A Review of Acoustic Metamaterials and Phononic Crystals

Liu, Junyi; Guo, Hanbei; Wang, Ting

doi:10.3390/cryst10040305

Cited by 173 publications

(80 citation statements)

References 87 publications

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“…Phononic crystal (PC) structures, known as periodic composite structures, exhibiting bandgaps with piezoelectric/piezomagnetic/magnetoelectric phases, have been investigated in recent years, which can find important applications in harmonic signal processing, vibration reducing, noise controlling, filtering, and other MEMS/NEMS devices [1][2][3][4][5][6][7][8][9][10]. The bandgap for elastic wave propagation arises from the Bragg scattering and local resonance [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Tunable Bandgaps in Phononic Crystal Microbeams Based on Microstructure, Piezo and Temperature Effects

Hong

Zhang

et al. 2021

Crystals

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A new model of non-classical phononic crystal (PC) microbeam for the elastic wave bandgap generation is provided, incorporating microstructure, piezomagnetism, piezoelectricity and temperature effects. The wave equation of a general magneto–electro–elastic (MEE) phononic crystal microbeam is derived, which recovers piezoelectric- and piezomagnetic-based counterparts as special cases. The piezomagnetic and piezoelectric materials are periodically combined to construct the PC microbeam and corresponding bandgaps are obtained by using the plane wave expansion (PWE) method. The effects of the piezomagnetism, piezoelectricity, microstructure, geometrical parameters and applied multi-fields (e.g., external electric potential, external magnetic potential, temperature change) on the bandgaps are discussed. The numerical results reveal that the bandgap frequency is raised with the presence of piezo and microstructure effects. In addition, the geometry parameters play an important role on the bandgap. Furthermore, large bandgaps can be realized by adjusting the external electric and magnetic potentials at micron scale, and lower bandgap frequency can be realized through the temperature rise at all length scales.

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Section: Introductionmentioning

confidence: 99%

Tunable Bandgaps in Phononic Crystal Microbeams Based on Microstructure, Piezo and Temperature Effects

Hong

Zhang

et al. 2021

Crystals

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“…These bandgaps can be broadly classified in two physical mechanisms: Bragg scattering [ 1 ] and local resonance [ 2 , 3 , 4 ]. In general, the Bragg-type bandgaps occur at wavelengths in the direction of sound wave propagation with the same order of magnitude as the lattice size and require large lattice constants [ 5 ]. On the other hand, locally resonant bandgaps correspond to internal resonances due to the microstructure, and they can be generated using resonators [ 6 , 7 , 8 , 9 , 10 , 11 ].…”

Section: Introductionmentioning

confidence: 99%

2D Dynamic Directional Amplification (DDA) in Phononic Metamaterials

2021

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Phononic structures with unit cells exhibiting Bragg scattering and local resonance present unique wave propagation properties at wavelengths well below the regime corresponding to bandgap generation based on spatial periodicity. However, both mechanisms show certain constraints in designing systems with wide bandgaps in the low-frequency range. To face the main practical challenges encountered in such cases, including heavy oscillating masses, a simple dynamic directional amplification (DDA) mechanism is proposed as the base of the phononic lattice. This amplifier is designed to present the same mass and use the same damping element as a reference two-dimensional (2D) phononic metamaterial. Thus, no increase in the structure mass or the viscous damping is needed. The proposed DDA can be realized by imposing kinematic constraints to the structure’s degrees of freedom (DoF), improving inertia and damping on the desired direction of motion. Analysis of the 2D lattice via Bloch’s theory is performed, and the corresponding dispersion relations are derived. The numerical results of an indicative case study show significant improvements and advantages over a conventional phononic structure, such as broader bandgaps and increased damping ratio. Finally, a conceptual design indicates the usage of the concept in potential applications, such as mechanical filters, sound and vibration isolators, and acoustic waveguides.

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“…Unsurprisingly, many mechanical metamaterials can be considered as successors of cellular materials [ 14 , 15 ]. Indeed, the unconventional properties of mechanical [ 16 , 17 , 18 ], elastic [ 19 , 20 , 21 , 22 , 23 ], and acoustic metamaterials [ 24 , 25 ] originate in their intrinsic periodicity, along with the rational design of unit cells.…”

Section: Introductionmentioning

confidence: 99%

“…While for engineering materials loss of stability is usually unwanted, on par with failure or delamination, for functional metamaterials, loss of stability can be frequently harnessed to control their unconventional properties [26][27][28][29][30][31]. The elastic instabilities were used to adjust the stiffness or auxeticity of structured materials [25,32], open and close elastic bandgaps [33], and realize other unusual wave phenomena [34]. Adding a soft deformable matrix into the design facilitates extra coupling between stiff components, enabling more Materials 2021, 14, 2038 2 of 13 involved buckling behavior accompanied by the formation of various instability-driven patterns [35,36].…”

Section: Introductionmentioning

confidence: 99%

The Emergence of Sequential Buckling in Reconfigurable Hexagonal Networks Embedded into Soft Matrix

2021

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The extreme and unconventional properties of mechanical metamaterials originate in their sophisticated internal architectures. Traditionally, the architecture of mechanical metamaterials is decided on in the design stage and cannot be altered after fabrication. However, the phenomenon of elastic instability, usually accompanied by a reconfiguration in periodic lattices, can be harnessed to alter their mechanical properties. Here, we study the behavior of mechanical metamaterials consisting of hexagonal networks embedded into a soft matrix. Using finite element analysis, we reveal that under specific conditions, such metamaterials can undergo sequential buckling at two different strain levels. While the first reconfiguration keeps the periodicity of the metamaterial intact, the secondary buckling is accompanied by the change in the global periodicity and formation of a new periodic unit cell. We reveal that the critical strains for the first and the second buckling depend on the metamaterial geometry and the ratio between elastic moduli. Moreover, we demonstrate that the buckling behavior can be further controlled by the placement of the rigid circular inclusions in the rotation centers of order 6. The observed sequential buckling in bulk metamaterials can provide additional routes to program their mechanical behavior and control the propagation of elastic waves.

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A Review of Acoustic Metamaterials and Phononic Crystals

Cited by 173 publications

References 87 publications

Tunable Bandgaps in Phononic Crystal Microbeams Based on Microstructure, Piezo and Temperature Effects

Tunable Bandgaps in Phononic Crystal Microbeams Based on Microstructure, Piezo and Temperature Effects

2D Dynamic Directional Amplification (DDA) in Phononic Metamaterials

The Emergence of Sequential Buckling in Reconfigurable Hexagonal Networks Embedded into Soft Matrix

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