A Piezoelectric Metamaterial With Bistable Circuit Shunts for Adaptive Non-Reciprocal Elastic Wave Transmission

2018 ◽  
Author(s):  
Yisheng Zheng ◽  
Zhen Wu ◽  
Xinong Zhang ◽  
K. W. Wang
Keyword(s):  
Elastic Wave ◽  
Wave Energy ◽  
Excitation Frequency ◽  
Forward Direction ◽  
Excitation Amplitude ◽  
Wave Transmission ◽  
Transmission Characteristics ◽  
Energy Transmission ◽  
Wave Propagation Direction ◽  
Stable Equilibria

In this paper, we present a piezoelectric metamaterial integrated with bistable circuits to realize adaptive non-reciprocal elastic wave transmission. Dynamics of the bistable circuit and the piezoelectric metamaterial are investigated numerically to analyze the wave transmission characteristics of the proposed system. Results reveal that when the excitation amplitude exceeds certain threshold, wave energy is able to propagate even with excitation frequency inside the local-resonance bandgap of the piezoelectric metamaterial. This bandgap transmission phenomenon is also known as supratransmission. It is shown that by introducing spatial asymmetry, the system could exhibit different supratransmission thresholds when it is actuated in opposite directions, and hence there exists an excitation range within which wave energy is only able to propagate in one direction. Furthermore, this excitation range to facilitate non-reciprocal energy transmission is adaptable by adjusting the stable equilibria of the bistable circuits, which can be conveniently tuned utilizing only DC voltage sources. Additionally, it is shown that by adjusting the stable equilibria, the wave propagation direction, analogous to the forward direction of an electrical diode, can be easily reversed. Lastly, in contrast to many nonlinearity enabled non-reciprocal systems, the proposed system is able to realize non-reciprocal elastic energy transmission with majority of the transmitted energy preserved at the original input frequency. Overall, these results illustrate a new means of utilizing nonlinear piezoelectric metamaterial to manipulate elastic wave transmission.

Nonreciprocal Wave Transmission in Metastable Modular Metastructures Utilizing Asymmetric Dual-Threshold Snap-Through

2019 ◽  
Author(s):  
Xiang Liu ◽  
Guoping Cai ◽  
K. W. Wang
Keyword(s):  
Potential Energy ◽  
Excitation Frequency ◽  
Excitation Amplitude ◽  
Wave Transmission ◽  
Dimensional Structure ◽  
Two Dimensional ◽  
One Dimensional ◽  
Threshold Phenomenon ◽  
Energy Equilibrium ◽  
Nonreciprocal Transmission

Abstract In this research, the nonreciprocal wave transmission features in one-dimensional and two-dimensional metastable modular metastructures are studied. Unlike previous work, in which the nonreciprocal transmission in metastable metastructures is realized by utilizing the supratransmission phenomenon when the excitation frequency is inside the linearized bandgap, a new approach is explored to achieve nonreciprocal wave transmission exploiting metastability and asymmetric dual-threshold snap-through. It is found that because of the asymmetry of potential energy wells of the equilibria, there will be two excitation amplitude thresholds for a metastable component when it is initially at the high-potential-energy equilibrium with excitation frequency within the passband. When the excitation amplitude increases and exceeds the first threshold, the metastable component will snap to the low-potential-energy equilibrium and maintain intrawell motion around this stable point, which will cause a significant decrease of the wave transmission. And when the excitation amplitude exceeds the second threshold, the metastable component will start to perform interwell motion, and now the wave transmission will increase suddenly. By using this “dual-threshold” phenomenon, nonreciprocal wave transmission in a one-dimensional structure is realized by connecting a metastable chain with a linear periodic part. Because of the wave attenuation effect of the linear part of the system, the excitation amplitude thresholds on different sides of the one-dimensional structure will be discrepant. Therefore, nonreciprocal wave transmission can be developed when the excitation amplitude is within certain ranges. It is interesting to note that the direction of nonreciprocal wave transmission can be changed by setting the excitation amplitude to different values. By changing the configuration of the metastable chain, the operation frequency and excitation amplitude ranges of the nonreciprocal transmission can be tuned. For a two-dimensional metastable metastructure, nonreciprocal wave transmission can be realized by adjusting the parameters of some metastable modules in the metastructure in the manner that the potential energy and energy thresholds of the adjusted modules and the unadjusted modules are different, but the passbands of the adjusted modules and the unadjusted modules will overlap in some frequency regions. Numerical studies provide clear insight of the proposed nonreciprocal wave transmission approach.

