Fem constraint contact

About the development of the FEM module/workbench.

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JV_3D
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Re: Fem constraint contact

Post by JV_3D »

Thanks for the clarification, I think I will install the 0.17 beta version for the test with FEM analysis
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bernd
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Re: Fem constraint contact

Post by bernd »

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
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Re: Fem constraint contact

Post by adrianer »

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.

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bernd
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Re: Fem constraint contact

Post by bernd »

In this topic are some newer examples ... https://forum.freecadweb.org/viewtopic.php?f=18&t=20276
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bernd
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Re: Fem constraint contact

Post by bernd »

try this ...

contact-example-udated2.fcstd
(558.07 KiB) Downloaded 116 times


screen.jpg
screen.jpg (282.91 KiB) Viewed 2813 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_
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Re: Fem constraint contact

Post by UR_ »

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 2797 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 108 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
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bernd
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Re: Fem constraint contact

Post by bernd »

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 ...

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UR_
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Re: Fem constraint contact

Post by UR_ »

Sorry,
should next better read WHOLE thread. :oops:
JV_3D
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Re: Fem constraint contact

Post by JV_3D »

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 2720 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 81 times
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bernd
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Re: Fem constraint contact

Post by bernd »

what ccx version do you use?
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