Search for: All records

Abstract This broad review summarizes recent advances and “hot” research topics in nanophononics and elastic, acoustic, and mechanical metamaterials based on results presented by the authors at the EUROMECH 610 Colloquium held on April 25–27, 2022 in Benicássim, Spain. The key goal of the colloquium was to highlight important developments in these areas, particularly new results that emerged during the last two years. This work thus presents a “snapshot” of the state-of-the-art of different nanophononics- and metamaterial-related topics rather than a historical view on these subjects, in contrast to a conventional review article. The introduction of basic definitions for each topic is followed by an outline of design strategies for the media under consideration, recently developed analysis and implementation techniques, and discussions of current challenges and promising applications. This review, while not comprehensive, will be helpful especially for early-career researchers, among others, as it offers a broad view of the current state-of-the-art and highlights some unique and flourishing research in the mentioned fields, providing insight into multiple exciting research directions. 

Metamaterials have offered unprecedented potentials for wave manipulations. However, their applications in underwater acoustic wave control have remained largely unexplored. This is because of the limited material choices and the lack of reliable fabrication techniques for the complicated structures. Herein, a metamaterial with microlattice structures as the building blocks is proposed for underwater operations. By designing the building blocks of the metamaterial and assembling them in a layered fashion, anisotropy is embedded in the structure, which results along different effective sound speeds in orthogonal directions. The designed metamaterial is fabricated by metal additive manufacturing using aluminum and steel. Experiments are performed using a resonator tube to evaluate its performance in water. An anisotropy ratio of around 2 is achieved, which is in good agreement with numerical simulations. The proposed metamaterial provides an effective means for underwater sound control with reduced fabrication difficulties and increased service life.