Tunable superior sound absorber design with nested hexagonal tracks.

We propose a design of a tunable superior absorber based on the resonance absorption in underwater acoustic metastructure with nested hexagonal tracks. The structure comprises 37 hexagonal-shaped cells formed by two models depending on the formula for hexagonal numbers. Model I is labyrinthine acoustic metastructure (LAM), and model II is labyrinthine acoustic metastructure with a coil-up channel (LAMC). The results of model II demonstrate the achievement of a highly efficient sound absorber, with a maximum value of 0.999, within the frequency range of 130 Hz by rotating the third aperture at an angle of 180°. The effect of dissipative loss could be achieved by carefully controlling nested hexagonal tracks to achieve perfect absorption. Our research on tunable acoustic metastructure with absorbing properties has significant implications for engineering applications, particularly in noise mitigation. Our findings demonstrate the potential of these metastructures to provide tunable functionality, high efficiency, perfect absorption, and ease of construction, all within a compact design. [ABSTRACT FROM AUTHOR]