OPTEC - K.U.Leuven Center of Excellence: Optimization in Engineering

"A methodology for the optimal design of shell shaped structures" (WG4)
Saartje Arnout

In modern architecture, there is a tendency towards complex structures. These structures frequently have the shape of a classical shell. As the geometry of a shell plays a key role in its structural behaviour, this entails an increasing attention for the optimal design of shell structures.
Structural optimization is a very promising design tool. However, some crucial choices concerning the method, the design variables, the parametrization etc. have to be made to use it in practice, Therefore, a methodology is presented where optimization is applied throughout the design process to obtain an optimal final design. It is demonstrated how to use the available information in such a way that the results of the optimization are helpful in the current stage of the design process.
In the conceptual design stage, an initial design concept for the shape of the structure is usually available. However, no details about the structure are available. As a consequence, a simplified analysis model with only a small number of relevant load cases can be sufficient. This enables the use of global optimization algorithms. In general, the global optimum is targeted, corresponding to the least material use. Alternatively, the design space can be explored to see the variety of good or near-optimal solutions in the design space.
In later design stages, the overall geometry is fixed and large design changes have to be avoided. Consequently, local optimization algorithms maybe preferred. More details about the structure are known. Therefore, it is possible to implement the design criteria more strictly. In this stage, it can be necessary to account for uncertainties, such as initial geometrical imperfections of the shell structure. An optimization based on this detailed model with a limited design space can show the most efficient changes for reduction of the material volume.