Boundary Conditions

[gkokotinis]

Is there a way to set as boundary condition four support points (for examble the four corners)?

[quaesito]

Yes, you could model is as follows:

• Create an external bc o-o-o-o with no constraints at the external boundaries
• Create 4 internal boundary conditions with 4 point supports

[gkokotinis]

This one creates supports to the entire edges. I need just the corners.

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On Mon, May 11, 2020 at 10:04 AM Michele De Filippo < ***@***.***> wrote: yes. Set: typeextBC = 's-s-s-s' — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#1 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/APQBWHWVS6I36VBNVUAYCNLRQ6PPZANCNFSM4M4CNO7A> .

[gkokotinis]

Hello again, I tried to create 4 point supports as you suggested with the external bc o-o-o-o, but the result is not the desirable one. Here I show you the resulting graph.  However, when I set 4 patch supports, the result is closer to reality. Which do you think could be the problem?

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On Mon, May 11, 2020 at 10:07 AM Michele De Filippo < ***@***.***> wrote: Yes, you could model is as follows: - Create an external bc o-o-o-o with no constraints at the external boundaries - Create 4 internal boundary conditions with 4 point supports — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#1 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/APQBWHTGFCKRK744NOZI2UDRQ6PZNANCNFSM4M4CNO7A> .

[quaesito]

Points supports are always tricky in fem for a few reasons.
Try with the following suggestion:
I suggest you create a finely meshed plate with external bcs o-o-o-o and 4 patch supports at the corners (like if they were columns). You can then reduce the size of the support (and accordingly make the mesh finer and finer), hence simulating you get closer to a point support. When your results are close to your expectations and you are satisfied with it, you have found your best configuration for the model.
Hope this will help!

[gkokotinis]

Ok, thank you very much!

[gkokotinis]

Hello again,

Subsequently, I am trying to change positions of the support patches and to calculate the new deformation. For example, if i "drag" the two left-edge corner supports to the middle of the edge, I am waiting to see a major deformation in z-direction. Any idea of how to do that?

[quaesito]

If I have correctly understood your problem, you want to reposition the two supports at the corners to the middle of the edge. Then, in that case, you should adjust the boundary conditions.

[gkokotinis]

I want to move the two supports, but to maintain the length of the edge. For example, if initially the edge's length was "a", I want to move the supports and the curve's length to be also "a" after that, but keeping the supports at the corners of my geometry. The result will be an extra deformation to z-axis. If I just change the position of the supports adjusting the boundary conditions, the result will be not to have supports at the corners, but somewhere else.