'A rectangular plate element' for ultimate strength analysis

摘要

In order to increase the safety of plated structures such as ships, strength analysis to the ultimate strength state should be performed taking into account of local failures of buckling and yielding of component plate elements. Direct application of the finite element method still needs enormous computation time and is not economical to use at the design stage, even most advanced computers are provided. In order to achieve this purpose, one of the authors proposed the "Idealized Structural Unit Method (ISUM)" and proved its usefulness by many applications developing many ISUM elements such as rectangular plate, stiffened plate, tabular beam-column and so on. In this paper, a new rectangular plate element is developed, which can analyze all stages of behaviors to ultimate strength such as elasto-plastic, buckling and post-buckling, taking into account initial deflection and residual stress. The deflection function is composed of selective eigen-functions with some parameters. Partial yielding of the element is dealt with a through-thickness plasticity condition. The stiffness of the element is calculated by numerical integration. Necessary computation time is very short for any aspect ratios and the accuracy is very high in comparison with FEM. This element is not only a new efficient rectangular ISUM element but also can be used for general purposes.