alternatives to netgen? gmsh?

[kuroshivo]

Hi all

I am one of those who were not able to compile FreeCAD with -DBUILD_FEM_NETGEN=1.
Would it be possible to use Gmsh (http://geuz.org/gmsh/) instead of netgen?

[wmayer]

Would it be possible to use Gmsh (http://geuz.org/gmsh/) instead of netgen?

No. The point is that we don't use netgen directly but by a thin wrapper offered by the SMESH module. However, SMESH doesn't support gmesh and I guess it won't do in the future because gmsh is available under GPL which will cause some license problems.

[kuroshivo]

What about exporting as BREP, calling gmsh and parsing the resulting .msh file?
It would be something similar to the way I understand calculix is used from FreeCAD, wouldn't it?

[psicofil]

A few weeks ago I created a small macro to create mesh inside of freecad with GMSH, because I could never compile NetGen with FreeCAD. Yet is not finished yet but it works ..
I've noticed that FreeCAD not display 2D and 1D meshes or am I wrong?

The original idea is to make a plugin for calculations of structures with Code_Aster which is the software I use.

Here the macro

GMSH Mesh.FCMacro.zip

Not really zip

(4.14 KiB) Downloaded 517 times

Sorry for my bad English.

Regards

[bernd]

Wow, Thanks for sharing the macro.

... I've noticed that FreeCAD not display 2D and 1D meshes or am I wrong?...

Yes that's true FreeCAD does not display 2D or 1D mesh. Have you been able to create a 2D or 1D mesh ? I've been trying to do some time ago but currently I'm on other projects.

[kuroshivo]

nice psicofil! it works like a charm! +1!

just for the record, I think that forking a execing a GPL'ed binary from a LGPL'ed program is legal, isn't it?
BTW, it is a pity that we cannot call a GPL'ed API from a program called Free-something

[wmayer]

just for the record, I think that forking a execing a GPL'ed binary from a LGPL'ed program is legal, isn't it?

http://www.gnu.org/licenses/gpl-faq.htm ... GPLPlugins

[bernd]

Yeah meshing on Linux works like a charm ...

Just encountered a problem. Can someone confirm? Attached a file including a mesh generated by the macro above and an analysis. If I try to write the CalculiX file I get a crash of FreeCAD

Code: Select all

*** Abort *** an exception was raised, but no catch was found.
        ... The exception is:SIGSEGV 'segmentation violation' detected. Address 0

OS: Debian GNU/Linux 8.0 (jessie)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.15.4642 (Git)
Branch: master
Hash: cc7c1d1f44715b4b024d625d36f2a34ea3b50b8c
Python version: 2.7.8
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.7.0

[wmayer]

Just encountered a problem. Can someone confirm? Attached a file including a mesh generated by the macro above and an analysis. If I try to write the CalculiX file I get a crash of FreeCAD

There is a bug in FemMesh::writeABAQUS. The volume has only four elements but it tries to access a fifth element:

Code: Select all

apair.second.push_back(aVol->GetNode(4)->GetID());

[PrzemoF]

What version of gmsh do you use? I have:
$ rpm -qi gmsh
Name : gmsh
Version : 2.8.5
Release : 5.fc21
Architecture: x86_64

and it's crashing badly with the macro with memory corruption error even for a cube.

P.S. Is it possible to rename GMSH Mesh.FCMacro.zip to GMSH Mesh.FCMacro? it's not a zip file.

Edit:
Looks like my problem was related to netgen. Selecting iso or tetgen works fine.