## fcFEM - FEA from start to finish

About the development of the FEM module/workbench.

Moderator: bernd

HarryvL
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### Re: fcFEM - FEA from start to finish

Wait that’s not right. This is a pit of 8x8x4m deep.
HarryvL
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Location: Netherlands

### Re: fcFEM - FEA from start to finish

Now 4x4x4m:

fcFEM_Pit_4x4x4.jpg (75.62 KiB) Viewed 394 times

fcFEM_Pit_4x4x4.png (36.66 KiB) Viewed 394 times

Trench_Collapse_4x4x4.png (208.92 KiB) Viewed 394 times

Now 38% stronger, but still not enough. This pit will collapse when reaching 3m depth or so.
bernd
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Location: Zürich, Switzerland

### Re: fcFEM - FEA from start to finish

yeah this is what I like ... real 3D excavations !
bernd
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### Re: fcFEM - FEA from start to finish

most engineering tools only allow 2D excavation and soil analysis.
bernd
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### Re: fcFEM - FEA from start to finish

HarryvL wrote:
Tue Mar 19, 2019 9:52 am
With as an obvious simplification:

Code: Select all

``````normal=stress[:3]
shear=stress[3:]
pressure=np.average(normal)
sig_mises=np.sqrt(1.5*np.linalg.norm(normal-pressure)**2+3.0*np.linalg.norm(shear)**2))
``````
there is one ")" to much above at the end ...

Code: Select all

``````
normal=stress[:3]
shear=stress[3:]
pressure=np.average(normal)
sig_mises=np.sqrt(1.5*np.linalg.norm(normal-pressure)**2+3.0*np.linalg.norm(shear)**2)
``````

like this: https://github.com/berndhahnebach/FreeC ... diff=split ?

I added a unit test lately. It still is ok The von mises test only coúld be run on linux with:

Code: Select all

``./bin/FreeCAD --run-test "femtest.testresult.TestResult.test_stress_von_mises"``
HarryvL
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Location: Netherlands

### Re: fcFEM - FEA from start to finish

Yes, like that . It looks more Pythonic and should be slightly faster.
bernd
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Location: Zürich, Switzerland

### Re: fcFEM - FEA from start to finish

HarryvL wrote:
Mon Mar 25, 2019 10:07 am
Yes, like that . It looks more Pythonic and should be slightly faster.
BTW: what is best to name the tuple for the 6 stress components. Ist stresstuple fine, or just stress (I don't like this), or stresstensor or whatever ? We gone make some use of it in femconcrete branch too. https://github.com/berndhahnebach/FreeC ... f6e4e5L473
PrzemoF
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### Re: fcFEM - FEA from start to finish

stress_tensor sounds fine. I don't like to name variables after type. If down the line you change the type for some reason you'll have to change variable name as well.
HarryvL
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Location: Netherlands

### Re: fcFEM - FEA from start to finish

I agree
bernd
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Location: Zürich, Switzerland