Optimal design of rigid-plastic cylindrical shells in the post-yield range

Abstract

An optimal design technique is developed for rigid-plastic cylindrical shells subjected to a distributed transverse pressure and a specified axial load. Moderately large deflections are taken into account and a deformation-type theory of plasticity is employed. The optimal design procedure results in a unified approach to optimization in the post-yield range. Necessary conditions for optimality are established by the aid of variational methods of the optimal control theory. Two examples are presented: (1) the optimal layout of rigid circular supports (stiffeners) is found which minimizes the mean deflection; (2) the optimal thickness distribution of a sandwich shell is established which corresponds to the minimum material consumption requiring the deflection of the design coinciding with that of the constant thickness shell.