scholarly journals Analysis of Tire Acoustic Cavity Resonance Energy Transmission Characteristics in Wheels Based on Power Flow Method

2021 ◽  
Vol 11 (9) ◽  
pp. 3979
Author(s):  
Wei Zhao ◽  
Yuting Liu ◽  
Xiandong Liu ◽  
Yingchun Shan ◽  
Xiaojun Hu
Keyword(s):  
Power Flow ◽  
Resonance Energy ◽  
Cavity Resonance ◽  
Propagation Path ◽  
Material Structure ◽  
Transmission Characteristics ◽  
Energy Transmission ◽  
Flow Method ◽  
Acoustic Cavity ◽  
Power Flow Method

As a kind of low-frequency vehicle interior noise, tire acoustic cavity resonance noise plays an important role, since the other noise (e.g., engine noise, wind noise and friction noise) has been largely suppressed. For the suspension system, wheels stand first in the propagation path of this energy. Therefore, it is of great significance to study the influence of wheel design on the transmission characteristics of this vibration energy. However, currently the related research has not received enough attention. In this paper, two sizes of aluminum alloy wheel finite element models are constructed, and their modal characteristics are analyzed and verified by experimental tests simultaneously. A mathematically fitting sound pressure load model arising from the tire acoustic cavity resonance acting on the rim is first put forward. Then, the power flow method is applied to investigate the resonance energy distribution and transmission characteristics in the wheels. The structure intensity distribution and energy transmission efficiency can be described and analyzed clearly. Furthermore, the effects of material structure damping and the wheel spoke number on the energy transmission are also discussed.

Guided wave‐based cable damage detection using wave energy transmission and reflection

2021 ◽  
Author(s):  
Zhi‐Feng Tang ◽  
Xiao‐Dong Sui ◽  
Yuan‐Feng Duan ◽  
Peng‐fei Zhang ◽  
Chung Bang Yun
Keyword(s):  
Damage Detection ◽  
Wave Energy ◽  
Guided Wave ◽  
Energy Transmission ◽  
Cable Damage ◽  
Transmission And Reflection

scholarly journals A Phononic Crystal with Differently Configured Double Defects for Broadband Elastic Wave Energy Localization and Harvesting

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 643
Author(s):  
Soo-Ho Jo ◽  
Byeng D. Youn
Keyword(s):  
Elastic Wave ◽  
Wave Energy ◽  
Phononic Crystal ◽  
Square Lattice ◽  
Energy Localization ◽  
Piezoelectric Patch ◽  
Single Defect ◽  
Piezoelectric Energy ◽  
Piezoelectric Effects ◽  
Elastic Wave Energy

Several previous studies have been dedicated to incorporating double defect modes of a phononic crystal (PnC) into piezoelectric energy harvesting (PEH) systems to broaden the bandwidth. However, these prior studies are limited to examining an identical configuration of the double defects. Therefore, this paper aims to propose a new design concept for PnCs that examines differently configured double defects for broadband elastic wave energy localization and harvesting. For example, a square-pillar-type unit cell is considered and a defect is considered to be a structure where one piezoelectric patch is bonded to a host square lattice in the absence of a pillar. When the double defects introduced in a PnC are sufficiently distant from each other to implement decoupling behaviors, each defect oscillates like a single independent defect. Here, by differentiating the geometric dimensions of two piezoelectric patches, the defects’ dissimilar equivalent inertia and stiffness contribute to individually manipulating defect bands that correspond to each defect. Hence, with adequately designed piezoelectric patches that consider both the piezoelectric effects on shift patterns of defect bands and the characteristics for the output electric power obtained from a single-defect case, we can successfully localize and harvest the elastic wave energy transferred in broadband frequencies.

