
Re: Mapping buckled mode shape into mesh for non linear buckling analysis
Janko Stellaard Sep 3, 2015 6:25 AM (in response to Stephen Callegari)Hi Steve,
Interesting question. I don't think it is possible in SW Sim unless you apply a force that activates the buckling in the desired direction. Maybe you could try to check the eigenfreq in a frequency study. Buckling should occur when the eigenfreq is equal to zero. Would be trial and error though.
I cant help you with literature.
Janko Stellaard
Cadmes BV
The Netherlands

Re: Mapping buckled mode shape into mesh for non linear buckling analysis
Stephen Callegari Sep 4, 2015 5:38 PM (in response to Stephen Callegari)Janko,
Thanks for the reply. Apparently, this technique is pretty robust.
As I am sure you aware, the issue with nonlinear buckling is we need a "small"
disturbance in geometry or load to induce the buckling process.
The reason for this is, our FEA geometry is "perfect" and in reality the geometry is not.
Also, the "perfect" FEA geometry and loading needs a "kickstart" to the buckling process.
Ovality in pipe, eccentricity of loads, and other manufacturing defects all contribute to an imperfect geometry or load
which causes the structure to buckle sooner than if modeled with a linear buckling analysis with perfect geometry.
The question then is how much disturbance load is required to design for non linear buckling.
We dont want too large or too small of a disturbance.
There are a couple of workarounds for applying the "disturbance" I am testing based on a literature search as follows:
1. Apply a lateral load (to induce buckling) with a magnitude of 0.50% of the buckling load found the eigenvalue (linear) buckling solution.
2. Apply a lateral load such that the deflection by the lateral load is equal to ~L/300. Where L is the unsupported span.
Does anyone have any comments or suggestions?
Steve