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Hello Yang Gao

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This seems like a serious deficiency in COMSOL's base product, and one which I still do not fully understand given the online documentation about the CAD Import module.

First, it is called the CAD *Import* module, but it obviously helps to export as well. Just a point of clarification.

Second, it talks about "linking" to external programs such as AutoCad. Does that mean I need AutoCad for the module to work, or will it generate a DXF without AutoCad?

Third, this seems like a very, very basic feature to require an add-on. Who wants to build a model in COMSOL and then not have the ability to do anything with it? Machine shops don't use COMSOL. I need a DXF file or something. But I can't export my model in a format that is readable by anyone else without buying another COMSOL add-on?

This comes as a big surprise to me. It seems akin to having to pay extra for getting Microsoft Word to save as a text file. Some basic export like DXF should be included. OK, don't include the Live Link features. Don't include the defeaturing tools. Don't include the interactive repair. I'm not saying there isn't a place for the CAD Import Module.

But basic file compatabilty with other industry-standard programs? Don't most software packages do that by default?

I hope the developers will consider this feedback.

Hi

I agree exchange is important, but not that important for everyone around.

Normally COMSOL CAD geometry is for FEM use and not for mechanical drawing use. Several other FEM programmes I know about do not even have a CAD feature internally. Any how, the CAD design I get from my designers, have to be defeatured and "split" to improve meshing and FEM building

The LiveLink for SW I use allows me to run a SolidWorks model and update it dynamically by linking COMSOL to Solidworks by having both running (but you can also "just" import a CAD SolidWorks or parasolid File) respectively for the other LiveLink products.

Dxf can only be read (but not exported from my knowledge), at least now 3D dxf is read in and the "z" component ignored in 2D.

Indeed the binary COMSOl geometrical format is not documented, and I suspect it changes between versions

You cannot get everything, but you have got, with COSMOL, the most advanced multiphysics programme I have ever encountered, and its really fun to use it, far more powerfull than the older well established FEM softwares I have used over the last 25+ years

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Good luck
Ivar

Dear Ivar,
I'm completely new to COMSOL. My boss asked me to model some stuff - I'm not a modeler- so I'm trying to learn how to use this program. So I drew my sketch in 2D AutoCad, but when I try to import it tells me that there is a compatibility issue and that I need to use the 'import module' in AutoCad? I have been unable to verify if that actually exists. I also have Solid Works, Corel, ProE. If this is a significant draw back can you suggest a better software to use with COMSOL?

Kind regards,
Gerson

Hi

there is also a version issue, in v3.5a of COMSOL (if I remeber right) you can only import 2D autocad DXF files into a 2D geometry. Many CAD programmes generate 3D DXF format, this is not acceped by v3.5, you need COMSOL v4 for that.

If you are in 3D you need to import 3D file formats, depending on the CAD import module you have purchased you can choose between Pro-E or STEP, Parasolid or SolidWorks or ... see the list on COMSOL's main site (I'm using Parasolid or now directly Solidworks, but still DXF translated files in 2D.

Now for most simulations, the CAD module of COMSOL does fully the job, it's that these are geoemtrical objects tailored for FEM simulations, not for mechanical design and manufacturing with dimension written out etc, or a lot of small details such as fillets champfer, bores, threads etc (still several exist in 2D) that are not norally used in FEM analysis.

Therefore if you start with COMSOL, I can only suggest to start "simple" in 2D and then use the internal CAD to begin with,if you have translations and import issues, that should do for starting up.

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Good luck
Ivar

I believe that the issue is to not charge the COMSOL customer for things they don't need. For all the CAD products supported (Solidworks, Pro-E, Autodesk, etc.) COMSOL has to pay those companies who provide the CAD software for the rights to be able to import their proprietary files. That is all lumped now in the CAD import module. If you don't purchase the CAD import module, then you can only import those formats that are "open sourced", i.e., don't cost anything to COMSOL. If all you need to do is import, that CAD import module is all you need. The "live link" also provides a 2-way communication on both ends COMSOL<->CAD so that the analyst also becomes the designer. This is a powerful feature, but also is not needed by everyone, hence, is provided as an addon since COMSOL also must pay the CAD company for that additional ability to import<->export.

What would be cool is to convince the CAD companies to allow to import COMSOL binary model files. I think that is what you are asking for. So, I think this is not the fault of COMSOL.

Hi

The economical side is, indeed an as important issue, as the quality of the representation of the different CAD formats.

I would love to see COMSOL keep a price compatible to make it the every physicist and engineers tool, and not evolve as other, older tools, as the richest, highly specialist, privilege

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Good luck
Ivar