Simplified Ultimate Strength Evaluation Method of Rectangular Plates under Combined Loads

Abstract

The estimation of buckling strength of plates and stiffeners as a basic component of ship structures is very important to evaluate her safety. As for plates, recent classification rules consider the compressive ultimate strength, which is beyond elastic buckling strength, as their buckling criteria because the elastic bucking strength of plates likely gives over-conservative strength especially for thin plates.

The previous research developed many kinds of ultimate strength evaluation methods, which often adopted so called “curve fitting" technique to reflect the results of model experiments and/or non-linear FEM. Therefore, the methods might be affected by specific boundary conditions, initial deflection and residual stresses where the experiments and FEM were performed. To seek for the approaches with clearer physical backgrounds, the authors have developed a simplified method to evaluate ultimate strength of a rectangular plate subjected to combined loads. The method employs the elastic large deflection theory and Mises's yield criteria without using any “curve fitting" techniques. This paper discusses how to develop the elastic large deflection analysis to represent actual buckling behavior of plates using closed formula and how to judge the plate collapse with using yield functions, and then shows the accuracy of the developed method through a comparison with the results of non-linear FEM.