ELASTIC-PLASTIC LARGE DEFLECTION ANALYSIS OF AXISYMMETRIC SHELLS.

This paper presents a finite element formulation for elastic-plastic large deflection analysis of axisymmetric shells. The doubly curved shell finite element used has been widely applied to linear elastic stress analyses and linear stability analyses by the present authors and their co-workers previously. Recently developed non-linear shell strain-displacement relations are used in place of the widely-used relations of Donnell or Sanders. For plastic analysis, a multi-layered approach is employed using the Prandtl-Reuss normal flow rule with isotropic hardening. An efficient and accurate state determination algorithm is adopted and demonstrated. The variable arc-length method is realized in the formulation by assuming incremental reversibility for plastic behavior, which facilitates an efficient iterative procedure for tracing both the pre- and post-critical load deflection path. Several examples are included to show the accuracy, efficiency and capability of the present formulation.