scholarly journals Enhancing the Electromechanical Coupling in Soft Energy Harvesters by Using Graded Dielectric Elastomers

Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1187
Author(s):  
Lingling Chen ◽  
Shengyou Yang
Keyword(s):  
Electromechanical Coupling ◽  
Failure Modes ◽  
Energy Harvester ◽  
Large Deformations ◽  
Maximum Energy ◽  
Outer Radius ◽  
Dielectric Films ◽  
Dielectric Elastomers ◽  
Energy Harvesters ◽  
New Energy

Soft dielectric elastomers can quickly achieve large deformations when they are subjected to electromechanical loads. They are widely used to fabricate a number of soft functional devices. However, the functions of soft devices are limited to the failure modes of soft dielectric elastomers. In this paper, we use graded dielectric elastomers to produce a soft energy harvester with a strong ability of energy harvesting. Compared to the conventional energy harvester with homogeneous dielectric films, our new energy harvester is made of graded elastomers and can increase both the specific energy from 2.70 J/g to 2.93 J/g and the maximum energy from 6.3 J/g to 8.6 J/g by just using a stiffer outer radius. By optimizing the material parameters in graded dielectric films, the soft energy harvester can reach better performance, and our results can provide guidance for designing powerful energy harvesters.

Enhanced frequency synchronization for concurrent aeroelastic and base vibratory energy harvesting using a softening nonlinear galloping energy harvester

2021 ◽  
pp. 1045389X2110263
Author(s):  
Shun Chen ◽  
David Eager ◽  
Liya Zhao
Keyword(s):  
Energy Harvesting ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Poor Performance ◽  
Effective Bandwidth ◽  
Frequency Synchronization ◽  
Periodic Oscillations ◽  
Energy Harvesters ◽  
Paper Form ◽  
Excited Oscillation

This paper proposes a softening nonlinear aeroelastic galloping energy harvester for enhanced energy harvesting from concurrent wind flow and base vibration. Traditional linear aeroelastic energy harvesters have poor performance with quasi-periodic oscillations when the base vibration frequency deviates from the aeroelastic frequency. The softening nonlinearity in the proposed harvester alters the self-excited galloping frequency and simultaneously extends the large-amplitude base-excited oscillation to a wider frequency range, achieving frequency synchronization over a remarkably broadened bandwidth with periodic oscillations for efficient energy conversion from dual sources. A fully coupled aero-electro-mechanical model is built and validated with measurements on a devised prototype. At a wind speed of 5.5 m/s and base acceleration of 0.1 g, the proposed harvester improves the performance by widening the effective bandwidth by 300% compared to the linear counterpart without sacrificing the voltage level. The influences of nonlinearity configuration, excitation magnitude, and electromechanical coupling strength on the mechanical and electrical behavior are examined. The results of this paper form a baseline for future efficiency enhancement of energy harvesting from concurrent wind and base vibration utilizing monostable stiffness nonlinearities.

Equivalent impedance and power analysis of monostable piezoelectric energy harvesters

2020 ◽  
Vol 31 (14) ◽  
pp. 1697-1715
Author(s):  
Chunbo Lan ◽  
Yabin Liao ◽  
Guobiao Hu ◽  
Lihua Tang
Keyword(s):  
Equivalent Circuit ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Performance Enhancement ◽  
Damping Ratio ◽  
Power Performance ◽  
Closed Form Solutions ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Power Limit

Nonlinearity has been successfully introduced into piezoelectric energy harvesting for power performance enhancement and bandwidth enlargement. While a great deal of emphasis has been placed by researchers on the structural design and broadband effect, this article is motivated to investigate the maximum power of a representative type of nonlinear piezoelectric energy harvesters, that is, monostable piezoelectric energy harvester. An equivalent circuit is proposed to analytically study and explain system behaviors. The effect of nonlinearity is modeled as a nonlinear stiffness element mechanically and a nonlinear capacitive element electrically. Facilitated by the equivalent circuit, closed-form solutions of power limit and critical electromechanical coupling, that is, minimum coupling to reach the power limit, of monostable piezoelectric energy harvesters are obtained, which are used for a clear explanation of the system behavior. Several important conclusions have been drawn from the analytical analysis and validated by numerical simulations. First, given the same level of external excitation, the monostable piezoelectric energy harvester and its linear counterpart are subjected to the same power limit. Second, while the critical coupling of linear piezoelectric energy harvesters depends on the mechanical damping ratio only, it also depends on the vibration excitation and magnetic field for monostable piezoelectric energy harvesters, which can be used to adjust the power performance of the system.

scholarly journals Design and Analysis of a Magnetically Coupled Multi-Frequency Hybrid Energy Harvester

Sensors ◽  
2019 ◽  
Vol 19 (14) ◽  
pp. 3203 ◽  
Author(s):  
Zhenlong Xu ◽  
Hong Yang ◽  
Hao Zhang ◽  
Huawei Ci ◽  
Maoying Zhou ◽  
...  
Keyword(s):  
Output Power ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Hybrid Energy ◽  
Energy Harvesters ◽  
Peak Output Power ◽  
Piezoelectric Energy ◽  
Operating Bandwidth ◽  
Frequency Sweep Test ◽  
Hybrid Energy Harvesting

