Riassunto analitico
Engineering practice often highlights the necessity to improve the performance of a structure by decreasing its mass while preserving adequate stiffness and resistance. Traditional solutions solve the problem by adopting different materials with better properties. This is often not possible mainly because of the cost of materials. The question, then, is whether there is another way to improve the performance of a structure (in terms of strength and stiffness) while reducing the mass. The answer lies in the optimization processes. The term optimization is connected to the need to maximize or minimize certain quantities as long as certain constraints are not violated. The aim of this thesis is the application of structural optimization, in particular shape and topology optimization, to find the optimum design for sheet metal formed stiffening ribs. In particular, two different case-studies are analysed: the first, simpler, consisting of a thin rectangular sandwich panel; and the second, more complex, consisting of a thick general sandwich panel. The simplest case-study is also used for theoretical and analytical checks. Optistruct Altair Engineering has been chosen as the software used for the linear analysis and the optimization. In the first chapter an introduction of the thesis and the state of the art are presented. The second chapter is dedicated to structural optimization and deeply to shape and topology optimization. The third chapter focuses on the theory of sandwich panels. The four chapter deals with the analytic calculation of engineering quantities of the rectangular sandwich structures. The fifth chapter is dedicated to the modelling, the linear analysis, and the optimization of the case-studies in Altair Optistruct and Hyperstudy. This chapter can be subdivided into four macro areas: the modelling, the linear analysis of the structures, their optimization, and the verification of the obtained results with the intent of understanding if and how it is possible to apply optimization techniques in the preliminary phase of a project without having any engineering knowledge and without the possibility to control the results in terms of aesthetics and ergonomics. Chapter sixth concludes the thesis by reporting the achievements and limitations of the work.
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