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[alaettin.ozer]

Hi There,

I am trying to verify analytical approaches of buckling of clylindrical column with D=80mm L=1200mm of Johnson, Tetmajer with Finite element analysis in Ansys Workbench. This is an inelastic buckling. I made firts of all elastic buckling. After changed it to inelastic case. Nonlinear effects included. But load multipliers obtaned from latter analysis for this column very close to elastic analysis. And colculation of critical load does not fit analytical results. Material nonlineratiy (nonlinear effects) and large deflection are on. Keep pre stress load pattern is yes. The analytical results form Johnson and Tetmajer are for critical normal stress 213MPa and 241MPa but from calculation it is 540MPa. I tried 1N and 20e3N but still the same situation. Would you please help me. Where is the problem.

 

 

 

[alaettin.ozer]

I think the problem is this warning. This solution does not give correct one. In this topic "https://innovationspace.ansys.com/forum/forums/topic/large-deflection-warning-when-turned-on/" Peter mention about that. But now it is not correct. I need help of Peter :)

 

 

[dlooman]

I don't think that message is the issue.  Another way to do a non-linear buckling analysis is to simply run the static analysis with an applied displacement until buckling occurs.  A non-linear eigenvalue analysis is a buckling analysis is still linear in the sense that the analysis is done based on the model stiffness at the end of the static.  The static needs to have a load large enough to reach the plastic portion of the stress strain curve to be different from a linear eigenvalue analysis.