Wich version for FEM shell development?

Having trouble installing or compiling FreeCAD? Get help here.
User avatar
Groguigui
Posts: 8
Joined: Thu Mar 09, 2017 2:13 pm
Location: Lille

Wich version for FEM shell development?

Postby Groguigui » Fri Mar 10, 2017 3:47 pm

Hello everybody!

I am new FreeCAD user, and maybe a futur developper because my lab would like to perform our work with this soft.
Actually, I try this version :

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.6706 (Git)
Build type: Release
Branch: releases/FreeCAD-0-16
Hash: f86a4e411ff7848dea98d7242f43b7774bee8fa0
Python version: 2.7.8
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

But it is not possible to mesh a shell, and I would like to install the development version, so I have some questions :
1) Is there a branch to privilege when acquiring the version 0.17 that we will compile on Linux?
2) Is there, for example, a branch specific to the development of the FEM?
3) Do you have some advices to take a good version to work on surface mesh?
4) Do you know if FreeCAD can handle the mixture of shell elements and volumic elements? The contacts between both?

Thanks :)
User avatar
Kunda1
Posts: 612
Joined: Thu Jan 05, 2017 9:03 pm

Re: Wich version for FEM shell development?

Postby Kunda1 » Fri Mar 10, 2017 4:39 pm

Groguigui wrote:Hello everybody!

I am new FreeCAD user, and maybe a futur developper because my lab would like to perform our work with this soft.
Actually, I try this version :

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.6706 (Git)
Build type: Release
Branch: releases/FreeCAD-0-16
Hash: f86a4e411ff7848dea98d7242f43b7774bee8fa0
Python version: 2.7.8
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

But it is not possible to mesh a shell, and I would like to install the development version, so I have some questions :
1) Is there a branch to privilege when acquiring the version 0.17 that we will compile on Linux?
2) Is there, for example, a branch specific to the development of the FEM?
3) Do you have some advices to take a good version to work on surface mesh?
4) Do you know if FreeCAD can handle the mixture of shell elements and volumic elements? The contacts between both?

Thanks :)

FYI, all the cool FEM stuff is in the experimental 0.17 dev version.
Edit:
Bernd's repo is where a lot of the pre-merging in to master is happening. But merges are happening very rapidly to master because FEM has seen a lot of development recently, so most likely if you stay current with 0.17 HEAD you'd get to play with the latest FEM stuff.
User avatar
NormandC
Posts: 12031
Joined: Sat Feb 06, 2010 9:52 pm
Location: Québec, Canada

Re: Wich version for FEM shell development?

Postby NormandC » Sat Mar 11, 2017 6:38 am

Hello Groguigui,

(To others, for reference there's also a discussion over the French forum: https://forum.freecadweb.org/viewtopic.php?f=12&t=21197)

bernd wrote a script to automate compilation of the latest libraries required for FEM (OCC, netgen, vtk, MED-file) along with FreeCAD for Debian Jessie or Ubuntu 16.04 LTS (Xenial). At the moment, that's your best bet. https://forum.freecadweb.org/viewtopic.php?f=4&t=18967

I'm not sure it's currently possible to get the same result by compiling on Windows.

On Ubuntu, we provide a Daily Builds PPA repository with a version of FreeCAD built daily from the FreeCAD source code. Updates are pushed through the Ubuntu Update Manager. It's the easiest way on any operating system to get the latest FreeCAD, basically without lifting a finger. The problem is that the FEM guys' work depends on versions of libraries that are not available in the Debian/Ubuntu official software repositories, and the older libraries they hold have various conflicts.

I am working on solving this issue by packaging the requisite libraries in the FreeCAD Daily Builds PPA. I already migrated the PPA to OCCT 7.1.0 this week. But due to that change, I had to disable netgen (one of two tetrahedral mesh generators available in FreeCAD). Next is to migrate netgen to v5.3.1 and re-enable it, after that it will be MED-file and VTK 7. I am not an expert packager but I'm getting great help from a few members of the FreeCAD community so I am moderately optimistic.

My recommendation is to set up a Linux box (or a dual boot) with Ubuntu 16.04 LTS then get started with bernd's script. Hopefully, we'll get the PPA up-to-date at some point and then you'll be able to switch to it. Of course, if you plan to do development then compiling will be necessary, but you'd be able to use the packaged occt, netgen etc. libraries instead of having to compile them first.
User avatar
bernd
Posts: 3860
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: Wich version for FEM shell development?

