Design of multi-state tunable phononic crystals based on the reconstruction mechanism of guide-rail lattice

Abstract

Tunable acoustic wave design is essential in phononic crystals (PnCs) because acoustic waves constantly change in various frequency ranges during practical applications. In this study, we report a novel multi-state tunable PnC design method in which the lattice size is modified through a guide-rail lattice reconstruction mechanism. The scatterer design achieves the anticipated multi-state tunable functions via a non-gradient topology optimization method. Optimization problems were considered for two application contexts and the resulting design was verified with numerical simulations and experimental tests. The study found that the designs produced through the proposed technique were able to achieve the highly desired multi-state regulation while also enabling multi-path tuning. Furthermore, this technique does not require any special material requirements or complex deformations, and it does not rely on persistent external factors. It successfully achieves a predictable tunable bandgap for three states. In addition, the researchers discovered that tunable PnC resonators can introduce a defect band whose frequency changes along with the movable bandgap. This produces a multi-frequency localization effect that can aid in the advancement of acoustic energy harvesting.