Application Of Phononic Crystals Research Articles

2D phononic-crystal Luneburg lens for all-angle underwater sound localization

Phononic crystals are well known for acoustic wave manipulation which may have potential application in an underwater acoustic detection system. In this work, we design and simulate a two-dimensional Luneburg lens based on gradient-index (GRIN) phononic crystal that is composed of PLA-Air inclusion, and a novel application of GRIN phononic crystals is proposed to sound localization. The Luneburg lens has a broadband working range, from 1500 Hz to 7500 Hz, for acoustic wave focusing with sensitive directivity and signal-to-noise improvement. By searching maximum wave intensity’s position of the focusing beam, the propagating direction of an unknown sound wave can be directly recognized covering 360°. Besides, we redesign the conventional square-lattice Luneburg lenses using annular lattices for better performance. The annular-lattice Luneburg lens overcomes the weakness of configuration defect due to the square lattice. The numerical results show that the redesign Luneburg lenses have high accuracy for distance measurement from 5 m to 35 m through the triangulation location. In a word, this work tries to explore a novel application of phononic crystals in underwater acoustic positioning and navigation technology.

Space–time wave localization in electromechanical metamaterial beams with programmable defects

A relevant feature for various applications of phononic crystals and metamaterials is the wave localization and guiding using defects introduced into a periodic array. In this context, we present a flexible localization of elastic waves in piezoelectric metamaterial beams with space–time-modulated defects. The vibration energy, originally confined in a point defect, is gradually manipulated in space and time as the inductances of the shunt circuits of subsequent unit cells are properly controlled, perfectly inducing energy localization at the final defect position. This wave localization by programmable defects is also applied to a two-dimensional triangular lattice composed by piezoelectric metamaterial beams, which illustrates the potential and versatility of the proposed strategy in more complex systems. The space–time modulation of point defects presented in this work opens new possibilities for programmable wave localization, and hence, manipulation of vibration energy or information using smart metamaterials, with applications that may involve guiding, sensing, monitoring and energy harvesting.

Acoustic-elastic metamaterials and phononic crystals for energy harvesting: a review

Metamaterials and phononic crystals (PCs) with artificially designed periodic microstructures have attracted increasing research interests due to their unique properties that cannot be easily realized in natural materials. In recent years, the applications of metamaterials and PCs have been extended into the field of energy harvesting. A direct integration design strategy can yield a multifunctional system to suppress undesired vibrations/noise and convert them into electrical energy for providing power supply to widely distributed micro-electromechanical systems. Moreover, the defect state mode of metamaterials/PCs can localize the energy with an amplification effect, which has a great potential for improving energy harvesting efficiency. In addition, through tailoring the refractive index profile of metamaterials/PCs, the wave focusing phenomenon can be realized to boost the energy harvesting efficiency over a wide frequency range. This paper presents a comprehensive overview of the state-of-the-art advances in this direction over the past decade. According to the design strategies and working mechanisms, the existing studies in the literature on this topic are outlined and classified into three different categories. The advantages and disadvantages of various configurations are compared. The potential solutions to the existing drawbacks are discussed. An outlook on future prospects in this area is provided.

Band Gap and Vibration Reduction Properties of Damped Rail with Two-Dimensional Honeycomb Phononic Crystals

The prevention of environmental vibration pollution induced by train operation is one of the inevitable problems in the construction of urban rail transit. With the advantage of flexible adjustment, phononic crystals (PCs) have a broad application prospect in suppressing elastic wave propagation of rail transit. In this paper, a damped rail with two-dimensional honeycomb PCs was proposed, and its band structure was analysed with FEM. Then, a parametric study was used to investigate the influences of design parameters of the honeycomb PCs on its band gap property. Furthermore, with a 3D half-track model, the vibration reduction property of the damped rail with honeycomb PCs was discussed. The results show that the damped rail with honeycomb PCs has an absolute band gap in the frequency range of 877.3–1501.7 Hz, which includes the pinned-pinned resonance frequency of the rail internally. Reducing the filling fraction and elastic modulus of the matrix can obtain an absolute band gap in a lower frequency range but also bring a narrower bandwidth. The decrease of scatterer density leads to higher boundary frequencies of the absolute band gap and descends the bandwidth. In order to obtain an absolute band gap which can suppress the pinned-pinned resonance of the rail and keep a wider bandwidth, the filling fraction is suitable to be about 0.5, and the elastic modulus of the matrix is proposed to be not more than 0.6 MPa. Metals with heavy density can be used as the scatterer to obtain a better vibration reduction effect. It is hoped that the research results can provide a reference for the application of PCs in track vibration reduction.

