Phononic crystals (PCs) and metamaterials (MMs) can exhibit abnormal properties, even far beyond those found in nature, through artificial design of the topology or ordered structure of unit cells. This emerging class of materials has diverse application potentials in many fields. Recently, the concept of tunable PCs or MMs has been proposed to manipulate a variety of wave functions on demand. In this review, we survey recent developments in tunable and active PCs and MMs, including bandgap and bandgap engineering, anomalous behaviors of wave propagation, as well as tunable manipulation of waves based on different regulation mechanisms: tunable mechanical reconfiguration and materials with multifield coupling. We conclude by outlining future directions in the emerging field.

Tunable and Active Phononic Crystals and Metamaterials

Research and applications of viscoelastic vibration damping materials: A review

Achieving vibration and/or wave attenuation with locally resonant metamaterials has attracted a great deal of attention due to their frequency dependent negative effective mass density Moreover, adaptive phononic crystals with shunted piezoelectric patches have also demonstrated a tunable wave attenuation mechanism by controlling electric circuits to achieve a negative effective stiffness In this paper, we propose an adaptive hybrid metamaterial that possesses both a negative mass density as well as an extremely tunable stiffness by properly utilizing both the mechanical and electric elements A multi-physical analytical model is first developed to investigate and reveal the tunable wave manipulation abilities in terms of both the effective negative mass density and/or bending stiffness of the hybrid metamaterial The programmed flexural wave manipulations, broadband negative refraction and waveguiding are then illustrated through three-dimensional (3D) multi-physical numerical simulations in hybrid metamaterial plates Our numerical results demonstrate that the flexural wave propagation can essentially be switched between “ON/OFF” states by connecting different shunting circuits

A hybrid elastic metamaterial with negative mass density and tunable bending stiffness

A general theory for bandgap estimation in locally resonant metastructures

Singular boundary method for wave propagation analysis in periodic structures

Wave propagation and attenuation in plates with periodic arrays of shunted piezo-patches

A periodic array of resistive inductive (RL) shunted piezoelectric (PZT) patches is applied to achieve tunable low-frequency locally resonant (LR) band gaps in a flexible isotropic beam. Each pair of surface-bonded PZT patches is linked to an independent RL circuit. All the circuits are the same and are tuned synchronously. A transfer matrix methodology is used to calculate the frequency range and attenuation properties of the LR band gap. Two main differences are found between the LR band gaps induced by shunting circuits and traditional oscillators. Antoniou's circuits are used to produce large ideal inductances necessary for low eigenfrequencies. The theoretical results are experimentally validated by measuring the harmonic response of the beam. Significant attenuation in the low-frequency LR band gap is observed.

https://iopscience.iop.org/article/10.1088/0964-1726/20/1/015026/pdf

Low-frequency locally resonant band gaps induced by arrays of resonant shunts with Antoniou’s circuit: experimental investigation on beams

Periodic arrays of piezoelectric patches connected by enhanced resonant shunting circuits are attached to a slender beam to control the propagation of vibration. Numerical models based on the transfer matrix methodology are constructed to predict the band structure, attenuation factors and the transmission of vibration in the proposed smart structure. The vibration attenuations of the proposed smart structure and that with the passive resonant shunting circuits are compared in order to verify the efficiency of the enhanced resonant shunting circuits. Vibration experiments are conducted in order to validate the theoretical predictions. The specimen with a combination of different types of resonant shunting circuits is also studied in order to gain wider attenuation frequency ranges.

https://iopscience.iop.org/article/10.1088/0964-1726/20/12/125019/pdf

Vibration attenuations induced by periodic arrays of piezoelectric patches connected by enhanced resonant shunting circuits

Periodic arrays of piezoelectric patches shunted by amplifier–resonator circuits are attached to a beam in order to gain large low-frequency attenuations in the propagation of flexural beam vibration. A numerical model based on the transfer matrix methodology and Bloch theory are built to predict the band gaps and attenuation factors as well as the transmission of vibration in the proposed smart metamaterials. Influences of circuital parameters on attenuation factors and the equivalent Young's modulus are studied. It is found that the central frequency of attenuations is lower than the resonant frequency because of the negative equivalent elastic modulus of piezoelectric patches at frequencies lower than the resonance. Finite element simulations and vibration experiments are conducted on a 10 mm-thick aluminium alloy beam with six pairs of piezoelectric patches glued on it. Based on theoretical calculations, three sets of circuital parameters are chosen to gain large vibration transmission attenuations around the lowest three modal peaks. Significant attenuation is found in the experimental results, which is predicted in theoretical calculations and finite element simulations. A superlattice metamaterial specimen with a combination of three different sets of circuital parameters is also studied in order to gain wide attenuation frequency ranges.

https://iopscience.iop.org/article/10.1088/0964-1726/25/1/015004/pdf

Large low-frequency vibration attenuation induced by arrays of piezoelectric patches shunted with amplifier–resonator feedback circuits

Periodic arrays of hybrid-shunted piezoelectric patches are used to control the band-gaps of phononic metamaterial beams. Passive resistive-inductive (RL) shunting circuits can produce a narrow resonant band-gap (RG), and active negative capacitive (NC) shunting circuits can broaden the Bragg band-gaps (BGs). In this article, active NC shunting circuits and passive resonant RL shunting circuits are connected to the same piezoelectric patches in parallel, which are usually called hybrid shunting circuits, to control the location and the extent of the band-gaps. A super-wide coupled band-gap is generated when the coupling between RG and the BG occurs. The attenuation constant of the infinite periodic structure is predicted by the transfer matrix method, which is compared with the vibration transmittance of a finite periodic structure calculated by the finite element method. Numerical results show that the hybrid-shunting circuits can make the band-gaps wider by appropriately selecting the inductances, negative capacitances, and resistances.

https://iopscience.iop.org/article/10.1088/1674-1056/24/3/036201/pdf

Shengbing Chen

Papers

Wave propagation and attenuation in plates with periodic arrays of shunted piezo-patches

Low-frequency locally resonant band gaps induced by arrays of resonant shunts with Antoniou’s circuit: experimental investigation on beams

Vibration attenuations induced by periodic arrays of piezoelectric patches connected by enhanced resonant shunting circuits

Large low-frequency vibration attenuation induced by arrays of piezoelectric patches shunted with amplifier–resonator feedback circuits

Flexural wave band-gaps in phononic metamaterial beam with hybrid shunting circuits