Optimization of Shapes of Shell Structures using FEM as analysis tool

Abstract

The present work deals with arriving at the optimum shapes of structures with respect to thickness, shape, topology optimization treating them separately and also by combining them. The targets are achieved by integrating geometric modeling, structural analysis,sensitivity analysis and built-in optimization modules.The First part of the thesis aims on optimization based on hickness newlineand shape. The illustrative examples considered are the Shell structures newlineobtained by inverse technique, cylindrical shells and examples of straight and curved forms of box girder bridges. Inverse technique is the method in which the static analysis is performed and the hanging model is created from the deflection profile which in turn is inverted to get deflection free model as a first step of optimization. These inverse models are further optimized for various objective functions such as minimizing the structural volume, minimizing the weighted frequency etc as single newlineobjective optimization. Four cases of support conditions are considered for optimizing the respective inverse models. Cylindrical shells are considered for three cases of support conditions for the same objective functions. Structural Energy norms are calculated for each case and found to be within user specified limits. The second part of the thesis deals with the case of optimization, the topology optimization. This part of the thesis concentrates on optimum shapes of shell structures obtained by inverse technique for four support.