Export IGES - Preserve split edges


I’m preparing an FE analysis model in Rhino, to import into Strand7.
I’ve found the most reliable CAD format for this seems to be IGS. There’s
one aspect of this that is causing problems though, it seems that the
export process removes split edges. I haven’t tried all the provided options,
can any one advise if it’s possible?

The resulting IGES surface has only four vertex.
I’ve been trying primarily the Lusas based settings (as this is a similar use case).
“Use Simple entities when possible” isn’t checked for curves or surfaces.



190816 brep with split edges.3dm (42.5 KB)

190816 test split edge.igs (2.3 KB)

Hi Jon - off hand I do not see a good workaround - @tim - do you have a better idea?
@jonm - it looks like if you split the surface with the lines that make up the split up border (i.e. not joined up into a single curve) , then this survives:

  1. DupBorder
  2. UnTrimBorder
  3. ExtendSrf or scale to make the surface larger than the trims
  4. Explode the border curves from 1 and select them.
  5. Trim off the excess of the surface.
  6. ShrinkTrimmedSrf if needed
  7. Export

Hi Pascal,

Thanks for the reply, that’s really helpful and I’m getting the desired transfer now.
Have a great weekend,