Abstract:
Acoustic metamaterials represent an exciting frontier in the control of waves and vibrations. The precise control of acoustic waves is fundamental for key technological applications, ranging from sound insulation to ultrasonic detection. In this work, the design, modeling, and analysis of novel two-dimensional phononic crystal (PnC) structures that integrate the architecture of auxetic materials are addressed. The objective is double: to create new structures capable of generating and controlling wide and tunable phononic bandgaps (PBGs), and to control the direction of energy flow and the propagation of acoustic waves. The study relies on the Finite Element Method (FEM) and the rigorous application of the Floquet-Bloch theory for the calculation of dispersion relations. We introduce and analyze two specific auxetic architectures derived from star-shaped honeycomb structure:
the concave circular-headed structure and the Arabesque structure. A parametric study is performed on the geometric variables to optimize structural and vibrational performances. The results obtained not only confirm the auxetic behavior of these designs but demonstrate their excellent ability to open robust complete PBGs. By exploiting Iso Frequency Contours (EFCs), we have modeled the phenomenon of self-collimation. This mechanism proves that these PCs can naturally focus and guide vibrational energy along precise trajectories, offering a promising trajectory for the unconventional manipulation of waves. This project opens concrete prospects for the development of high-precision acoustic insulation and filtering devices.
