Σχεδιασμός μικροδομής ευφυών υλικών και κατασκευών με χρήση βελτιστοποίησης ; Design of microstructure of smart materials and structures using optimization

The main purpose of the present Ph.D thesis is the development of methods and techniques for the proper design of structures affected by dynamic phenomena. Damping filters are among the most significant elements in engineering, since dynamic loadings are more complex than the static ones. Thus, the main idea of the present thesis is the development and analysis of tools that are going to lead to the design of prototypes capable of dealing with such dynamic phenomena on a structure. The first goal is the structural modeling using the Finite Element Method (FEM) for dynamic and static problems, mostly in the frequency domain, where the dynamic behavior of the structures on more than one frequency can be studied. Thus, several structures for attenuation on specific frequencies can be designed. Many challenges of the dynamic behavior are need to be faced and for this reason several technics for a big frequency range are studied. More specifically, a method based on Bloch theorem has been developed. This method study the wave propagation in a solid structure as well as the attenuation of the signal. Based on the Bloch theorem, several tools for the increase of the band gaps that do not allow the wave propagation have been developed. In order to achieve that, various parametric changes had to be made. These changes allow the study of the influence on the wave propagation in a structure, for example, during the change of the geometry of the structure, when material properties are altered, etc. Moreover, this technique allows the use of metamaterials with auxetic properties or the connection of the structure with smart materials, like piezoelectric patches, and with external electronic circuits. Finally, the requirements for the use of new methods and cutting edge technology on the engineering field are high. For this reason, classical optimization methods as well as topology optimization algorithms have been developed in order to create the optimum structures that are able to be produced by new methods like additive ...