[Workbench] Nonlinear buckling 1

[marmilew]

Hi all

I analyse buckling stability of a column in a static, nonlinear analysis. Bottom support allows only rotations (except torsional) and top one allows rotations and vertical displacement. To get initial imperfection i apply lateral pressure in the 1st step. In the 2nd step lateral pressure continue and vertical, compresive force is applied.

For initial guess I started with lateral load of 100N/mm which gave me a lateral deflection of 12mm. Analysis converged. However, when i applied smaller pressure to have initial deflection of only 1mm, analysis cannot converge.

Can anyone explain, why analysis converge with bigger deformation and abort with the smaller one. With bigger deformation my structure is in theory less stable, however it converge better.

I use beam elements.

 

[rickfischer51]

What was the reason for non-convergence? I think a smaller lateral load would result in a higher buckling load, which means you could get convergence issues from other than structural instability, such as excessive element distortion, excessive plastic strain increment, etc.

Rick Fischer
Principal Engineer
Argonne National Laboratory

 

[marmilew]

Hello, thank you fro response.

How can i check plastic strains or distortion in beam element. It works in shell or solids, but not in beams.

 

[rickfischer51]

look at your .err and .out files. They will have warning and error messages.

Rick Fischer
Principal Engineer
Argonne National Laboratory

 

[marmilew]

Thank you