Pressure constraint on a shell

[fjshenriques]

Hello everyone. I am new at FreeCAD forum and I need a help ( I am a beginer using FEA in FreeCAD).

I am having problem in order to proceed presure shell analisys with FreeCAD 0.19. I have found this post from 2020 with similar problem and used the model available in it for a membrane in order to evaluate and test. But the erros are the same for a model I am tring to do. The firt erro was regarding to Meshgoup. (Pressure on shell mesh at the moment only supported for meshes with appropriated group data)

After I have added the group, I had run again but the software returned another error: (Error: Something went wrong in getting the group element faces)
Attached the files that i worked over.

Could any one help in ths subeject? I believe if I can run this simple model I would be have good chances to run my models.

[NewJoker]

@fjshenriques When I opened your file and submitted the analysis, I got empty results. Then I regenerated the mesh without changing any settings, like thschrader did. Then it worked and I got the results.

Which version of FreeCAD are you using ? Paste your About FreeCAD info here, according to the red banner. For the FEM workbench it's best to use the newest possible version since there are tons of fixes. I used 0.20 but 0.21 dev would be even better.

Code: Select all

OS: Windows 10 Version 2009
Word size of FreeCAD: 64-bit
Version: 0.20.29177 (Git)
Build type: Release
Branch: releases/FreeCAD-0-20
Hash: 68e337670e227889217652ddac593c93b5e8dc94
Python 3.8.10, Qt 5.15.2, Coin 4.0.1, Vtk 8.2.0, OCC 7.6.2
Locale: Polish/Poland (pl_PL)

[fjshenriques]

Hi NewJoker

I run again but when I start "Write .inp file" still return the same error.

Below the version I am using.

OS: Windows 10 Version 2009
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24267 +148 (Git)
Build type: Release
Branch: Branch_0.19.4
Hash: 476ecf091941bead59b14e44afa6064d5a66afa3
Python version: 3.8.6+, Qt version: 5.15.2, Coin version: 4.0.1, OCC version: 7.5.3
Locale: Portuguese/Brazil (pt_BR)

I will try download a new version but I am only see 0.20. The 0.21 is not available for me...
If you have another idea I appreciate.

Regards

[NewJoker]

I run again but when I start "Write .inp file" still return the same error.

I tried in the newest build of 0.21 (details below) and the same behavior as in 0.20 can be observed.

Code: Select all

OS: Windows 10 Version 2009
Word size of FreeCAD: 64-bit
Version: 0.21.30143 (Git)
Build type: Release
Branch: master
Hash: a72bf218f9917df37e811d7e73a36333282028f5
Python 3.10.5, Qt 5.15.4, Coin 4.0.0, Vtk 9.1.0, OCC 7.6.2
Locale: Polish/Poland (pl_PL)

I will try download a new version but I am only see 0.20. The 0.21 is not available for me...

You can find 0.21 dev version builds here: https://github.com/FreeCAD/FreeCAD-Bund ... kly-builds

They don't require installation, just download, unzip and use.

[thschrader]

I run again but when I start "Write .inp file" still return the same error.

Here your file runs without error.
My system:

Code: Select all

OS: Windows 10 Version 2009
Word size of FreeCAD: 64-bit
Version: 0.20.1.29410 (Git)
Build type: Release
Branch: releases/FreeCAD-0-20
Hash: f5d13554ecc7a456fb6e970568ae5c74ba727563
Python 3.8.10, Qt 5.15.2, Coin 4.0.1, Vtk 8.2.0, OCC 7.6.3
Locale: German/Germany (de_DE)
Installed mods: 
  * BIM
  * CfdOF 1.17.6
  * Curves 0.3.0
  * Defeaturing_WB
  * dodo
  * Fasteners
  * FEM_FrontISTR 0.1.0
  * Manipulator 1.4.3
  * Plot
  * Reinforcement
  * WorkFeature

[fjshenriques]

thschrader and NewJoker

Thank you guys for the support. I did not have time to download the version 0.21. But I already have the version 0.20 in another PC and testing with other application combining shell and pressure the erros are the same as showed for this simples example.
One doubt came to my mind. Is it possible I need a module or activate some specific preference?
I say this once I have noted in the thschrader's mods installed one that could be for FEM analysis (FEM_FrontISTR 0.1.0).
Sorry if I ask basic question but I am a beginner with FreeCAD FEM.

[NewJoker]

One doubt came to my mind. Is it possible I need a module or activate some specific preference?
I say this once I have noted in the thschrader's mods installed one that could be for FEM analysis (FEM_FrontISTR 0.1.0).

You don't need any additional modules. FEM_FrontISTR is a separate module for analyses with a different solver.

[fjshenriques]

Hello Again,

You will not believe. I changed the language from Portugues to English into edit>preferences menu and have run again. And it worked! I will do some more tests.
Could it be a bug?

[Danial Iskhakov]

It's a bug but looks like not concern interface localization. I've ukrainian interface in Windows and english one in FreeCAD. But issue Pressure constraint on a shell also appears quite often. Some times it's heal by changing mesh density. But when try combine pressure with force and self weight, pressure don't take in account at all.