Shape optimization of shell structures by sensitivity analysis

ABSTRACT Ph.D. Thesis SHAPE OPTIMIZATION OF SHELL STRUCTURES BY SENSITIVITY ANALYSIS Habib UYSAL Atatürk University Graduate School of Natural and Applied Sciences Department of Civil Engineering Advisor: Prof. Dr. Rüstem GÜL Co-Advisor: Prof. Dr. Ümit UZMAN In this study, a computer program is developed using finite element method for the shape optimization of shell structures that is very common in engineering, and several examples are provided. The shape optimization program is implemented by a job control language and a finite element program, ANSYS, is used for structural analysis. The shape optimization program optimizes structures by allowing nodal movements. The vertical direction coordinates of some nodes in the finite element mesh are taken as design variables and under some constrains the minimization of structural weight is performed. Emphasis is made on a special modelling technique which overlays the design model onto an already existing finite element model. To achieve the shape optimization, different principles such as structural analysis, automatic mesh generation, sensitivity analysis and mathematical programming are interrelated. Different program modules are developed for each principle and communication between these principles are controlled by a job control language. This program, which is developed in order to verify the shape optimization of the shells, is designed for a general purpose and can be applied to variety of problems with some little modifications. Various shells under different loading conditions are optimized with this shape optimization program. 2002, 132 pages Key words: Shape optimization, shell structures, sensitivity analysis, finite element and linear programming. u