Enforced pressure-constraint in static analysis

About the development of the FEM module/workbench.

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nicoguaro
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Enforced pressure-constraint in static analysis

Post by nicoguaro »

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 2394 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: 440
Joined: Thu Jul 24, 2014 8:29 am

Re: Enforced pressure-constraint in static analysis

Post by fandaL »

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
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Re: Enforced pressure-constraint in static analysis

Post by nicoguaro »

It works, as you mentioned. Thanks.

The post-processing is not clear though.
UR_
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Re: Enforced pressure-constraint in static analysis

Post by UR_ »

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 2332 times
Ringauge.FCStd
(22.34 KiB) Downloaded 61 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 63 times
Let us know if you are looking for something else :roll:
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bernd
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Re: Enforced pressure-constraint in static analysis

Post by bernd »

issue #2934

updated file to 0.19 ...

Ringauge-2.FCStd
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bernd
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Re: Enforced pressure-constraint in static analysis

Post by bernd »

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