BeamCrossSectionDefinition for 1D elements

[nicoguaro]

Hello,

I used the FEM WB to find the vibration modes of a tuning fork. For the one in the image the frequency is 410.42

tuning_fork.png (76.3 KiB) Viewed 2521 times

that is close to the theoretical value of 407.98. Now I want to repeat this analysis for a tuning fork made of beam elements, where the geometry is made of lines. But I can't mesh it or assign the BeamCrossSection. Is this no supposed to work right now? If that's the case, what is needed to get this capabilities?


OS: Windows 7
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.6703 (Git)
Build type: Release
Branch: releases/FreeCAD-0-16
Hash: 2ce5c8d2e3020d05005ed71f710e09e9aa561f40
Python version: 2.7.8
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

[bernd]

Great to see you got good results. In the regard of beam FEM ...

Mesh:
The FEM internal mesher supports solid mesh only. You can use the Macro_GMSH. You need a wire to make a 1D mesh. To define a beam cross section add a object beam cross section and change the parameter in property editor. ATM only rectangular are supported. Calculix supports circular too, it would not a big deal to add.

Keep in mind ATM no beam should go in the direction of z. This needs special input in CalculiX which is not implemented. Ahh and I got wrong results with the 2nd order beam. There might be some issuse. As you see the beams still needs some love but except me noone has used them before. Would be cool if we could make a step forward in this regard.

bernd

[nicoguaro]

Great to see you got good results. In the regard of beam FEM ...

Mesh:
The FEM internal mesher supports solid mesh only. You can use the Macro_GMSH. You need a wire to make a 1D mesh. To define a beam cross section add a object beam cross section and change the parameter in property editor. ATM only rectangular are supported. Calculix supports circular too, it would not a big deal to add.

Keep in mind ATM no beam should go in the direction of z. This needs special input in CalculiX which is not implemented. Ahh and I got wrong results with the 2nd order beam. There might be some issuse. As you see the beams still needs some love but except me noone has used them before. Would be cool if we could make a step forward in this regard.

bernd

Can we put that information on the documentation? Also, what need to be done to make it easier?

[bernd]

circular section should be possible soon. viewtopic.php?f=17&t=15877

Can we put that information on the documentation? Also, what need to be done to make it easier?

Sure, feel free to help in extending FreeCAD FEM documentation ...