Optimal design of a cylindrical shell under overall bending and axial force with respect to creep stability

Abstract

Optimal structural design of a noncircular cylindrical shell under overall bending and axial force is considered. The material is assumed to be governed by the Norton nonlinear steady creep law. Minimal cross-sectional area is the design objective, the middle line of the profile and the wall-thickness are the design variables and the constraints refer to local stability of the wall according to Gerard's criterion and to brittle creep rupture as described by the Kachanov-Robinson hypothesis. In view of bending, optimal design requires some concentrated areas (longitudinal ribs) located at the outer fibres of the cross-section.