Elastic Metasurfaces for Full Wavefront Control and Low-Frequency Energy Harvesting

2021 ◽  
pp. 1-22
Author(s):  
Zhenkun Lin ◽  
Serife Tol
Keyword(s):  
Energy Harvesting ◽  
Acoustic Waves ◽  
Focal Point ◽  
Numerical Models ◽  
Low Frequency ◽  
Single Layer ◽  
Theoretical Models ◽  
Propagation Path ◽  
Phase Gradient ◽  
Wave Amplification

Abstract Controlling and manipulating elastic/acoustic waves via artificially structured metamaterials, phononic crystals, and metasurfaces have gained an increasing research interest in the last decades. Unlike others, a metasurface is a single layer in the host medium with an array of subwavelength-scaled patterns introducing an abrupt phase shift in the wave propagation path. In this study, an elastic metasurface composed of an array of slender beam resonators is proposed to control the elastic wavefront of low-frequency flexural waves. The phase gradient based on the Snell's law is achieved by tailoring the thickness of thin beam resonators connecting two elastic host media. Through analytical and numerical models, the phase-modulated metasurfaces are designed and verified to accomplish three dynamic wave functions, namely, deflection, non-paraxial propagation, and focusing. An oblique incident wave is also demonstrated to show the versatility of the proposed design for focusing of wave energy incident from multiple directions. Experimentally measured focusing metasurface has nearly three times wave amplification at the designed focal point which validates the design and theoretical models. Furthermore, the focusing metasurface is exploited for low frequency energy harvesting and the piezoelectric harvester is improved by almost nine times in terms of the harvested power output as compared to the baseline harvester on the pure plate without metasurface.

scholarly journals Numerical and Theoretical Models for NFRCM-Strengthened Masonry

2019 ◽  
Vol 817 ◽  
pp. 44-49
Author(s):  
Claudia Brito de Carvalho Bello ◽  
Daniele Baraldi ◽  
Giosuè Boscato ◽  
Antonella Cecchi ◽  
Olimpia Mazzarella ◽  
...  
Keyword(s):  
Parametric Analysis ◽  
Numerical Models ◽  
Pushover Analysis ◽  
Single Layer ◽  
Theoretical Models ◽  
Layer Model ◽  
Cementitious Matrix ◽  
Reinforced Masonry ◽  
Homogenized Model ◽  
Fabric Reinforced Cementitious Matrix

The shear behavior of masonry strengthened with natural fabric-reinforced cementitious matrix (NFRCM-strengthened masonry) is investigated through two different numerical models: a multi-layer model considering masonry and reinforcement as different materials and a multi-step homogenized model, where reinforced masonry is considered as a whole. The approaches are compared by performing nonlinear numerical pushover analysis with an increasing shear action applied to the panels. The parametric analysis shows the capacity and limits of both continuous diffused models – defined as a multi-or a single layer - to represent reinforced masonry in-plane behavior.

scholarly journals Theory and application of reverberated direct and indirect noise

2017 ◽  
Vol 819 ◽  
pp. 435-464 ◽  
Author(s):  
E. O. Rolland ◽  
F. De Domenico ◽  
S. Hochgreb
Keyword(s):  
Acoustic Waves ◽  
Transfer Functions ◽  
Low Frequency ◽  
Theoretical Models ◽  
Orifice Plate ◽  
Electric Heater ◽  
Flow Restriction ◽  
Temperature Disturbance ◽  
First Time ◽  
Entropy Perturbation

The generation of a temperature disturbance in a flow is accompanied by the production of acoustic waves (direct noise) and of an entropy perturbation. If this entropy perturbation is accelerated or decelerated (as is the case through a nozzle or flow restriction), additional acoustic waves are generated (indirect noise). Several studies have demonstrated this mechanism in controlled conditions by using entropy wave generators, in which entropy waves are generated and convected through a nozzle, leading to direct and indirect noise. An analytical analysis of the direct and indirect noise produced by the generation and acceleration of entropy waves in a reflective environment is presented. The effect of reverberation (repeated acoustic reflections) on low-frequency perturbations (characteristic of entropy wave generators) is determined analytically. These results are then implemented in a set of limit cases, showing the limit behaviours of such systems. The analytical model is applied to the case of the Cambridge entropy wave generator experiment, in which entropy waves are generated by an electric heater and accelerated through a subsonic orifice plate. Due to the clear time separation of direct and indirect noise in the experimental results, direct and indirect noise transfer functions can be extracted from the experimental data for the first time and compared directly with existing theoretical models. The backward-propagating indirect noise generated at an orifice plate is shown to be significantly higher than predicted by existing theoretical models for isentropic nozzles.

