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Repairing a STEP

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Re: Repairing a STEP

Posted by Tobias Holzmann at October 20. 2019

 

Hi all,

for some reason, I could not write into the message area while starting the thread. MIght I ask you a few things about repairing geometries in Salome? Attached, you will find a "easy" geometry which has self-intersections which I cannot resolve. I was playing around with the following:

 

  • Shape Process
  • Sewing
  • Limit Tolerance
  • ...
Furthermore, I removed the faces according to the intersections and wanted to rebuild the faces again (it is a standard procedure I am performing, if I do not get the correct result). However, even if I extract the wires, do some modifications and build new faces, it is still intersecting.

While I have the intersections, I am getting problems while meshing the surface using a triangulation method.
If you are an expert, it would be nice to know how to proceed here.

Any hint is warmly welcomed.
Kind regards,
Tobias

PS: As the file is to large 1.8 MB, I uploaded it to my server: https://holzmann-cfd.de/forums/SolidBasedOnShell.step

Re: Repairing a STEP

Posted by Nejc Jurkovic at October 20. 2019

I have the luxury of having access to Creo at work so I checked the shape with it. There is one round that produces a non-manifold surface and one with just a non-coincident vertex. I removed both surfaces with 'remove' feature and it meshed without problems in SALOME.

I assume you want to do this in free/open source software. I tried with FreeCAD's 'defeature' but it crashed. I was able to remove the problematic surface with SALOME and then wrestle flat surfaces in its place but it still wouldn't mesh. And even if it would, you'd lose the rounds/fillets in the original model.

At the moment I don't have any other ideas (other than just sending you the repaired file :) )

 

Previously Tobias Holzmann wrote:

 

Hi all,

for some reason, I could not write into the message area while starting the thread. MIght I ask you a few things about repairing geometries in Salome? Attached, you will find a "easy" geometry which has self-intersections which I cannot resolve. I was playing around with the following:

 

  • Shape Process
  • Sewing
  • Limit Tolerance
  • ...
Furthermore, I removed the faces according to the intersections and wanted to rebuild the faces again (it is a standard procedure I am performing, if I do not get the correct result). However, even if I extract the wires, do some modifications and build new faces, it is still intersecting.

While I have the intersections, I am getting problems while meshing the surface using a triangulation method.
If you are an expert, it would be nice to know how to proceed here.

Any hint is warmly welcomed.
Kind regards,
Tobias

PS: As the file is to large 1.8 MB, I uploaded it to my server: https://holzmann-cfd.de/forums/SolidBasedOnShell.step

 

Re: Repairing a STEP

Posted by Saint Michael at October 21. 2019
Hi Tobias
 
The attached STEP sets no problem for meshing by NETGEN-1D2D3D .
 
 
St.Michael

Re: Repairing a STEP

Posted by Tobias Holzmann at November 11. 2019

Hi all,

I have a problem writing in this forum. The text-box is sometimes not selectable. Thus, sorry for the last post.

Thanks for posting:

@Saint Michael. I was just interested in the surface meshing but thanks for your comment

@Nejc: Thanks for checking the STEP. You are right, I am working with the free-salome version.

Re: Repairing a STEP

Posted by Damian Berghof at November 15. 2019

Hello Tobias,
I've also investigated your geometry. It's really hard to get-rid of the self-intersections and to heal the geometry with known Free and Open Source Tools like Salome, FreeCAD or Blender. The best would be to do some kind of reverse engineering with NURBS or to build it from 0 step by step and create a parametric module in Salome Shaper or FreeCAD. But that's on other page and some really heavy tasks for the next few years:)
best,
Damian

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