Postby bernd » Sun Mar 12, 2017 8:45 am

it seam most of your questions has been answered so far ...
Groguigui wrote:4) Do you know if FreeCAD can handle the mixture of shell elements and volumic elements? The contacts between both?
https://forum.freecadweb.org/viewtopic. ... 84#p162984
User avatar
Groguigui
Posts: 8
Joined: Thu Mar 09, 2017 2:13 pm
Location: Lille

Re: Wich version for FEM shell development?

Postby Groguigui » Mon Mar 13, 2017 4:03 pm

Thanks,

Bernd, your link was interesting but it doesn't answer about my question 4). May be I'm blind (or not enough good in english :lol: )!

Now, if to mesh a simple surface 2D with draft in FreeCAD is impossible in 0.16 Version, I'm doing a mesh a imported complex surface without problem in a same version! :shock:
For freeCAD, imported surface or drawed surface is different? In INP file it is the same.

I go back to work, I have a lot of thing to test. ;)
User avatar
bernd
Posts: 3860
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: Wich version for FEM shell development?

Postby bernd » Mon Mar 13, 2017 6:50 pm

Groguigui wrote:Bernd, your link was interesting but it doesn't answer about my question 4). May be I'm blind (or not enough good in english :lol: )!
Ahh we may missunderstood. I thought you would like to analyze a mixture of shell and volume elements by FreeCAD FEM. For the analysis with FreeCAD FEM we gone use CalculiX and CalculiX uses abacus file format inp. Thus to analyze volume and shell elements in one analysis we need a inp file exporter which exports shell and volume elements and the appropriate sets to inp. This is what the link was about, to extend the inp file exporter which is developed in writeAbaqus.

Back to your question ... Means you are interested in the FEM mesh only. Just to understand what you are looking for see attached screen ... Is it what you are looking for?

screen.jpg
screen.jpg (980.6 KiB) Viewed 122 times
User avatar
bernd
Posts: 3860
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: Wich version for FEM shell development?

Postby bernd » Mon Mar 13, 2017 7:07 pm

Attached the FreeCAD file. The problem seams the view provider ... The faces between the cubes are meshed and the data is stored in the FEM mesh object, but the viewprovieder does not show the mesh faces because there are volumes and thus only the faces of the volumes are displayed. We need to have a look at this one. This is for sure a most wanted feature ...

vol-shell-mesh.fcstd
(179.12 KiB) Downloaded 2 times

screen.jpg
screen.jpg (311.96 KiB) Viewed 115 times



EDIT:
Best way to really proof FreeCAD FEM mesh data structure and Mesh objects are able to handle mixed meshes is to load the example provided in this post, save the FEM mesh to unv and open in GMSH. It will show the faces between the cubes are meshed :D
Last edited by bernd on Tue Mar 14, 2017 4:08 pm, edited 2 times in total.
User avatar
Groguigui
Posts: 8
Joined: Thu Mar 09, 2017 2:13 pm
Location: Lille

Re: Wich version for FEM shell development?

Postby Groguigui » Tue Mar 14, 2017 2:25 pm

Thank you Bernd! :P

For example, if I mesh Shape, Shape001 and Face001 with your file, and after that I apply some boundaries conditions (like FemConstraintFixe and FemConstraintForce) when I write inp.file in mechanical analysis, nothing happen. Only : check dependencies.

You too? Is it possible to write inp.file and calculate with shell and volumic elements?
User avatar
bernd
Posts: 3860
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: Wich version for FEM shell development?

Postby bernd » Tue Mar 14, 2017 3:15 pm

Groguigui wrote:Is it possible to write inp.file and calculate with shell and volumic elements?
No, not at the moment! I have posted the link before. There is a discussion about extending the inp file writer to write shell and volume element in one analysis.

The FEM mesh data structure supports mixed vol and shell meshes but the FreeCAD calculix analysis does not at the moment. But some guys really would like to see this feature, thus there is some development going on. Again, see https://forum.freecadweb.org/viewtopic. ... 84#p162984
User avatar
Groguigui
Posts: 8
Joined: Thu Mar 09, 2017 2:13 pm
Location: Lille

Re: Wich version for FEM shell development?

Postby Groguigui » Tue Mar 14, 2017 3:56 pm

Ok, thank you very much.

I hadn't understood!