Deformation-driven membrane-type acoustic metamaterials for tunable sound absorption: A combined experimental and numerical study

In recent years, membrane-type acoustic metamaterials (MAMs) have demonstrated considerable potential for low-frequency noise control. Nevertheless, their practical application in dynamic environments with time-varying noise frequencies remains constrained by limited tunability. Furthermore, the underlying mechanisms governing the acoustic behavior and tunability of MAMs are not yet fully understood, hindering the formulation of robust design methodologies. To overcome these limitations, this study introduces a tunable MAM featuring a simple yet effective adjustment strategy. The proposed design comprises a membrane with embedded mass blocks, a centrally positioned retractable rod, and a back cavity. By controllably inducing out-of-plane deformation in the membrane via the retractable rod, the system enables adjustment of membrane prestress, thereby achieving tunable sound absorption performance. To elucidate the working principle of such a practical adjustment strategy, a tailored finite element (FE) analysis framework is established, integrating coupled structural–acoustic domains and accounting for geometric nonlinearity in acoustic response. The validity of this framework is rigorously confirmed through impedance tube experiments. The analysis reveals that at the frequencies where sound absorption peaks, the surface impedance of the MAM matches the characteristic impedance of air. This results in the acoustic siphon phenomenon, enabling efficient conversion of sound energy into the system’s elastic strain energy. Leveraging this high-fidelity model, parametric investigation is further conducted to elucidate the effect of key factors on sound absorption performance, offering new insights for the design and analysis of tunable MAMs.