Elastic energy in shells

Hi all,

I was performing shell analysis with Karamba. Especially, I am interested in the contributions of bending and axial energy to the total energy (by the way thank you to the team for this feature, it's very helpful!). I expected the sum of these two energies to be equal to the total energy.

E=E(bending)+E(axial)

This is true when linear analysis is performed, but the values can differ greatly (say 30%) when I perform second order analysis.

Do you have any thoughts on what would explain this?

Best,

Romain M.

Replies to This Discussion

Permalink Reply by Karamba3D on December 2, 2015 at 12:16am

Hi Romain,

thank you for your post. This is a bug in Karamba 1.1.0 which will be removed in the next release.

Best,

Clemens

Permalink Reply by Romain Mesnil on December 2, 2015 at 12:54am

Hi Clemens,

thanks for your answer.

Grüsse,

Romain

Permalink Reply by Tina Moikjær Harksen on June 19, 2016 at 2:56am

Hi Clemens and Romain

I have earlier been testing the deformation energy in cases of pure bending and pure axial forces, and it worked fine.
However, I don't seem to get as great results as Romain, when I use it in a proper shell.
I'll just attach an example of the values I get.
In all af my shells, my axial and bending energy of the same size, and they are seperately almost the same size as the total energy of the model.

I don't know if I've just interpreted the results wrong, but because the axial and bending energy do have different distributions.

Best

Tina

Attachments:

Deformation energy.PNG, 53 KB

Permalink Reply by Tina Moikjær Harksen on June 19, 2016 at 5:32am

Okay, I think I have found the problem, and it might be a bug.
In the example I posted before, the shell was loaded with gravity load.
In the attached, I applied the load as a mesh load instead, an the results seem more reasonable.

Attachments: