[Gmsh] mesh problem

Sat Dec 19 18:48:12 CET 2009

Hello David.

The CAD is ProE but i haven't the original file. I'm trying to clean by 
SALOME but i always get error message. thank you for the info about 
refining the mesh.

regards,
Stefano

David Colignon wrote:
> Hi Stefano,
>
> which CAD software do you use to create your geometry ?
>
> I strongly suggest you to export your geometry in the STEP format 
> instead of the IGES format
>
> Concerning your 2D mesh, as you have seen by Checking Tools -> Options 
> -> Mesh -> Visibility -> Surface Faces , some surfaces are partially 
> superposed and cross each other. You can partially solve this problem 
> by refining the mesh , setting the Tools -> Options -> Mesh -> General 
> -> Element Size Factor to 0.1 or less ...
>
> But I think that your geometry is still not clean enough, there are 
> still some errors and warning messages during the 1D and 2D meshing
>
> Regards,
>
> Dave
>
> -- 
> David Colignon, Ph.D.
> Collaborateur Logistique du F.R.S.-FNRS
> CÉCI - Consortium des Équipements de Calcul Intensif
> ACE - Applied & Computational Electromagnetics
> Institut Montefiore B28
> Université de Liège
> 4000 Liège - BELGIQUE
> Tél: +32 (0)4 366 37 32
> Fax: +32 (0)4 366 29 10
> WWW:    http://hpc.montefiore.ulg.ac.be/
> Agenda: 
> http://www.google.com/calendar/embed?src=david.colignon%40gmail.com
>
> On 18/12/09 23:57, stefano zinna wrote:
>> Dear Dave.
>>
>> I cleaned the iges file
>> (https://download.yousendit.com/Z01PcXlsaTFTSUNGa1E9PQ) and generate a
>> surface mesh(https://download.yousendit.com/Z01PcXlnaFJ6RS9IRGc9PQ). The
>> mesh has some problem because there are some intersected surfaces that
>> you can see in the mesh.
>> This is due to the geometry tolerance. What do you think? How can i
>> solve this problem?
>>
>> thanks again for your kind reply.
>>
>> Stefano
>>
>>
>>
>> David Colignon wrote:
>>> If you just open your step file with Gmsh, you can see that there are
>>> some warnings and some errors:
>>>
>>> ...
>>> ...
>>> Info : removing degenerated edge 0
>>> Info : removing degenerated edge 0
>>> Info : - fixing wire gaps
>>> Info : some 2D gaps fixed
>>> Info : some 3D gaps fixed
>>> Info : failed to fix some 2D gaps
>>> Info : failed to fix some 3D gaps
>>> Info : - fixing spot and strip faces
>>> Warning : OCC STL triangulation failed
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Warning : OCC STL triangulation failed
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> Info : OCC Region 1 - New Shell
>>> Info : OCC Region 1 with 2001 faces
>>> Info : Read '/Users/colignon/Desktop/newfile.stp'
>>>
>>>
>>> but they are perhaps not "blocking".
>>> In Tools -> Options -> Geometry -> General , Gmsh has some *basic* and
>>> *experimental* reparation features. You can increase the Tolerance, ...
>>> But you should check and clean your geometry in your CAD software. For
>>> example, with Tools -> Visibility, and by displaying the surfaces with
>>> "ALT+s" you can see that for some reason Gmsh cannot display properly
>>> surface 903
>>>
>>> If you use the command line to try to mesh your geometry in 2D, you
>>> will get much more messages which could help you to find the problems
>>> in your geometry (note that Gmsh crashes before the end)
>>>
>>> ace35:~/Desktop > gmsh newfile.stp -2
>>>
>>> Info : Running '/Applications/Gmsh.app/Contents/Resources/bin/gmsh
>>> newfile.stp -2'
>>> Info : Started on Fri Dec 18 10:32:01 2009
>>> Info : Reading 'newfile.stp'
>>> *** Error on Record 4039 (on 440531 -> 0 % in File) *** Ident #2022
>>> Complex Type incorrect : SOLID_ANGLE_UNIT / SI_UNIT ...
>>> *** Error on Record 27742 (on 440531 -> 6 % in File) *** Ident #9776
>>> Complex Type incorrect : RATIONAL_B_SPLINE_SURFACE / BOUNDED_SURFACE 
