Fem constraint contact

About the development of the FEM module/workbench.

Moderator: bernd

JV_3D
Posts: 41
Joined: Fri Dec 23, 2016 4:45 am

Re: Fem constraint contact

Postby JV_3D » Fri May 05, 2017 12:11 am

Thanks for the clarification, I think I will install the 0.17 beta version for the test with FEM analysis
User avatar
bernd
Posts: 8217
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: Fem constraint contact

Postby bernd » Fri May 05, 2017 5:50 pm

JV_3D wrote:Thanks for the clarification, I think I will install the 0.17 beta version for the test with FEM analysis
Since you are on Windows, no installation is needed, just unpack the downloaded file and run the FreeCAD.exe.
adrianer
Posts: 1
Joined: Thu Aug 03, 2017 2:03 am

Re: Fem constraint contact

Postby adrianer » Thu Aug 03, 2017 1:18 pm

makkemal wrote:
Thu May 12, 2016 4:10 pm
@vejmarie
compile this tree
https://github.com/makkemal/FreeCAD/tree/rtd_hindlemp
example attached

@bernd don't look at the code or how the commits are staged :twisted:

Contact.PNG
Hi everyone. I tried to run that example but i've a error message. someone know what happend?. I have FreeCAD 0.17 Rev 11714 (Git) - Ubuntu 16.04. I can run others fems methods Ok, but I can not make it work with Contact method. Regards.

Image
User avatar
bernd
Posts: 8217
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: Fem constraint contact

Postby bernd » Thu Aug 03, 2017 2:34 pm

In this topic are some newer examples ... https://forum.freecadweb.org/viewtopic.php?f=18&t=20276
User avatar
bernd
Posts: 8217
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: Fem constraint contact

Postby bernd » Thu Aug 03, 2017 4:14 pm

try this ...

contact-example-udated2.fcstd
(558.07 KiB) Downloaded 51 times


screen.jpg
screen.jpg (282.91 KiB) Viewed 964 times


OS: Debian GNU/Linux 8.9 (jessie)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.11733 (Git)
Build type: Debug
Branch: master
Hash: b7110d0dfe8941d6b316f4111d3559e0b969fe5e
Python version: 2.7.9
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 7.0.0
Locale: German/Switzerland (de_CH)
UR_
Posts: 935
Joined: Tue Jan 03, 2017 8:42 pm

Re: Fem constraint contact

Postby UR_ » Thu Aug 03, 2017 6:05 pm

adrianer wrote:
Thu Aug 03, 2017 1:18 pm
but I can not make it work with Contact method
reworked example
PointofContact.png
PointofContact.png (232.49 KiB) Viewed 948 times

Changes:
  • pressure wasn't able to deflect as much as needed to contact sphere
  • added some mesh refinements at contact area
  • restrict contact area
  • increased contact stiffness to see any stress
  • added some friction (ccx loves friction)
  • reworked model (boolean fragments and compound filter)
  • reworked sphere's fix (was a little bit weird)

File (fem results stripped because of file size):
BeamBallContact.stripped.FCStd
(408.82 KiB) Downloaded 48 times

Done with:
OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.11731 (Git)
Build type: Release
Branch: master
Hash: 46aab48e6ae2855faee77cb925b498bf4dd738e5
Python version: 2.7.8
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.1.0
Locale: German/Germany (de_DE)
gmesh_3.0.4
ccx_2.12_MTNO
User avatar
bernd
Posts: 8217
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: Fem constraint contact

Postby bernd » Thu Aug 03, 2017 6:43 pm

wow cool ...

in the regard of pressure and sphere fix, the idea was as follows (AFAIR), the sphere moves up and the pressure acted like a stiffness for the cantilever

but it does not matter eventually ...

bernd
UR_
Posts: 935
Joined: Tue Jan 03, 2017 8:42 pm

Re: Fem constraint contact

Postby UR_ » Thu Aug 03, 2017 6:58 pm

Sorry,
should next better read WHOLE thread. :oops:
JV_3D
Posts: 41
Joined: Fri Dec 23, 2016 4:45 am

Re: Fem constraint contact

Postby JV_3D » Tue Aug 29, 2017 2:49 am

Hello everyone I am presenting some issues with the contact constrain

1) I downloaded one of last the example in this thread 'contact-example-udated2.fcstd' posted by user bernd, but I am finding some issues when recreating the example (starting new Analysis with same solid/parameters). After simulating I got different results (9 different)
Capture-fem1.JPG
Capture-fem1.JPG (76.24 KiB) Viewed 871 times
Why is this different results means? I suppose the last one is the definitive, so I should omit the other ones??

2) I am using other example but it does not generate any results, CalculiX show the following error, I reduce the contact stiffness but nothing seem to happen, I also try with 0.1 for friction factor instead of 0 as UR_ suggested, but nothing
how should I continue? Both materials are steel.

divergence allowed: residual force too large
divergence; the increment size is decreased to 9.765625e-04
the increment is reattempted
reducing the constant stiffnesses by a factor of 100
*ERROR: too many cutbacks
best solution and residuals are in the frd file

I am attaching the file if someone as any time to check it. The version I am using is the lastest available for Windows:
OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.11935 (Git)
Build type: Release
Branch: master
Hash: a5bc70cca0d2eaa56709603521650ccb3d8d926c
Python version: 2.7.8
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.1.0
Locale: English/UnitedStates (en_US)
Attachments
connector_edit_2.FCStd
(60.12 KiB) Downloaded 33 times
User avatar
bernd
Posts: 8217
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: Fem constraint contact

Postby bernd » Tue Aug 29, 2017 5:01 am

what ccx version do you use?