Boundary conditions for a grid tube under combined loading

[Vigardo]

Dear experts,

I´m trying to model in ANSYS Mechanical (v14.5) the linear buckling behavior of a cylinder made of BEAM4 elements under combined loading (axial compression and bending moment) applied at the ends.

How should I set up the boundary conditions of a cylinder to keep rigid the ends while allowing their motion under both compressive force and moment?

After rigidifying one end of a cylinder made of BEAM4 elements with the CERIG command (CERIG,P) I´ve found confusing results: the buckling modes under combined loading are equal to the modes obtained only under pure axial compression. All nodes from the other end were fully clamped. I think that I successfully selected master and slave nodes and that the results from the initial static analysis seem ok, i.e. the moment applied at the master node node leads to some curvature and the axial force to some compression while the end nodes keep rigid.

What am I doing wrong? Any comments would be highly appreciated.

Thanks a lot in advance!

 

[Greg Bernhardt]

Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?