Characterization of ceramic phononic crystals prepared with additive manufacturing: Ultrasonic technique and finite element analysis

Phononic crystals (PCs) are composed of two or more elastic materials arranged periodically. One of the important characteristics of PCs is the band gap. Band gap is the frequency range within which elastic waves are not allowed to transmit. With the band gap, applications of PCs include filters for body waves and surface acoustic waves. In the recent years, the additive manufacturing technique has been widely employed to fabricate objects with complicated geometries like PCs. In this study, samples of ceramic PCs were fabricated with the additive manufacturing technique. In addition to that Finite Element Analysis (FEA) was employed to predict the band gaps of PCs fabricated with the traditional and the additive manufacturing technique. Experimental measurements with pulsed ultrasound technique together with fast Fourier Transform (FFT) were employed to measure the band gaps. In general, measurement results agree well with the FEA results. The outcomes of this study suggest a new PCs fabrication method based on the additive manufacturing technique.

Thermal properties of one-dimensional piezoelectric phononic crystal

By using the transfer matrix method, we theoretically studied the propagation of a longitudinal acoustic wave in a one-dimensional phononic crystal (PnC) that contains a piezoelectric material as a defect layer. A pass band can be generated and controlled in the middle of the band gap. The pass band position is tuned by applying an external electric field. The position of the pass band inside the band gap is tuned by the changing of temperature. We introduce a comparison between temperature effects on two piezoelectric materials, PZT-5H and 0.7 PMN-0.3PT inside a PnC structure. Moreover, the pass band is shifted towards high or low frequencies by temperature decrement or increment, respectively. The simulated results provide a valuable guidance for PnC applications such as acoustic switch and temperature sensor.

Wave propagation in viscoelastic phononic crystal rods with internal resonators

In the present work, the wave propagation in a viscoelastic phononic crystal rod with internal periodic dissipative resonators is investigated. The Kelvin-Voigt model is utilized to describe the viscoelastic behavior of host materials. The Bloch theorem is adopted to analyze the band structure of the rod. The effect of the free oscillation frequency of the resonators on the band structure is firstly studied. It is found that by tailoring the dynamic characteristics of the resonators, the coupling of the Bragg scattering (BS) and local resonance (LR) mechanisms can be harnessed to effectively widen the band gaps and enhance the wave attenuation. Then, the effects of the viscosity of the host materials and the damping of the resonators on the band structure, especially the two nearly coalescent band gaps (the first Bragg and LR ones), are investigated respectively. Furthermore, the combined effect of the two dissipative sources is also discussed. The present work is expected to be helpful to the design and applications of phononic crystals and metamaterials.

Investigation of quasi-one-dimensional finite phononic crystal with conical section

In this paper, we studied the propagation of elastic longitudinal waves in quasi-one-dimensional (1D) finite phononic crystal with conical section, and derived expressions of frequency-response functions. It is found that, contrary to the 1D phononic crystal with a constant section, the value of attenuation inside the band gaps decreases quickly when cross-sectional area increases, and the initial frequency also decreases, but the cut-off frequency increases, thus the width of the band gap increases. The effects of lattice constant and the filling fraction on the band gap are also analysed, and the change trends of the initial frequency and cut-off frequency are consistent with those of constant section. It is shown that the results using this method are in good agreement with the results analysed by the finite element software, ANSYS. We hope that the results will be helpful in practical applications of phononic crystals.

Diffraction phenomena associated with a composite plate containing an interior periodically corrugated interface

The interest in the study and applications of phononic crystals has naturally lead to the investigation of other novel periodic structures. The present work examines the case of a plate constructed of two solid layers of differing elastic properties separated by a periodically corrugated interface. It is shown how the dispersion curves are influenced by the internal corrugated interface and how they evolve as a function of the magnitude of this corrugation. Internal diffraction effects alter the dispersion properties and thus have an important effect on the composite when it is used as an acoustic filter. These effects are also important for the transmission and reflection of sound when the composite is used as a panel or when it is the intention to generate Lamb waves to investigate the composite plate nondestructively.