scholarly journals Piezoelectric Energy Harvesting from Suspension Structures with Piezoelectric Layers

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3755 ◽  
Author(s):  
Min Wang ◽  
Yiming Xia ◽  
Huayan Pu ◽  
Yi Sun ◽  
Jiheng Ding ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Impedance Matching ◽  
Low Frequency ◽  
Single Layer ◽  
Leaf Spring ◽  
Piezoelectric Energy Harvesting ◽  
Piezoelectric Energy ◽  
Low Frequency Vibration ◽  
Piezoelectric Layers ◽  
Series Of Experiments

In this paper, we propose a generator for piezoelectric energy harvesting from suspension structures. This device consists of a leaf spring and eight pairs of piezoelectric layers attached to inner and outer surfaces. We present a special type of leaf spring, which can magnify the force from the workload to allow the piezoelectric layers to achieve larger deformation. The generator is to solve the problem of vibration energy reutilization in a low-frequency vibration system. To verify the efficiency of the proposed configuration, a series of experiments are operated. The results indicate that the resonance frequency (25.2 Hz) obtained from the sweep experiment is close to the simulation result (26.1 Hz). Impedance-matching experiments show that the sum of the output power attains 1.7 mW, and the maximum single layer reaches 0.6 mW with an impedance matching of 610 KΩ, and the instantaneous peak-peak power density is 3.82 mW/cm3. The capacitor-charging performance of the generator is also excellent under the series condition. For a 4.7 μF capacitor, the voltage is charged to 25 V in 30 s and limited at 32 V in 80 s. These results demonstrate the exploitable potential of piezoelectric energy harvesting from suspension structures.

Elastic Metasurfaces for Low-Frequency Flexural Wavefront Control

2020 ◽  
Author(s):  
Zhenkun Lin ◽  
Serife Tol
Keyword(s):  
Elastic Waves ◽  
Phase Modulation ◽  
Lamb Waves ◽  
Numerical Models ◽  
Low Frequency ◽  
Propagation Path ◽  
Wavefront Control ◽  
Thin Beam ◽  
Modulated Structure ◽  
Host Medium

Abstract Controlling elastic/acoustic wave-front via compact designs has attracted increasing research interest in past decades. The emerging of metasurface concept provides an unconventional and attractive approach in this filed. A metasurface generally consists of a single array of subwavelength-scaled patterns in the host medium, introducing an abrupt phase shift in the wave propagation path. In this paper, we explored an elastic metasurface concept to control the propagation of low-frequency flexural Lamb waves. The phase modulation based on the Snell’s law was achieved by tailoring the thickness of thin beam resonators connecting two elastic host medium. Depending on the design of the phase-modulated structure (a.k.a. metasurface), elastic waves could be steered or focused which was verified through analytical and numerical models.

scholarly journals Single-layer phase gradient mmWave metasurface for incident angle independent focusing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wonwoo Lee ◽  
Semin Jo ◽  
Kanghyeok Lee ◽  
Hong Soo Park ◽  
Junhyuk Yang ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
High Performance ◽  
Phase Distribution ◽  
Focal Point ◽  
Incident Angle ◽  
Rapid Development ◽  
Single Layer ◽  
Phase Gradient ◽  
Wave Focusing ◽  
Practical Applications

AbstractMetasurfaces allow the rapid development of compact and flat electromagnetic devices owing to their capability in manipulating the wavefront of electromagnetic waves. Particularly, with respect to the metasurface lenses, wide operational bandwidth and wide incident angle behavior are critically required for practical applications. Herein, a single-layer phase gradient metasurface lens is presented to achieve millimeter-wave focusing at a focal point of 13 mm regardless of the incident angle. The proposed metasurface lens is fabricated by constructing subwavelength-thick (< λ/10) phase elements composed of two metallic layers separated by a single dielectric substrate that exhibits low-Q resonance properties and a wide phase modulation range with satisfactory transmissivity. By controlling the spatial phase distribution, the proposed metasurface lens successfully realises effective wavefront manipulation properties and high-performance electromagnetic-wave-focusing characteristics over a wide operating frequency range from 35 to 40 GHz with incident angle independency up to 30°.

