Laurie Hartley wrote: ↑Sat Feb 11, 2023 4:40 am
...
Another thing that I don't understand is why the outer end of the frame to which the force of 76420 N (7.8 tonnes
) is applied is not displaced in the vertical direction as there is no restraint to the Z axis.
Thanks for the video!
Running a buckling or frequency analysis is based on a different mathematical approach than
running a static analysis. The resulting buckling or eigenfrequency shapes of the structure must not necessarily correspond
with the static deformation. When ramping up the max slider to 1000000 you can see that there is a vertical deformation,
but compared to the buckling shape of the flanges it is very small.
You can account for preloading by adding a "static-step" and the parameter "perturbation" to the input-deck,
see txt files in zip. The preloading results in a drop of the buckling factors.
I ran a stability analysis with a UPE-100 profile and compared the results to Euler-theory and the DIN-manual.
There are huge differences in the system-utilization. Euler gives 25%, DIN-manual 40%!
Dont trust FEM alone... See also files in zip.
What totally confuses me is the fact, that the results depending on the number of cpu I activate.
I tested the UPE-100 calculation on two different machines (intel i5 + i7 with 2 and 6 cores).
When using 6 cores on i7, I get these odd buckling shapes below the first correct eigenvalue.
- multi_cpu.JPG (116.35 KiB) Viewed 1400 times
EDIT:
UPE-100 calculation was done with FC0.20.2 stable release portable
Code: Select all
OS: Windows 10 Version 2009
Word size of FreeCAD: 64-bit
Version: 0.20.2.29177 +426 (Git)
Build type: Release
Branch: (HEAD detached from 0.20.2)
Hash: 930dd9a76203a3260b1e6256c70c1c3cad8c5cb8
Python 3.8.10, Qt 5.15.2, Coin 4.0.1, Vtk 8.2.0, OCC 7.6.3
Locale: German/Germany (de_DE)
Installed mods:
* BIM 2021.12.0
* CfdOF 1.21.3
* Curves 0.5.8
* Defeaturing 1.2.0
* dodo
* fasteners 0.4.4
* Manipulator 1.4.9
* Plot 2022.4.17
* Reinforcement
* WorkFeature