Enforced pressure-constraint in static analysis

About the development of the FEM module/workbench.

Moderator: bernd

nicoguaro
Posts: 15
Joined: Wed Sep 16, 2015 11:37 pm

Enforced pressure-constraint in static analysis

Postby nicoguaro » Thu Mar 23, 2017 9:25 pm

Hello,

I am trying to run a simulation where I impose a displacement in a cantilever beam. In this case, there is no imposition of tractions. There will be stresses as reactions to the imposed displacement, but FreeCAD is not allowing this case.

This is the error that I get
screenshot.png
screenshot.png (6.75 KiB) Viewed 894 times

OS: Windows 8.1
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
fandaL
Posts: 333
Joined: Thu Jul 24, 2014 8:29 am

Re: Enforced pressure-constraint in static analysis

Postby fandaL » Thu Mar 23, 2017 10:41 pm

For using FEM module download 0.17 dev version, e.g.

Code: Select all

 FreeCAD_0.17.10634_x64_dev_win.7z
from https://github.com/FreeCAD/FreeCAD/releases
Prerequisities are fixed there and you will find a lot of new features.
nicoguaro
Posts: 15
Joined: Wed Sep 16, 2015 11:37 pm

Re: Enforced pressure-constraint in static analysis

Postby nicoguaro » Fri Mar 24, 2017 5:40 pm

It works, as you mentioned. Thanks.

The post-processing is not clear though.
UR_
Posts: 866
Joined: Tue Jan 03, 2017 8:42 pm

Re: Enforced pressure-constraint in static analysis

Postby UR_ » Fri Mar 24, 2017 6:25 pm

Attached you can find a small example.
Left face is fixed, right face gets a displacement of 10 mm.
Ringauge.png
Ringauge.png (209.12 KiB) Viewed 832 times
Ringauge.FCStd
(22.34 KiB) Downloaded 16 times
if you are interested in reaction forces caused by this deflection, you have to edit ccx-input-file (here Fillet_mesh.inp)
before ccx's execution
Please insert reddish output request by hand
***********************************************************
** Outputs --> frd file
** written by write_outputs_types function
*NODE FILE
U
*EL FILE
S, E
** outputs --> dat file
*NODE PRINT , NSET=Nall
U
*NODE PRINT , NSET=FemConstraintFixed, TOTALS=ONLY
RF

*EL PRINT , ELSET=Eall
S

***********************************************************
In ccx-output-file (Fillet_mesh.dat) you can find that 42000 N needs to be loaded
total force (fx,fy,fz) for set FEMCONSTRAINTFIXED and time 0.1000000E+01

-4.230049E+04 2.246115E-07 5.220707E-08
Fillet_Mesh_INP_DAT files.zip
(139.91 KiB) Downloaded 18 times
Let us know if you are looking for something else :roll:
User avatar
bernd
Posts: 8046
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: Enforced pressure-constraint in static analysis

Postby bernd » Thu Jun 06, 2019 8:16 am

issue #2934

updated file to 0.19 ...

Ringauge-2.FCStd
(278.63 KiB) Downloaded 6 times
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bernd
Posts: 8046
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: Enforced pressure-constraint in static analysis

Postby bernd » Thu Jun 06, 2019 8:18 am

an file updated be the original author can be found here: https://forum.freecadweb.org/viewtopic. ... 49#p312618