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Working with topology

Posted by Bonan at November 15. 2012

Hello every body

I face some problems by exporting an .IGES file wich includes a topography shape.

How do I proceed to create correct boundaries that works for bolean operations and for meshing.

Exemple of one problem I met : I export my .iges and then build a shell from it. I repair the shell (sewing etc...) and built a solid. I would like to perfom some bolean operation to it but it always lead to incorrect shapes, and when it work, two faces desapear, the topography face and a side face resulting to impossible repair.

thanks for you help.

Re: Working with topology

Posted by Bonan at November 15. 2012

importing of course sorry

 

Previously Bonan wrote:

Hello every body

I face some problems by exporting an .IGES file wich includes a topography shape.

How do I proceed to create correct boundaries that works for bolean operations and for meshing.

Exemple of one problem I met : I export my .iges and then build a shell from it. I repair the shell (sewing etc...) and built a solid. I would like to perfom some bolean operation to it but it always lead to incorrect shapes, and when it work, two faces desapear, the topography face and a side face resulting to impossible repair.

thanks for you help.

 

 

Re: Working with topology

Posted by William Tougeron at November 15. 2012

Hello, Bonan,

Maybe you could enclose the shape to import and a dump of your study (with [Ctrl] + [D]). Because it seems that your method is good.

William

Re: Working with topology

Posted by Bonan at November 16. 2012

Thank you for your help William

 

I abondonned the idea to perform boleans on my solid. I am trying now to use the body fitting to mesh my untruncated solid. I create a python script usind coordinates and now I am facing a new problem : In trying several configurations it always lead to this kind of error message : 

Cartesian_3D failed on subshape #1 with error COMPERR_ALGO_FAILED "Wrong END (or SOLE) transition of GridLine (...,...) along whatever X,Y or Z: IN

Do you have a method to fix the problem efficiently ?

Thanks for your help

Re: Working with topology

Posted by SMESH expert at November 16. 2012

Hello Cyril Bonan

If you attached (or transfered any other way) your model, your case could be analyzed to see if it is a bug of algorithm.
Meanwhile you can try to decrease tolerance of your model (menu Repare / Limit Tolerance).

Best regards

Edward

 

Re: Working with topology

Posted by Bonan at November 16. 2012

Hello Edward and thanks to you

I can't post my study...

What is the tolerance about? can you explain me please?

Re: Working with topology

Posted by SMESH expert at November 16. 2012

Tolerance is explained in this doc (there is a dedicated chapter) http://docs.salome-platform.org/salome_6_5_0/gui/GEOM/SALOME_BOA_PA.pdf

Varying the tolerance sometimes helps while constructing geometry, and in your case there is a small chance that this could help.

Those errors are emitted when a line of a Cartesian grid traverses the boundary of your model only once (as if your shell is not water -tight) or first it comes out and then comes in. Such issues can be addressed but I have not faced such problems yet to fix them.

Best regards
Edward

Re: Working with topology

Posted by Bonan at November 16. 2012

Thank you SMESH expert.

How do I choose my grid to enclose my domain ? should I let large space each side or the closer to the extremity of my domain?

Re: Working with topology

Posted by SMESH expert at November 16. 2012

Strictly speaking it does not matter. But if you make your grid larger you have a chance to avoid the mentioned errors by shifting the whole grid (at least every node close to face boundary) a little in direction(s) perpendicular the direction reported by an error message.

Regards
Edward

 

Re: Working with topology

Posted by Bonan at November 16. 2012

Edward, can I send you a private message with my domain and scripts ?

Re: Working with topology

Posted by SMESH expert at November 16. 2012

Yes, I've  sent you a message to cyril.bonan(AT)gmail.com.

Edward

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