CFD Online Discussion Forums

CFD Online Discussion Forums (
-   ANSYS Meshing & Geometry (
-   -   Pro/Cons of Importing an IGES vs Step file into Workbench (

jonny_b July 29, 2011 13:46

Pro/Cons of Importing an IGES vs Step file into Workbench
Hey guys,

I'm trying to understand the advantages/disadvantages of importing 3D geometry into ANSYS workbench (in particular DesignModeler) as an IGES or STEP file. From my limited knowledge of the file formats they seem to be very similar. Does anybody have any guidance or preference as to which of these two formats they would rather use to import geometry from.


jonny_b August 2, 2011 08:37

So after doing some research I figured I would reply to my own post with my perceptions as to which of these two formats may be better. I noticed a decent amount of views so maybe it can help someone in the future.

After doing some investigation and simple scenarios in DesignModeler and Ansys Mesher, it seems that the two formats don't have to much of difference. The geometry imported into DesignModeler from either an IGES file or STEP file seems to be identical. I did notice that more bodies (surface bodies and volume bodies) are created after an IGES import whereas only a single volume body is generated with a STEP file. At the very least this would imply to me that the STEP import is a bit cleaner from an assembly structure standpoint (one body to deal with versus many surface and volume bodies). In terms of performing CAD type manipulations to the geometry in DesignModeler, both formats seem to behave similarly.

I realize this might be not as informative of a post as one might hope but perhaps it can spawn some educating discussion about the topic.

One last thing to note. I've seen posts that you really would ultimately like to import geometries in other formats (ACIS at the very least). So if you have the your workbench installation configured (and the appropriate license strucutre) to allow you to import direct CAD files from Pro-E, UG, Autodesk products etc., you should do that.

PSYMN August 3, 2011 11:49

Correct. IGES and Step are pretty much worst and second worst, but it is a close race for worst. It is a fundamental flaw of essentially sloppy open format geometry.

Just about anything else you can try will be better. For any commercial users doing real work, the time you save not repairing a bad model will quickly pay off the cost of the CAD or Geometry readers. For Academics, you may already have these CAD readers included in your bundle and just need to output ACIS or Parasolid or perhaps even save the actual CAD file out of your CAD system (instead of IGES).

All times are GMT -4. The time now is 12:04.