Symmetry‐Guided Multifunctional Acoustic System Based on Mechanically Actuated Sonic Crystals

A mechanically actuated sonic crystal is designed, fabricated, and experimentally validated as a modular element for assembling a symmetry‐guided multifunctional acoustic platform. By selecting a specific underlying symmetry, we demonstrate that the number and type of achievable device functionalities can be rigorously determined within a unified group‐theoretical framework. In this work, we realize three out of the four predicted classes of devices—acoustic switch, controlled confined propagation, and beam splitter—by mechanically rotating unit cells composed of cylinders with embedded anisotropic C‐shaped inclusions (CSIs). Numerical simulations and experiments confirm the corresponding wave‐manipulation behaviors, while also validating the predictive power of the symmetry‐based classification. Finally, we provide a clear design route for implementing the remaining class, namely acoustic logic‐gate operations, completing the full set of functionalities supported by the chosen symmetry.