scholarly journals Independently Tunable Multipurpose Absorber with Single Layer of Metal-Graphene Metamaterials

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 284
Author(s):  
Chen Han ◽  
Renbin Zhong ◽  
Zekun Liang ◽  
Long Yang ◽  
Zheng Fang ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Fermi Level ◽  
Potential Application ◽  
Single Layer ◽  
Wide Band ◽  
Metamaterial Absorber ◽  
Unit Cell ◽  
Perfect Absorption ◽  
Solar Energy Harvesting ◽  
Band Absorption

This paper reports an independently tunable graphene-based metamaterial absorber (GMA) designed by etching two cascaded resonators with dissimilar sizes in the unit cell. Two perfect absorption peaks were obtained at 6.94 and 10.68 μm with simple single-layer metal-graphene metamaterials; the peaks show absorption values higher than 99%. The mechanism of absorption was analyzed theoretically. The independent tunability of the metamaterial absorber (MA) was realized by varying the Fermi level of graphene under a set of resonators. Furthermore, multi-band and wide-band absorption were observed by the proposed structure upon increasing the number of resonators and resizing them in the unit cell. The obtained results demonstrate the multipurpose performance of this type of absorber and indicate its potential application in diverse applications, such as solar energy harvesting and thermal absorbing.

scholarly journals Experiment Investigation of Bistable Vibration Energy Harvesting with Random Wave Environment

2021 ◽  
Vol 11 (9) ◽  
pp. 3868
Author(s):  
Qiong Wu ◽  
Hairui Zhang ◽  
Jie Lian ◽  
Wei Zhao ◽  
Shijie Zhou ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Energy Harvesting ◽  
Cantilever Beam ◽  
Large Scale ◽  
Low Frequency ◽  
Vibration Energy ◽  
Random Wave ◽  
Periodic Signal ◽  
Vibration Energy Harvesting ◽  
Motion Activity

The energy harvested from the renewable energy has been attracting a great potential as a source of electricity for many years; however, several challenges still exist limiting output performance, such as the package and low frequency of the wave. Here, this paper proposed a bistable vibration system for harvesting low-frequency renewable energy, the bistable vibration model consisting of an inverted cantilever beam with a mass block at the tip in a random wave environment and also develop a vibration energy harvesting system with a piezoelectric element attached to the surface of a cantilever beam. The experiment was carried out by simulating the random wave environment using the experimental equipment. The experiment result showed a mass block’s response vibration was indeed changed from a single stable vibration to a bistable oscillation when a random wave signal and a periodic signal were co-excited. It was shown that stochastic resonance phenomena can be activated reliably using the proposed bistable motion system, and, correspondingly, large-scale bistable responses can be generated to realize effective amplitude enlargement after input signals are received. Furthermore, as an important design factor, the influence of periodic excitation signals on the large-scale bistable motion activity was carefully discussed, and a solid foundation was laid for further practical energy harvesting applications.

scholarly journals Visualization of Surface Acoustic Waves in Thin Liquid Films

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
R. W. Rambach ◽  
J. Taiber ◽  
C. M. L. Scheck ◽  
C. Meyer ◽  
J. Reboud ◽  
...  
Keyword(s):  
Liquid Film ◽  
Acoustic Waves ◽  
Low Cost ◽  
Thin Liquid Film ◽  
Surface Acoustic Waves ◽  
Liquid Films ◽  
Theoretical Description ◽  
Propagation Path ◽  
Microfluidic Channels ◽  
Potential Applications

Abstract We demonstrate that the propagation path of a surface acoustic wave (SAW), excited with an interdigitated transducer (IDT), can be visualized using a thin liquid film dispensed onto a lithium niobate (LiNbO3) substrate. The practical advantages of this visualization method are its rapid and simple implementation, with many potential applications including in characterising acoustic pumping within microfluidic channels. It also enables low-cost characterisation of IDT designs thereby allowing the determination of anisotropy and orientation of the piezoelectric substrate without the requirement for sophisticated and expensive equipment. Here, we show that the optical visibility of the sound path critically depends on the physical properties of the liquid film and identify heptane and methanol as most contrast rich solvents for visualization of SAW. We also provide a detailed theoretical description of this effect.

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