Effects of Acoustic Excitation on a Swirling Diffusion Flame

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Michael E. Loretero ◽  
Rong F. Huang
Keyword(s):  
Flow Field ◽  
Bluff Body ◽  
Excitation Frequency ◽  
Excitation Amplitude ◽  
Mie Scattering ◽  
Flame Length ◽  
Laser Doppler Velocimeter ◽  
Scattering Method ◽  
Acoustic Excitation ◽  
Characteristic Modes

A swirling double concentric jet is commonly used for nonpremixed gas burner application for safety reasons and to improve the combustion performance. Fuel is generally spurted at the central jet while the annular coflowing air is swirled. They are normally separated by a blockage disk where the bluff-body effects further enhance the recirculation of hot gas at the reaction zone. This paper aims to experimentally investigate the behavior of flame and flow in a double concentric jet combustor when the fuel supply is acoustically driven. Laser-light sheet assisted Mie scattering method has been used to visualize the flow, while the flame lengths were measured by a conventional photography technique. The fluctuating velocity at the jet exit was measured by a two-component laser Doppler velocimeter. Flammability and stability at first fuel tube resonant frequency are reported and discussed. The evolution of flame profile with excitation level is presented and discussed, together with the reduction in flame length. The flame in the unforced reacting axisymmetric wake is classified into three characteristic modes, which are weak swirling flame, lifted flame, and transitional reattached flame. These terms reflect their primary features of flame appearances, and when the acoustic excitation is applied, the flame behaviors change with the excitation frequency and amplitude. Four additional characteristic modes are identified; e.g., at low excitation amplitudes, wrinkling flame with a blue annular film is observed because the excitation induces vortices in the central fuel jet and hence gives rise to the wrinkling of flame. The central jet vortices become larger with the increase in excitation amplitude and thus lead to a wider and shorter flame. If the excitation amplitude is increased above a certain value, the central jet vortices change the rotation direction and pacing with the annular jet vortices. These changes in the flow field induce large turbulent intensity and mixing and therefore make the flame looks blue and short. Further increase in the excitation amplitude would lift the flame because the flow field would be dramatically modified.

Modeling and Experimental Validations of a Piezoelectric Energy Harvester Under Combined Galloping and Base Excitations

2014 ◽  
Author(s):  
Amin Bibo ◽  
Abdessattar Abdelkefi ◽  
Mohammed F. Daqaq
Keyword(s):  
Bluff Body ◽  
Energy Harvester ◽  
Constitutive Relations ◽  
Excitation Frequency ◽  
Primary Resonance ◽  
Beam Theory ◽  
Excitation Amplitude ◽  
The Body ◽  
Base Excitation ◽  
Piezoelectric Energy

This paper develops an experimentally validated model of a piezoelectric energy harvester under combined aeroelastic-galloping and base excitations. To that end, an energy harvester consisting of a thin piezoelectric cantilever beam subjected to vibratory base excitation is considered. To permit galloping excitation, a bluff body is rigidly attached at the free end such that a net aerodynamic lift is generated as the incoming airflow separates on both sides of the body giving rise to limit cycle oscillations when the flow velocity exceeds a critical value. A nonlinear electromechanical distributed-parameter model of the harvester under the combined excitation is derived using the energy approach and by adopting the nonlinear Euler-Bernoulli beam theory, linear constitutive relations for the piezoelectric transduction, and the quasi-steady assumption for the aerodynamic loading. The partial differential equations of the system are discretized and a reduced-order-model is obtained. The mathematical model is validated by conducting a series of experiments with different loading conditions represented by wind speed, base excitation amplitude, and excitation frequency around the primary resonance.

Two Groups of Chaotic Vibrations in a Single-Degree-of-Freedom Maglev System

1997 ◽  
Author(s):  
Zhixiang Xu ◽  
Hideyuki Tamura
Keyword(s):  
Magnetic Levitation ◽  
Excitation Frequency ◽  
Power Spectra ◽  
Period Doubling ◽  
Excitation Amplitude ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Moving Base ◽  
Period Doubling Bifurcations

Abstract In this paper, a single-degree-of-freedom magnetic levitation dynamic system, whose spring is composed of a magnetic repulsive force, is numerically analyzed. The numerical results indicate that a body levitated by magnetic force shows many kinds of vibrations upon adjusting the system parameters (viz., damping, excitation amplitude and excitation frequency) when the system is excited by the harmonically moving base. For a suitable combination of parameters, an aperiodic vibration occurs after a sequence of period-doubling bifurcations. Typical aperiodic vibrations that occurred after period-doubling bifurcations from several initial states are identified as chaotic vibration and classified into two groups by examining their power spectra, Poincare maps, fractal dimension analyses, etc.

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