Is FEM Running?

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PrzemoF
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Re: Is FEM Running?

Postby PrzemoF » Tue Aug 23, 2016 5:41 pm

@easyw-fc: OK, we need to learn to walk first. Can you make a simple cube, fix it on one side, add pressure or another and run calculations?

P.S. Ubuntu or fedora is the way to go :D
pbhuter
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Re: Is FEM Running?

Postby pbhuter » Tue Aug 23, 2016 8:29 pm

My FEM file is ~37MB, so I guess that is too big to upload to the forum.

I have tried this on Ubuntu 16.04 and Windows 7, both 64-bit with FreeCAD 0.16.

It worked fine when I just followed the example problem (posted as a link in original post), but my geometry does not work. I tried just doing the base octagon, but that had the same issue. I did discover that my mirror included the base octagon, so I pulled out the original octagon and just had the two parts that I uploaded earlier today.

I really do appreciate all that everyone is doing to try and help me with this. I have kind of taken a day off from CAD/FEM, but I will continue to post anything that I try and any results that I come up with.
Korslight
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Re: Is FEM Running?

Postby Korslight » Thu Aug 25, 2016 3:03 am

pbhunter,

So I ran your simulation, and it pretty much exploded, but I am unsure if I applied how you wanted me to. I applied a fixed constraint to the bottom face of the bottom and a force constraint of the top face of the top (pointing up). [i.e. a uniaxial force]

Weirdly I was unable to get the constraints to show up in the GUI window which I have not experienced before. To run the simulation I had to go into the part workbench and boolean union the parts together. I also noticed on the sketch is was under-constrained in Pad002 which can cause issues, but I did not bother constraining the sketch. Attached below are the results.

Please let me know your thoughts and if I performed the simulation constraints correctly. I think your force is a little excessive at 3.625 MN

Cheers,
Korslight
Attachments
5 Mesh.JPG
5 Mesh.JPG (25 KiB) Viewed 2191 times
4 Force.JPG
4 Force.JPG (33.87 KiB) Viewed 2192 times
3 displacement.JPG
3 displacement.JPG (79.88 KiB) Viewed 2192 times
2 Slider(factor of 1).JPG
2 Slider(factor of 1).JPG (50.11 KiB) Viewed 2192 times
1 Von mises stress.JPG
1 Von mises stress.JPG (80.08 KiB) Viewed 2192 times
Korslight
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Re: Is FEM Running?

Postby Korslight » Thu Aug 25, 2016 3:13 am

Forgot to add the material screenshot...

For some reason it would not let me add it to the last comment (but the size of all the pictures were pretty small)
Attachments
0 Material.JPG
0 Material.JPG (24.96 KiB) Viewed 2190 times
Korslight
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Re: Is FEM Running?

Postby Korslight » Thu Aug 25, 2016 3:53 am

Hmm I am not sure though. Maybe I did something wrong or the software is not performing correctly.

When I found the area of the top face using Mario52's FCInfo Macro http://www.freecadweb.org/wiki/index.ph ... nfo#Script I found the cross sectional area of the long beams to be 0.00099528932188 m².

So the corresponding axial stress would be (3625000 N/0.000995289321881m²) = 3.64 GPa as sigma=F/A

Sigma = E*Epsilon

3.64 GPa = (68.9 GPa)*Epsilon

Epsilon = 0.05286 m/m

It has been awhile since I have been in school so please forgive if I had calculated anything incorrectly. This isn't an absurd amount of strain and I am unsure why it caused the explosion in this simulation as the stress should theoretically be well bellow the yield stress.

Anyone have any idea.
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easyw-fc
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Re: Is FEM Running?

Postby easyw-fc » Fri Aug 26, 2016 9:34 pm

Hi to all and sorry for delay in my reply...
I spent some time in testing the best solution for me to have access to thermo-mechanical simulation...
makkemal wrote:@Maurice
A windows version of 0.16 with thermo-mechanical included can be found here
http://opensim.co.za/index.php?option=c ... Itemid=618
To simplify chip analysis need a few improvements on multi-body meshing
viewtopic.php?f=18&t=16750
One of my guys is working on including radiation heat transfer

Get a unbuntu machine :D
PrzemoF wrote:@easyw-fc: OK, we need to learn to walk first. Can you make a simple cube, fix it on one side, add pressure or another and run calculations?

P.S. Ubuntu or fedora is the way to go :D
Hi @makkemal @ PrzemoF
I manage to run FEM on windows 10 64b following @bernd suggestion
I use FC 017 7745 for mesh generation of my parts
then I copy part and mesh generated to FC 017 8293
In FC 017 8293 I make my FEM analysis
that is a bit messy but is working fine for mechanical analysis
fem-mechanical-ok.png
fem-mechanical-ok.png (192.15 KiB) Viewed 2168 times
I followed this tutorial
viewtopic.php?f=18&t=17066
(https://www.youtube.com/watch?v=wAJe1R5NDGw)

for thermo mechanical analysis I tried this tutorial and it seems to work too
https://youtu.be/Fy9VZuLm9FI
HSig wrote:
easyw-fc wrote:Is there a mini video tutorial to learn the FreeCAD FEM thermo analysis?
Just a basic one would be great!
I googled but there are only quite old video ...
thanks a lot for your effort and support!
Maurice
Hi Maurice, just made a simple screencast-tutorial, thermal deflection of a L-beam.

You find it here: https://youtu.be/Fy9VZuLm9FI
fem-thermo-mechanical.png
fem-thermo-mechanical.png (177.87 KiB) Viewed 2168 times
what I'm still not able to reproduce are the two thermo mechanical simulation as on i.e. these files
simplechip_05_multiple_mat.fcstd
from
viewtopic.php?f=18&t=16749&start=40#p133612
or
simple_chip.fcstd
from
viewtopic.php?f=18&t=16749&start=40#p133620

a very mini video tutorial of i.e. simple_chip.fcstd would be super useful :D
thank you again in advance for any advice
Maurice
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makkemal
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Re: Is FEM Running?

Postby makkemal » Sun Aug 28, 2016 1:03 pm

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easyw-fc
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Re: Is FEM Running?

Postby easyw-fc » Mon Aug 29, 2016 9:18 am

thanks so much!
here is a simulation I did on a medium complex board with bounding boxes and thermo analysis that I did in windows 10 64b :D
fem-thermo-pcb-ok.png
fem-thermo-pcb-ok.png (592.87 KiB) Viewed 2117 times
That is a board developed in KiCad and exported to MCAD with kicad StepUp FreeCAD macro using bounding boxes export option
please keep me updated on FEM evolution ;)
Maurice
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cnirbhay
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Re: Is FEM Running?

Postby cnirbhay » Tue Aug 30, 2016 12:57 pm

easyw-fc wrote:Hi to all and sorry for delay in my reply...
I spent some time in testing the best solution for me to have access to thermo-mechanical simulation...
makkemal wrote:@Maurice
A windows version of 0.16 with thermo-mechanical included can be found here
http://opensim.co.za/index.php?option=c ... Itemid=618
To simplify chip analysis need a few improvements on multi-body meshing
viewtopic.php?f=18&t=16750
One of my guys is working on including radiation heat transfer
This thermo-mechanical version is having some problem, I guess. CCX input file writer gets stuck at 50%.
Any solutions?
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makkemal
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Re: Is FEM Running?

Postby makkemal » Tue Aug 30, 2016 2:41 pm

@cnirbhay CCX input file writer gets stuck at 50%
Check that your calculix preferences points to the correct ccx.exe
Make sure the path to the ccx.exe file does not contain any spaces or special characters