Design Proposals for Torsional Buckling of Stiffeners

摘要

The ability to predict torsional instability in the early stages of design can have important consequences on the design of both conventional and high performance ships. This thesis develops fast approximate methods of torsional buckling analysis for particular application in the concept, feasibility, and preliminary stages of ship design. Two simplified models of stiffeners commonly used in ship construction were presented. The first was an ideal I section stiffener. The second, a flat bar stiffener, which was included in this analysis because of its favorable productional properties and wide usage. These models, with initial imperfections, were subjected to axial compressive end loading and the resultant behavior analyzed. The approach of the analysis of this thesis was an application of the energy method to determine the critical buckling stress instead of the more commonly used equilibrium approach. Both beam theory and thin plate theory were used in energy-work relationships in these derivations. Then the first yield load was determined utilizing the Perry-Robertson approach. Integrated into all phases of this exploration was the concept of the geometric imperfections of the stiffeners. (Author)