A method for the estimation of plastic buckling loads

Certain elastic-plastic buckling problems require the solution of an appropriate incremental or “rate” boundary-value problem in order that physically meaningful results may be obtained. In this paper, it is shown that a recent general variational theorem by Neale[8] may be advantageous for the approximate solution of such problems. As an example, the buckling of elastic-plastic cylindrical shells under torsion is analyzed, wherein the material is assumed to obey the incremental theory of plasticity and the effects of initial imperfections in geometry are taken into account.