Buckling Behavior of Shells

i'm trying to evaluate the mechanical behavior of a shell structure. For this purpose i'm running an AnalyseTh.II.O and afterwards an analysis BModes for getting the buckling modes and the buckling load factor.

As my shell is basically parametrized by two variables, i'm searching the optimal combination of these two regarding buckling and elastic energy.

For 95% of the combinations tested, the buckling analysis is running without any issue and is giving back the critical load factor. There are some cases in which the structure buckles and i'm getting back a load factor 0. But for a small number of combinations, the analysis is running without giving back any value at all, neither any notification.

I tried to change the mesh density which solved the problem for a few cases but not for all. Any ideas what's this problem due to?

I would really appreciate any help.

Replies to This Discussion

Permalink Reply by Marco Pellegrino on November 10, 2015 at 12:13pm

Hi Christiane, try to set a less number in the convergence.

Permalink Reply by Karamba3D on November 10, 2015 at 12:58pm

Hi Christiane,

I think the problem is the Mises Iteration which is currently used for calculating the buckling factors. In the next version of Karamba (1.1.2.) a different, more stable algorithm will be used. A workaround might be to slacken the convergence criteria by setting 'Eps' to a larger number than 1E-7.

Best,

Clemens

Permalink Reply by Christiane Richter on November 12, 2015 at 4:10pm