Is FEM Running?

[PrzemoF]

@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

[pbhuter]

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]

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

[Korslight]

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)

[Korslight]

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.

[easyw-fc]

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...

@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

@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

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 (192.15 KiB) Viewed 2209 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

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 (177.87 KiB) Viewed 2209 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
thank you again in advance for any advice
Maurice

[makkemal]

see
viewtopic.php?f=18&t=17066&p=135608#p135608 for demo

https://youtu.be/CGSrqvAZ97M

[easyw-fc]

see
viewtopic.php?f=18&t=17066&p=135608#p135608 for demo

https://youtu.be/CGSrqvAZ97M

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

fem-thermo-pcb-ok.png (592.87 KiB) Viewed 2158 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

[cnirbhay]

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...

@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?

[makkemal]

@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