>>> ...
>>> *** Error on Record 27744 (on 440531 -> 6 % in File) *** Ident #9776
>>> Complex Type incorrect : REPRESENTATION_ITEM /
>>> GEOMETRIC_REPRESENTATION_ITEM ...
>>> *** Error on Record 37721 (on 440531 -> 8 % in File) *** Ident #12125
>>> Complex Type incorrect : NAMED_UNIT / LENGTH_UNIT ...
>>> *** Error on Record 340757 (on 440531 -> 77 % in File) *** Ident 
>>> #171717
>>> Complex Type incorrect : RATIONAL_B_SPLINE_CURVE / BOUNDED_CURVE ...
>>> *** Error on Record 340759 (on 440531 -> 77 % in File) *** Ident 
>>> #171717
>>> Complex Type incorrect : REPRESENTATION_ITEM /
>>> GEOMETRIC_REPRESENTATION_ITEM ...
>>> *** Error on Record 340760 (on 440531 -> 77 % in File) *** Ident 
>>> #171717
>>> Complex Type incorrect : GEOMETRIC_REPRESENTATION_ITEM / CURVE ...
>>> *** Error on Record 341398 (on 440531 -> 77 % in File) *** Ident 
>>> #172039
>>> Complex Type incorrect : RATIONAL_B_SPLINE_CURVE / BOUNDED_CURVE ...
>>> *** Error on Record 341400 (on 440531 -> 77 % in File) *** Ident 
>>> #172039
>>> Complex Type incorrect : REPRESENTATION_ITEM /
>>> GEOMETRIC_REPRESENTATION_ITEM ...
>>> *** Error on Record 341401 (on 440531 -> 77 % in File) *** Ident 
>>> #172039
>>> Complex Type incorrect : GEOMETRIC_REPRESENTATION_ITEM / CURVE ...
>>> *** Error on Record 348024 (on 440531 -> 79 % in File) *** Ident 
>>> #174944
>>> Complex Type incorrect : RATIONAL_B_SPLINE_CURVE / BOUNDED_CURVE ...
>>> *** Error on Record 348026 (on 440531 -> 79 % in File) *** Ident 
>>> #174944
>>> Complex Type incorrect : REPRESENTATION_ITEM /
>>> GEOMETRIC_REPRESENTATION_ITEM ...
>>> *** Error on Record 348027 (on 440531 -> 79 % in File) *** Ident 
>>> #174944
>>> Complex Type incorrect : GEOMETRIC_REPRESENTATION_ITEM / CURVE ...
>>> *** Error on Record 349696 (on 440531 -> 79 % in File) *** Ident 
>>> #175652
>>> Complex Type incorrect : RATIONAL_B_SPLINE_CURVE / BOUNDED_CURVE ...
>>> *** Error on Record 349698 (on 440531 -> 79 % in File) *** Ident 
>>> #175652
>>> Complex Type incorrect : REPRESENTATION_ITEM /
>>> GEOMETRIC_REPRESENTATION_ITEM ...
>>> *** Error on Record 349699 (on 440531 -> 79 % in File) *** Ident 
>>> #175652
>>> Complex Type incorrect : GEOMETRIC_REPRESENTATION_ITEM / CURVE ...
>>> Info : Healing geometry (tolerance=1e-06)
>>> Info : - fixing small edges
>>> Info : removing degenerated edge 0
>>> ...
>>> ...
>>> Info : removing degenerated edge 0
>>> Info : - fixing wire gaps
>>> Info : some 2D gaps fixed
>>> Info : some 3D gaps fixed
>>> Info : failed to fix some 2D gaps
>>> Info : failed to fix some 3D gaps
>>> Info : - fixing spot and strip faces
>>> Error : Something wrong in edge loop
>>> Error : Something wrong in edge loop
>>> ...
>>> ...
>>> Error : Something wrong in edge loop
>>> Info : OCC Region 1 - New Shell
>>> Info : OCC Region 1 with 2001 faces
>>> Info : Read 'newfile.stp'
>>> Info : Meshing 1D...
>>> Info : Meshing curve 1 (BSpline)
>>> ...
>>> ...
>>> ...
>>> Info : Meshing curve 603 (BSpline)
>>>
>>> Info : Meshing curve 604 (Unknown)
>>>
>>> Info : Meshing curve 605 (BSpline)
>>>
>>> Info : Meshing curve 725 (Unknown)
>>>
>>> Info : Meshing curve 741 (Unknown)
>>>
>>> Info : Meshing curve 760 (Unknown)
>>> Info : Meshing surface 100 (BSpline surface, MeshAdapt)
>>> Info : Meshing surface 101 (Unknown, MeshAdapt)
>>> Info : Meshing surface 102 (Unknown, MeshAdapt)
>>> Info : Meshing surface 103 (Unknown, MeshAdapt)
>>> Info : Meshing surface 104 (BSpline surface, MeshAdapt)
>>> Warning : :-( There are 6 intersections in the 1D mesh (curves 501 448
>>> 495 502 447 454)
>>> Warning : 8-| Gmsh splits those edges and tries again
>>> Warning : :-( There are 2 intersections in the 1D mesh (curves 447 454)
>>> Warning : 8-| Gmsh splits those edges and tries again
