FEM analysis issue

About the development of the FEM module/workbench.

Moderator: bernd

XtyM
Posts: 7
Joined: Fri Oct 11, 2019 1:18 pm

FEM analysis issue

Postby XtyM » Fri Oct 11, 2019 1:44 pm

Hi;

I am trying replicate this model from youtube https://www.youtube.com/watch?v=Y9l1zYnMj4g

I did the model, (it is attached). During the mesh generation I received the error that I have previously read in this forum about (gmsh 4.X) Gmsh error: Unknown element type for UNV export (MSH type 15)
https://forum.freecadweb.org/viewtopic.php?t=33946

The mesh is generated with this warning, (if I reduce the resolution of the mesh, this warning disappears and a new one appears indicating the distortion of the average values in the avg mesh) in any case I have said situations I have been able to start the calculation with other models And has worked.

The problem arises when I start the calculation with calculix which never ends up entering in exorbitant times for what this is (unless there is an error that does not find a solution during the iterations .... I do not think this is the case because the model is identical to the one made in the video whose link I have attached).


OS: "Fedora release 30 (Thirty)"
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.Unknown
Build type: Unknown
Python version: 3.7.3
Qt version: 4.8.7
Coin version: 3.1.3
OCC version: 6.9.1.oce-0.18
Locale: Swedish/Sweden (sv_SE)


Om Calculix i did compile binary accord this post https://forum.freecadweb.org/viewtopic.php?f=18&t=34024, I did check it with another model and this did work.

Regards.
Attachments
Skärmbild från 2019-10-11 15-19-26.png
Running Calculix 2.15
Skärmbild från 2019-10-11 15-19-26.png (181.25 KiB) Viewed 424 times
Contacto.FCStd
Model
(732.79 KiB) Downloaded 8 times
Last edited by Kunda1 on Sat Oct 12, 2019 3:09 pm, edited 5 times in total.
Reason: fixed typo in thread title
XtyM
Posts: 7
Joined: Fri Oct 11, 2019 1:18 pm

Re: FEM analys issue

Postby XtyM » Fri Oct 11, 2019 6:11 pm

Can someone load the file and execute an analysis with FEM calculix to check if it is a issue only with my freecad?? In my pc calculix is running but never stop. the model was created like in the video attached, the "solver" should take less than 1 min to this model. Is there something what i am missing up? or it is just a fail into the gmsh mesh and calculix solver?.

btw my gmsh version is 4.1.5

Thanks in advice.
UR_
Posts: 991
Joined: Tue Jan 03, 2017 8:42 pm

Re: FEM analys issue

Postby UR_ » Sat Oct 12, 2019 1:48 pm

Some remarks regarding contact analyses:


- Better use linear elements otherwise calculations are very time consuming

Screenshot 005.png
Screenshot 005.png (15.06 KiB) Viewed 369 times

Please obey rules regarding how to assign master an slave faces


- master/slave assignment:
The larger of the two surfaces should act as the master surface.
If the surfaces are of comparable size, the surface on the stiffer body should act as the master surface.
If the surfaces are of comparable size and stiffness, the surface with the coarser mesh should act as the master surface.



Now ccx_2.15_pardiso needs 4 sec to solve ;)
User avatar
Kunda1
Posts: 5781
Joined: Thu Jan 05, 2017 9:03 pm

Re: FEM analysis issue

Postby Kunda1 » Sat Oct 12, 2019 3:09 pm

Moved to FEM subforum
Want to contribute back to FC? Checkout:
#lowhangingfruit | Use the Source, Luke. | How to Help FreeCAD | How to report FC bugs and features
XtyM
Posts: 7
Joined: Fri Oct 11, 2019 1:18 pm

Re: FEM analys issue

Postby XtyM » Mon Oct 14, 2019 2:53 am

Hi thank you. I changed the value of element order to 1 like you did indicate, but calculix stay running and i need close the process via terminal. I dont know what is going wrong.

