Importing format (Help!)
 

I realise that CFX allows quite a number of CAD formats to be imported to Build. I wonder if there's any difference between these formats? E.g. will importing step or sat file be better than importing iges file?

Another issue: Has anyone ever imported the mesh generated by Fluent Gambit to Build before? Will there be a problem if you do so?

Thanks in advance for giving me advice.

Re: Importing format (Help!)
 

Hi Dany,

I'm no expert on CAD import, but here's my experience:

1) IGES is just an approximation to the geometry. In simple geometries (ie straight lines, circles etc) IGES works very well, but for complex geometries with compound curvature IGES causes surfaces edges not to match and other nasty stuff. It is very sensitive to the mobel global tolerance.

2) Parasolid is an exact representation of the geometry (if it comes from a parasolid based CAD system!). However not all parasolid is the same, and you will notice that some CAD systems import better into Build than others. You will still need to do some clean-up work on complex geometries. It has some sensitivity to the global tolerance.

3) STEP and SAT files are alternatives, but I had problems getting the ACIS-SAT license working for me (but I found the parasolid license which comes with it worked OK for me so it was OK). I have no experience with the quality of geometry from these methods.

4) You would think the CAD-specific formats (eg UG, ProE etc) would be the best. However, as most of these CAD systems use parasolid as the basic geometry description I cannot see how these would be much better than parasolid, but I've never tried them.

5) There is basic geometry representation in the Patran Neutral format, but I think it can only handle flat surfaces and simple circles and the like. It will not include any surfaces more complex than that. The main of this format is to import the mesh rather than the geometry.

Has anybody else got experience here, especially points 3) and 4)? If you are dealing with complex geometries, you will be spending a significant proportion of your time fixing geometry problems so Build can use it, so this is an important issue.

Regards, Glenn Horrocks