Buckling cellular structures - negative eigenvalues
Buckling cellular structures - negative eigenvalues
(OP)
I'm investigating buckling of cellular structures and started off with a simple two-cell case which worked as expected. I've started effectively building up combinations of these two cell units but even by the time I get to a six-cell structure I get negative eigenvalue results. Whenever this problem has arisen in the past it has been because I have had insufficient restraints, resulting in a rigid body motion at some point, but that doesn't seem to be the case now. Given that I'm building up from a model which does work as expected and is adequately restrained, I'm confused as to what is going wrong.
Any advice welcome.
Thanks.
Any advice welcome.
Thanks.





RE: Buckling cellular structures - negative eigenvalues
Negative eigenvalues and their associated eigenvectors are simply valid "mathematical solutions" to the eigen problem and can be safely ignored as they are usually of no real world significance.