Noise pollution has become a significant global problem in recent years. Unfortunately, conventional acoustic materials cannot offer substantial improvements in noise reduction. However, acoustic metamaterials are providing new solutions for controlling sound waves, and have huge potential for mitigating noise propagation in particular. Recently, owing to the rapid development of acoustic metamaterials, metamaterials for acoustic noise reduction have drawn the attention of researchers worldwide. These metamaterials are often both light and compact, and are excellent at reducing low‐frequency noise, which is difficult to control with conventional acoustic materials. Recent progress has illustrated that acoustic metamaterials effectively control sound waves, and optimizing their structure can enable functionality based on new physical phenomena. This review introduces the development of acoustic metamaterials, and summarizes the basic classification, underlying physical mechanism, application scenarios, and emerging research trends for both passive and active noise‐reduction metamaterials. Focusing on noise reduction, the shortcomings of current technologies are discussed, and future development trends are predicted. As our knowledge in this area continues to expand, it is expected that acoustic metamaterials will continue to improve and find more practical applications in emerging fields in the future.

Acoustic Metamaterials for Noise Reduction: A Review

This study collects all of the existent papers in the field of acoustic transmission across multilayered plate constructions. Herewith, a comprehensive source is proposed wherein approximately 410 ...

Prediction of acoustic wave transmission features of the multilayered plate constructions: A review:

This study proposes the use of a linear and geometrically nonlinear inerter-based resonator in locally resonant acoustic metamaterials (LRAMs) and evaluates the performance on low-frequency wave attenuation. The LRAM is modeled as a 1D chain system composed of mass-in-mass unit cells connected by springs, and the geometrical nonlinearity is achieved by two lateral inerters linking the resonator and lumped mass symmetrically with respect to the horizontal springs. For the nonlinear inerter-based LRAM, the dispersion relation is analytically derived by a complex Fourier transform and the harmonic balance method. Compared with the linear inerter-based LRAM, the proposed nonlinear inerter-based structure has the property of a low-frequency bandgap with sufficient width for longitudinal wave propagation without being sensitive to changes in the inertance ratio. The nonlinearity can extend the original material parameter restrictions, leading to a lower-frequency bandgap. The results of dispersion properties are validated by wave transmittance and vibration power flow diagrams obtained by using the method of effective mass. It is shown that an adequate number of unit cells can achieve better wave attenuation performance.

https://aip.scitation.org/doi/pdf/10.1063/5.0084399

Enhanced suppression of low-frequency vibration transmission in metamaterials with linear and nonlinear inerters

A spectral dynamic stiffness (SDS) model for plate assemblies stiffened by beams is proposed. The theory is sufficiently general where the plate assemblies can be subjected to any arbitrary boundary conditions (BCs), but importantly, the beam stiffeners can be of open or closed cross-sections, and maybe connected to plates with or without eccentricity. First, by using modified Fourier series, the SDS formulations for different beam stiffeners are developed based on their equations of motion for the most general case. Then, the beam stiffeners’ SDS matrices are superposed directly onto those of the plate assemblies. Next, the reliable, efficient and robust Wittrick-Williams algorithm is applied for the modal analysis of the overall structure. Representative examples are provided to illustrate the accuracy and versatility of the method, where the proposed theory is extensively validated by the software ANSYS. The proposed method inherits all advantages of the previously developed SDS theory for plate structures, including high computational efficiency, accuracy, robustness in eigenvalue calculation and the versatility in modelling arbitrary BCs. The proposed theory extends the existing SDS theory substantially to cover a wide class of beam stiffened plate structures used in train bodies, ship hulls, aircraft fuselage and wings and many others.

Suchao Xie

Papers

A lightweight multilayer honeycomb membrane-type acoustic metamaterial