, it's for 2D/2.5D and "3D" printing. My advice, use rather a more robust CAD format such as step, or parasolid (you might need the CAD interface) -- Good luck Ivar
Adam Steele
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Posted: 1 decade ago 2011年4月22日 GMT-4 17:35
That seems odd, that you need the STL files to open the .mph since I just moved the STL files into a different directory and was still able to open the .mph file just fine.

Maybe you meant that you wanted to examine the .stl files to see if they are in a format COMSOL doesnt like? I have attached them(change their extensions back to .mph). Some other programs, like SimIon, don't seem to have a problem opening them.
That seems odd, that you need the STL files to open the .mph since I just moved the STL files into a different directory and was still able to open the .mph file just fine. Maybe you meant that you wanted to examine the .stl files to see if they are in a format COMSOL doesnt like? I have attached them(change their extensions back to .mph). Some other programs, like SimIon, don't seem to have a problem opening them.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 2011年4月23日 GMT-4 08:05
Hi
I could open it but not change any geometry settings. Obviously COMSOL cannot decompose your stl files if there is more than 1 item. It is most probably linked to the way STL files are assembled. One cannot even convert it and decompose it not measure anything on it.

Try to use a true 3D file format it's essential that COMSOL manges to decompose a volume and identify adjacent boundaries etc. There is a difference between rendering on a 2D screen , and analysing a true 3D geometry

--
Good luck
Ivar
Hi I could open it but not change any geometry settings. Obviously COMSOL cannot decompose your stl files if there is more than 1 item. It is most probably linked to the way STL files are assembled. One cannot even convert it and decompose it not measure anything on it. Try to use a true 3D file format it's essential that COMSOL manges to decompose a volume and identify adjacent boundaries etc. There is a difference between rendering on a 2D screen , and analysing a true 3D geometry -- Good luck Ivar

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