Design and characterization of stop-band filters using PZT layer on silicon substrate phononic crystals

Phononic crystals are periodic structures exhibiting absolute band gaps i.e. frequency bands in which the propagation of elastic waves is forbidden in all directions. Filtering is then a possible application of phononic crystals. Recently, the existence of absolute band gaps has also been theoretically demonstrated for guided elastic waves in a piezoelectric plate on a substrate [J. Vasseur et al, J. Appl. Phys, 101, 114904 (2007)], which is a geometry of interest for possible co-integration on silicon chip. The 2D phononic crystal was constituted by a square arrangement of cylindrical holes in a PZT layer deposited on a silicon substrate. In this communication, the realization of a stop-band filter constituted by a periodically patterned PZT layer, polarized along thickness, on silicon substrate and interdigitated electrodes (IDE) for emission/reception of guided elastic waves, is investigated. The filter characteristics are theoretically evaluated by using finite element simulations: dispersion curves of patterned PZT layer are computed for various pattern geometries to obtain the absolute band gap. Complete structure is then modeled, with appropriate IDE to propagate a guided mode in the piezoelectric layer. Finally, filtering capability of the structure is evaluated. Work supported by STMicroelectronics (Nano2008 program of French ministry of industry).

Study on the vibration band gap and vibration attenuation property of phononic crystals

Phononic crystals (PCs) are functional materials with periodic structures and elastic wave (vibration) band gaps, where propagation of vibrations with frequencies within band gaps is forbidden. PCs with finite periods can restrain the propagation of vibrations with frequencies in band gaps and thus has vibration attenuation property. Worldwide, many institutions and researchers are engaged in the research of PCs, however, studies on the vibration attenuation property of PCs are still limited. In this paper, we report our study of band gaps and vibration attenuation properties of 1) a simplified PC—periodic mass-spring structures, 2) longitudinal vibration of one-dimensional (1D-), 2D-, 3D-PCs, and 3) the flexural vibration of 1D-and 2D-PCs. These studies provide a foundation for the applications of PCs in vibration attenuation.

Increased Efficiency of Surface Wave Stimulation on the Inaccessible Side of a Thick Isotropic Plate with Superimposed Periodicity

Because of the growing number of applications of phononic crystals and other periodic structures, there is a renewed and growing interest in understanding the interaction of ultrasound with periodically corrugated surfaces. This paper presents a theoretical investigation of the transformation of ultrasound incident from the solid side onto a solid-liquid periodically corrugated interface. It is shown that it is possible to tailor the shape of a corrugated surface with given periodicity such that there is a significant amount of energy transformed into Scholte-Stoneley waves than if pure saw-tooth or sine-shaped surfaces were used. This permits the fabrication of periodic structures that can be patched on or engraved in body parts of a construction and enables efficient generation of Scholte-Stoneley waves. The study is performed for incident homogeneous plane waves as well as for bounded beams. Incident longitudinal waves are studied as well as incident shear waves.

Flexural vibration band gaps in thin plates with two-dimensional binary locally resonant structures

The complete flexural vibration band gaps are studied in the thin plates with two-dimensional binary locally resonant structures, i.e. the composite plate consisting of soft rubber cylindrical inclusions periodically placed in a host material. Numerical simulations show that the low-frequency gaps of flexural wave exist in the thin plates. The width of the first gap decreases monotonically as the matrix density increases. The frequency response of the finite periodic thin plates is simulated by the finite element method, which provides attenuations of over 20dB in the frequency range of the band gaps. The findings will be significant in the application of phononic crystals.

Doubly coupled vibration band gaps in periodic thin-walled open cross-section beams

This paper studies flexural-torsional doubly coupled vibration through periodic thin-walled open cross-section beams composed of two kinds of materials. Based on the doubly coupled vibration equation, plane wave expansion method for the thin-walled beams is provided. If the filling fraction keeps constant, the lattice is one of the factors that affect the normalized gap width. If the lattice and filling fraction keeps constant, the Young modulus contrast plays a fundamental role for the band gap width, but not density contrast. Finally, the frequency response of a finite periodic binary beam is simulated by finite element method, which provides an attenuation of about 40dB in the frequency range of the band gaps. The findings will be significant in the application of phononic crystals.