After i did complie calculix i checked libraries and it was result

[jorge@fedora31 Calculix_2.15]$ ldd ./ccx_2.15
linux-vdso.so.1 (0x00007ffeeb3cb000)
libarpack.so.2 => /lib64/libarpack.so.2 (0x00007f258f8b8000)
liblapack.so.3 => /lib64/liblapack.so.3 (0x00007f258f228000)
libblas.so.3 => /lib64/libblas.so.3 (0x00007f258f1d0000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f258f1a8000)
libgfortran.so.5 => /lib64/libgfortran.so.5 (0x00007f258ef00000)
libm.so.6 => /lib64/libm.so.6 (0x00007f258edb8000)
libmvec.so.1 => /lib64/libmvec.so.1 (0x00007f258ed88000)
libc.so.6 => /lib64/libc.so.6 (0x00007f258ebb8000)
libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f258eb98000)
libquadmath.so.0 => /lib64/libquadmath.so.0 (0x00007f258eb48000)
libopenblasp.so.0 => /lib64/libopenblasp.so.0 (0x00007f258c6c8000)
/lib64/ld-linux-x86-64.so.2 (0x00007f258fb30000)
Attachments
Skärmbild från 2019-10-14 04-51-35.png
Skärmbild från 2019-10-14 04-51-35.png (210.24 KiB) Viewed 319 times
Skärmbild från 2019-10-14 04-47-46.png
Skärmbild från 2019-10-14 04-47-46.png (260.76 KiB) Viewed 319 times
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bernd
Posts: 8440
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: FEM analys issue

Postby bernd » Mon Oct 14, 2019 8:11 am

UR_ wrote:
Sat Oct 12, 2019 1:48 pm
- Better use linear elements otherwise calculations are very time consuming

- master/slave assignment:
The larger of the two surfaces should act as the master surface.
If the surfaces are of comparable size, the surface on the stiffer body should act as the master surface.
If the surfaces are of comparable size and stiffness, the surface with the coarser mesh should act as the master surface.
addend here: FEM_ConstraintContact
UR_
Posts: 991
Joined: Tue Jan 03, 2017 8:42 pm

Re: FEM analysis issue

Postby UR_ » Mon Oct 14, 2019 10:01 am

XtyM wrote:
Mon Oct 14, 2019 2:53 am
After i did complie calculix i checked libraries ...

Perhaps you should solve some reference inp files before to ensure it's a proper build.


Please run from shell (without using FreeCAD)

Official example inp file from test suite and result file for reference:

From ccx Test Suite.7z
(1.32 KiB) Downloaded 7 times

BTW, for using FEM WB it's recommend to use latest FreeCAD build, ATM version 0.19
XtyM
Posts: 7
Joined: Fri Oct 11, 2019 1:18 pm

Re: FEM analysis issue

Postby XtyM » Mon Oct 14, 2019 10:40 am

I did run the text with the file you did posted, It was ok except for what is taking only 1 CPU.

I have load the output from terminal and the check file what coincide exact with the file downloaded.

About FEM_ConstraintContact i think i have tested all combinations possibles.

Thank you for your support.

Regards.!
Attachments
Verification-Calculix output.7z
Files (checking calculix)
(2.76 KiB) Downloaded 7 times
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bernd
Posts: 8440
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: FEM analysis issue

Postby bernd » Mon Oct 14, 2019 12:11 pm

UR_ wrote:
Mon Oct 14, 2019 10:01 am
Official example inp file from test suite and result file for reference:
From ccx Test Suite.7z
just as a hint for others the ccx test suite is meant not FreeCADs one.
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bernd
Posts: 8440
Joined: Sun Sep 08, 2013 8:07 pm
Location: Zürich, Switzerland

Re: FEM analysis issue

Postby bernd » Mon Oct 14, 2019 12:13 pm

UR_ wrote:
Mon Oct 14, 2019 10:01 am
Official example inp file from test suite and result file for reference:
From ccx Test Suite.7z
if you make a FreeCAD file (or even better immediately code it in python) for it I will add it to the FreeCAD FEM examples. https://github.com/FreeCAD/FreeCAD/tree ... emexamples