On 7th September 2020 David Roca has successfully defended his PhD Thesis titled "Numerical Tools for Computational Design of Acoustic Metamaterials" in the framework of Mechanical, Fluid and Aeronautical Engineering Programme. The thesis was carried out at the Technical University of Catalonia (UPC) under the supervision of Profs. Juan Carlos Cante and Oriol Lloberas.
The conception of metamaterials as artificially designed structures to obtain a set of properties that are not achievable in materials in a natural way has caught the attention of the scientific and industrial communities. Within the wide range of applications that can be given to metamaterials, focusing on the field of acoustics, the possibility of creating a material capable of effectively attenuating noise in specific frequency ranges is of great interest in multitude of industries. In this context, the so-called Locally Resonant Acoustic Metamaterials (LRAMs) stand out for the possibility of designing their internal topology so that they produce high levels of attenuation in specific regions of the frequency spectrum. With an optimal topological design, LRAMs can be used, for example, for the construction of lightweight sound-insulating panels, which operate in low-frequency ranges, in which the classical solution requires materials of high density and thickness.
Given the importance of the topological structure of acoustic metamaterials in obtaining the desired properties, it is convenient to use leading numerical methods for the development of a set of computational tools aimed at analysis and design of optimal solutions. Such tools are based on three pillars: (1) the multiscale homogenization of complex material structures at a micro scale that results in obtaining effective properties that allow describing the behavior of the material at a macro scale, (2) techniques of reduction to minimize computational effort while maintaining sufficient levels of accuracy and (3) topological optimization methods used to obtain optimal configurations given a set of constraints and properties of the target material. These computational tools can be applied to the design of acoustic metamaterials that are efficient and practical at the same time, that is, that behave according to design specifications and are easily manufacturable, for example, using state-of-the-art 3D printing techniques.