>>> Warning : :-) Gmsh was able to recover all edges after 2 iterations
>>> Info : Meshing surface 105 (Plane, MeshAdapt)
>>>
>>> Info : Meshing surface 210 (BSpline surface, MeshAdapt)
>>> Warning : :-( There are 3 intersections in the 1D mesh (curves 890 892
>>> 894)
>>> Warning : 8-| Gmsh splits those edges and tries again
>>> Warning : :-( There are 3 intersections in the 1D mesh (curves 890 894
>>> 892)
>>> Warning : 8-| Gmsh splits those edges and tries again
>>> Warning : :-( There are 3 intersections in the 1D mesh (curves 890 892
>>> 894)
>>> Warning : 8-| Gmsh splits those edges and tries again
>>> Warning : :-( There are 2 intersections in the 1D mesh (curves 892 890)
>>> Warning : 8-| Gmsh splits those edges and tries again
>>> Warning : :-) Gmsh was able to recover all edges after 4 iterations
>>> Info : Meshing surface 211 (BSpline surface, MeshAdapt)
>>>
>>> Info : Meshing surface 274 (Plane, MeshAdapt)
>>> Warning : :-( There are 6 intersections in the 1D mesh (curves 1195
>>> 1195 1196 1196 1181 1182)
>>> Warning : 8-| Gmsh splits those edges and tries again
>>> Info : Meshing surface 275 (BSpline surface, MeshAdapt)
>>>
>>> Info : Meshing surface 336 (BSpline surface, MeshAdapt)
>>> Warning : :-( There are 3 intersections in the 1D mesh (curves 1428
>>> 1429 1438)
>>> Warning : 8-| Gmsh splits those edges and tries again
>>> Warning : :-( There are 3 intersections in the 1D mesh (curves 1429
>>> 1429 1437)
>>> Warning : 8-| Gmsh splits those edges and tries again
>>> Warning : :-) Gmsh was able to recover all edges after 2 iterations
>>> Info : Meshing surface 337 (BSpline surface, MeshAdapt)
>>>
>>> Info : Meshing surface 348 (Plane, MeshAdapt)
>>> Warning : :-( There are 5 intersections in the 1D mesh (curves 1213
>>> 1216 1216 1479 1479)
>>> Warning : 8-| Gmsh splits those edges and tries again
>>> Info : Meshing surface 349 (BSpline surface, MeshAdapt)
>>>
>>>
>>> Dave
>>>
>>>
>>>
>>>
>>> On 18/12/09 09:52, stefano zinna wrote:
>>>> Dear David.
>>>>
>>>> Thank you for the fast reply. I made a routine to avoid double 
>>>> lines so
>>>> i think this isn't the problem.
>>>> I have the original step file
>>>> (https://download.yousendit.com/Z01PSkhYcVhuSlIzZUE9PQ). Can you 
>>>> explain
>>>> which steps are better to generate the mesh?
>>>>
>>>> kind regards,
>>>> Stefano
>>>>
>>>> David Colignon wrote:
>>>>>
>>>>> On 17/12/09 18:36, stefano zinna wrote:
>>>>>> Dear Sirs.
>>>>>>
>>>>>> I converted a .stl file into .geo
>>>>>> (https://download.yousendit.com/Z01NSU5OOW5samQzZUE9PQ) for gmsh.
>>>>>
>>>>> Hi Stefano,
>>>>>
>>>>> very nice geometry !
>>>>>
>>>>> Are you *sure* that each line shared by two triangles is only defined
>>>>> once ? (it seems to be the case...)
>>>>>
>>>>> I'm
>>>>>> able to generate the surface mesh but it is not able to recognize 
>>>>>> the
>>>>>> volume. Is it a problem in the file or it depends on the 
>>>>>> complexity of
>>>>>> the geometry?
>>>>>
>>>>>
>>>>> When you try to create the volume with the GUI and you click on a
>>>>> first surface, you can see that almost all the surfaces are then
>>>>> selected and change color to red. But the GUI keep asking to select
>>>>> volume boundary to fully close the volume. Due to the complexity of
>>>>> the geometry, it is very difficult to detect with the eye by zooming
>>>>> on every part of the geometry if some surfaces are missing, so I
>>>>> cannot see there is a real problem in the geometry or if some 
>>>>> surfaces
>>>>> are left unselected...
>>>>>
>>>>> Converting your CAD file to the STL format and then converting it to
>>>>> .geo is not the best solution. Do you have access to the original CAD
>>>>> file ? Can you try to export it to the STEP format instead ?
>>>>>
>>>>> Regards,
>>>>>
>>>>> Dave
>>>>>
>>>>
>>>
>>
>
>