Problem with meshing, help.

[vmajor]

Hi,

I have been trying, and failing for the past several weeks to generate a mesh with Z88Aurora.

I need to do FEA on a bicycle frame. The current best method for doing this is as follows:

1. export IGES from Pro/E (Creo)
2. Load it into Rhino 3D to clean up the otherwise unusable IGES file (random elements, curves, unterminated lines etc,)
3. Export a clean STL
4. Repair the STL using Netgen STL Doctor, Netfabb and MeshLab - and fail. I still end up with an STL with few invalid triangle orientations and other faults that Netgen cannot deal with - standalone 5.1 or the one that runs inside Z88Aurora.
5. Import the STL into Z88Aurora and attempt to mesh this with Netgen and fail, attempt to mesh with Tetgen and hang at 100% core utilisation.

Alternatively, importing STP likewise fails, with a GEOCON error...something about a missing symbol.

I can obtain a mesh with Gmsh and save it as a .msh file but there is no way that I can see to import this mesh into Z88 and set up the simulation.

Thus please help:

1) advise me on the best or correct way to import actual physical 3D designs, not idealized ones into Z88Aurora

or

2) let me know if it is possible to get Z88Aurora to accept a Gmsh .msh file as that mesh looks pretty good upon visual inspection.

I also attempted to work with Elmer as I can import the Gmsh mesh, but setting up a problem with Elmer requires far too much knowledge that I lack.

Thanks,

Victor

[mifris]

Hello vmajor,

first of all, have you also tried to export an *.stl- or *.stp-file out of ProE? Especially for *.stl-files you can change the settings for export. On the other side, there is a small trick to import a gmesh mesh into Z88Aurora. In gmesh there is the possibillity to export nastran files, but as a *.bdf-file. When you save the model, try to change the ending from *.bdf to *.nas manually and the save the model!
Hope that works.

Best regards,

M. Frisch

[vmajor]

Thank you for your reply! Sorry I did not see it sooner. I thought I subscribed to email notifications, but evidently I hadn't.

STL files fail to generate due to some geometry error. I tried to repair the surface geometry in Creo but I am unable to do so without recreating the model...

Step files export, but they are flawed. I can repaid them somewhat in Netgen and I managed to obtain a mesh, but it appears to be a surface mesh not a volume mesh despite the .vol extension.

Gmsh did mesh some variants of my geometry files, but the results were always surface meshes thus exporting them as Abacus files did not accomplish much as I could not import them into z88 Aurora even after renaming them. I will try this again as that seems to be the likeliest path to success at this point.

V.

[mifris]

Hello vmajor,

it is very important to export only a volume and not surfaces at Creo! If you want to export as *.stp, please check this. Usually a box appers, where you can select it.
After exporting as a "volume" *.stp-file, you can import it into the Netgen GUI. After meshing there, you have to change the export filytype to the abaqus filetyp (file > export filytype > Abaqus). After this, you can export the mesh and import it in Z88Aurora.
I hope, this time it will work.

Best reagrds

M. Frisch

[oringen1]

Hallo M. Frisch,

Sie scheinen sich mit dem Übertragen von GMSH zu Z88 Aurora auszukennen (?). Und zwar habe ich vor ein Volumenmodell, dessen Oberfläche ich mit 2D-Netzen versehen habe in Z88 Aurora zu importieren. Dann würde ich gerne im Aurora das 2D-Netz als Basis für die "innere Verntzung" nehmen, ohne, dass das äußere 2D-Netz sich verändert.

Ich hoffe, dass Sie mir sagen können, welche "Mesh-Optionen" ich im GMSH einstellen muss um dieses Vorhaben erfolgreich umzusetzen.

Vielen Dank
Matti

PS: Als Exportdatei hatte ich bisher *.stl verwendet und würde das auch gerne beibehalten.

[mifris]

Hallo oringen1,

ganz so gut kenne ich mich leider nicht aus. Für mich stellt sich die Frage, warum wollen Sie ein Volumenbauteil erst 2D vernetzen und dann anhand dessen eine 3D-Struktur erstellen? Warum also nicht gleich 3D vernetzen?

Viele Grüße,

M. Frisch

[oringen1]

Halle M Frisch,

die Frage ist berechtigt. Ich habe selbstverständlich erst versucht im GMSH eine 3D-Vernetzung zu realisieren, allerdings gab es ann im Aurora Probleme.

Inzwischen habe ich das Problem allerdings zufriedenstellend gelöst.

Dennoch vielen Dank für die Hilfe.

Matti

[mifris]

Hallo Matti,

schön das sie das "kleine" Problem lösen konnten.

Viele Grüße,
M. Frisch