OPTIMUM BUCKLING DESIGN OF CYLINDRICAL STIFFENER SHELL UNDER EXTERNAL HYDROSTATIC PRESSURE

Abstract

This paper present an investigation of the collapse load in cylinder shell under uniform
external hydrostatic pressure with optimum design using finite element method via
ANSYS software. Twenty cases are studied inclusive stiffeners in longitudinal and ring
stiffeners. Buckling mode shape is evaluated. This paper studied the optimum design
generated by ANSYS for thick cylinder with external hydrostatic pressure. The primary
goal of this paper was to identify the improvement in the design of cylindrical shell under
hydrostatic pressure with and without Stiffeners (longitudinal and ring) with incorporative
technique of an optimization into ANSYS software. The design elements in this research
was: critical load, design variable (thickness of shell (TH), stiffener’s width (B) and
stiffener’s height (HF). The results obtained illustrated that the objective is minimized
using technique of numerical optimization in ANSYS with optimum shell thickness and
stiffener’s sizes. In all cases the design variables (thickness of shell) was thicker than the
monocoque due to a shell’s thicker is essential to achieve the strength constraints. It can be
concluded that cases (17,18,19, and 20) have more than 90% of un-stiffened critical load.
The ring stiffeners causes increasing buckling load than un-stiffened and longitudinal
stiffened cylinder.