*INITIAL CONDITIONS, TYPE=STRESS error

About the development of the FEM module/workbench.

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boreilly
Posts: 26
Joined: Wed Apr 11, 2018 6:22 pm

Re: *INITIAL CONDITIONS, TYPE=STRESS error

Postby boreilly » Tue May 15, 2018 3:02 pm

Harry thanks very much, It looks great I will take some time to study and get back to you soon,

Regards,
Barry. :D
boreilly
Posts: 26
Joined: Wed Apr 11, 2018 6:22 pm

Re: *INITIAL CONDITIONS, TYPE=STRESS error

Postby boreilly » Sun Jun 10, 2018 2:33 pm

Hi Harry, I am having trouble cutting a plane through my cube. Please see attached file. I use Post Pipeline from result and Cut filter (you mentioned Warp filter was not working before). Am I missing a step. I'm trying to view Von Misses stress down the centre of the cube.
Any help gretly appreciated. :D
Attachments
CNT-Cu Simulation.FCStd
(513.79 KiB) Downloaded 17 times
UR_
Posts: 944
Joined: Tue Jan 03, 2017 8:42 pm

Re: *INITIAL CONDITIONS, TYPE=STRESS error

Postby UR_ » Sun Jun 10, 2018 4:51 pm

boreilly wrote:
Sun Jun 10, 2018 2:33 pm
Am I missing a step
It's sometimes a good idea to make everything invisible, except object of interest (in your case "Clip") ;)
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HarryvL
Posts: 1042
Joined: Sat Jan 06, 2018 7:38 pm

Re: *INITIAL CONDITIONS, TYPE=STRESS error

Postby HarryvL » Sun Jun 10, 2018 7:17 pm

boreilly wrote:
Sun Jun 10, 2018 2:33 pm
Hi Harry, I am having trouble cutting a plane through my cube. Please see attached file. I use Post Pipeline from result and Cut filter (you mentioned Warp filter was not working before). Am I missing a step. I'm trying to view Von Misses stress down the centre of the cube.
Any help gretly appreciated. :D
As @UR_ says ... simply select the pipeline in the Object Panel and press the space bar. :)
boreilly
Posts: 26
Joined: Wed Apr 11, 2018 6:22 pm

Re: *INITIAL CONDITIONS, TYPE=STRESS error

Postby boreilly » Tue Jul 03, 2018 5:42 pm

Hi Harry.
I am trying to model a basic CMOS device consisting of a silicon substrate with a Source and Drain region which are made of Silicon Germanium.
Due to the lattice mismatch between the silicon and the silicon germanium a compressive stress is developded in the silicon between the source and drain regions.
The lattice mismatch induces a 4.1% strain. To mimick this strain a temperature constraint is applied to the source and drain regions, the silicon is left alone.

I keep getting the following error:
Result node numbers are not equal to the mesh
boreilly
Posts: 26
Joined: Wed Apr 11, 2018 6:22 pm

Re: *INITIAL CONDITIONS, TYPE=STRESS error

Postby boreilly » Tue Jul 03, 2018 5:46 pm

Hi Harry.
I am trying to model a basic CMOS device consisting of a silicon substrate with a Source and Drain region which are made of Silicon Germanium.
Due to the lattice mismatch between the silicon and the silicon germanium a compressive stress is developded in the silicon between the source and drain regions.
The lattice mismatch induces a 4.1% strain. To mimick this strain a temperature constraint is applied to the source and drain regions, the silicon is left alone.

I keep getting the following error:
"Result node numbers are not equal to the Fem mesh nodecount"

I am trying to figure out this error.
Please see attached file, any help much appreciated.

Regards,
Barry.
Attachments
CMOS.FCStd
(768.67 KiB) Downloaded 12 times
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HarryvL
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Joined: Sat Jan 06, 2018 7:38 pm

Re: *INITIAL CONDITIONS, TYPE=STRESS error

Postby HarryvL » Wed Jul 04, 2018 12:53 am

Hi Barry, I had the same issue with your model. Your displacement boundary conditions are not right (two rigid body DOF remain ... vertical and a rotation along the line connecting the 2 supports), but that is not the root cause of the issue. I suspect the issue is with the material cards, but am not sure. I rebuilt your model from scratch (attached) and do get it to run. However the results are wrong. As can be seen from the picture below, I have two major issues ... 1) the surface temperature applied to source and drain only affects one of them and 2) the displacement boundary conditions are not properly taken into account. I chose the latter such that only rigid body motions are constrained (allowing free expansion). However, as can be seen from the results, spurious deformations occur at the supports. I may have made a mistake in the input, so attach the file for others to give it a go.


CMOS_1.png
CMOS_1.png (314.77 KiB) Viewed 218 times
-
CMOS_2.fcstd
(504.79 KiB) Downloaded 10 times


OS: Ubuntu 16.04.4 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.13959 (Git)
Build type: Unknown
Branch: master
Hash: 2f18182b6dff87f8857787c854e39ca4d441f993
Python version: 2.7.12
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.1.0
Locale: English/UnitedStates (en_US)
User avatar
HarryvL
Posts: 1042
Joined: Sat Jan 06, 2018 7:38 pm

Re: *INITIAL CONDITIONS, TYPE=STRESS error

Postby HarryvL » Wed Jul 04, 2018 1:16 am

,,, and this is what happens when I merge the two material objects for the source and drain into one, leaving the material properties unchanged


CMOS_2.png
CMOS_2.png (328.46 KiB) Viewed 217 times
-
CMOS_2.fcstd
(511.84 KiB) Downloaded 10 times

PS: I get the same result with my windows version of FC:

OS: Windows 7
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13522 (Git)
Build type: Release
Branch: releases/FreeCAD-0-17
Hash: 3bb5ff4e70c0c526f2d9dd69b1004155b2f527f2
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: English/Malaysia (en_MY)
boreilly
Posts: 26
Joined: Wed Apr 11, 2018 6:22 pm

Re: *INITIAL CONDITIONS, TYPE=STRESS error

Postby boreilly » Wed Jul 04, 2018 6:32 am

Hi Harry, thanks very much for your time and feedback, much appreciated. :D
I was thinking the FEM Constraint temperature needs to be applied at the interface between the Source/Drain and Silicon, however some of these are hidden. I tries to set the transparency of the silicon to 50 but to no avail. I also tried invrasing the size of the model x 10 but still no change. :cry:
I will continue to troubleshoot.

Regards,
Barry.
boreilly
Posts: 26
Joined: Wed Apr 11, 2018 6:22 pm

Re: *INITIAL CONDITIONS, TYPE=STRESS error

Postby boreilly » Wed Jul 04, 2018 7:04 am

Hi Harry,
There is something bigger going on here, When I run my other simulations now I am now getting the same error and get the same results as with the CMOS model. Is it something to do with the recompute button- I may have hit off it, else my Freecad has become corrupt. :cry:

Regards,
Barry.