The approach to improve the output power of piezoelectric energy harvester is one of the current research hotspots. In the case where some sources have two or more discrete vibration frequencies, this paper proposed three types of magnetically coupled multi-frequency hybrid energy harvesters (MHEHs) to capture vibration energy composed of two discrete frequencies. Electromechanical coupling models were established to analyze the magnetic forces, and to evaluate the power generation characteristics, which were verified by the experimental test. The optimal structure was selected through the comparison. With 2 m/s2 excitation acceleration, the optimal peak output power was 2.96 mW at 23.6 Hz and 4.76 mW at 32.8 Hz, respectively. The superiority of hybrid energy harvesting mechanism was demonstrated. The influences of initial center-to-center distances between two magnets and length of cantilever beam on output power were also studied. At last, the frequency sweep test was conducted. Both theoretical and experimental analyses indicated that the proposed MHEH produced more electric power over a larger operating bandwidth.

Tapered galloping energy harvester for power enhancement and vibration reduction

2019 ◽  
Vol 30 (18-19) ◽  
pp. 2853-2869
Author(s):  
Lingzhi Wang ◽  
Ting Tan ◽  
Zhimiao Yan ◽  
Zhitao Yan
Keyword(s):  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Constant Width ◽  
Uniform Design ◽  
Theoretic Model ◽  
Modal Shape ◽  
Energy Harvesters ◽  
Power Enhancement ◽  
Uniform Cross Section ◽  
Piezoelectric Strain

The cantilever beam was commonly designed with uniform cross-section for the galloping energy harvesters. To improve its performance, two tapered galloping energy harvesters are proposed in this work. In the first tapered design, the beam’s thickness is linearly changed with constant width. In the second tapered design, both the beam’s thickness and width are linearly varied. A generalized fluid–structure–electricity coupled distributed-parameter model is established by the Hamilton principle and Gauss law for the tapered galloping energy harvesters. By means of the properties of the Bessel function and the modal analysis method, the exact analytical modal shape of the tapered beam is derived. The effects of the tapered ratio on the beam mass, bending stiffness, electrical field, electromechanical coupling, and piezoelectric capacitance are accounted by the proposed theoretic model. Finite element analyses and wind tunnel experiments are performed, and the results show good agreement with the proposed beam modal shape, corresponding natural frequency and harvested power. The tapered ratio is tuned to realize the even distribution of the piezoelectric strain along the beam length. Compared with the uniform design, the tapered galloping energy harvester exhibits merits on up to [Formula: see text] power enhancement and [Formula: see text] vibration deduction.

scholarly journals Method for controlling vibration by exploiting piecewise-linear nonlinearity in energy harvesters

2020 ◽  
Vol 476 (2233) ◽  
pp. 20190491
Author(s):  
Meng-Hsuan Tien ◽  
Kiran D’Souza
Keyword(s):  
Energy Harvester ◽  
Control Method ◽  
Piecewise Linear ◽  
Response Prediction ◽  
Ocean Waves ◽  
Human Motion ◽  
Automatic Frequency ◽  
Energy Harvesters ◽  
New Energy ◽  
Potential Applications

Vibration energy is becoming a significant alternative solution for energy generation. Recently, a great deal of research has been conducted on how to harvest energy from vibration sources ranging from ocean waves to human motion to microsystems. In this paper, a theoretical model of a piecewise-linear (PWL) nonlinear vibration harvester that has potential applications in variety of fields is proposed and numerically investigated. This new technique enables automatic frequency tunability in the energy harvester by controlling the gap size in the PWL oscillator so that it is able to adapt to changes in excitations. To optimize the performance of the proposed system, a control method combining the response prediction, signal measurement and gap adjustment mechanism is proposed in this paper. This new energy harvester not only overcomes the limitation of traditional linear energy harvesters that can only provide the maximum power generation efficiency over a narrow frequency range but also improves the performance of current nonlinear energy harvesters that are not as efficient as linear energy harvesters at resonance. The proposed system is demonstrated in several case studies to illustrate its effectiveness for a number of different excitations.

A Flexoelectric Double-Curvature Nonlinear Shell Energy Harvester

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
H. S. Tzou ◽  
X. F. Zhang
Keyword(s):  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Current Model ◽  
Circular Ring ◽  
Resistive Load ◽  
Energy Harvesters ◽  
Flexoelectric Effect ◽  
Double Curvature ◽  
Power Outputs ◽  
Shell Energy

Flexoelectricity possesses two gradient-dependent electromechanical coupling effects: the direct flexoelectric effect and the converse flexoelectric effect. The former can be used for sensing and energy generation; the latter can be used for ultraprecision actuation and control applications. Due to the direct flexoelectricity and large deformations, theoretical fundamentals of a generic nonlinear distributed flexoelectric double-curvature shell energy harvester are proposed and evaluated in this study. The generic flexoelectric shell energy harvester is made of an elastic double-curvature shell laminated with flexoelectric patches and the shell experiences large oscillations, such that the von Karman geometric nonlinearity occurs. Flexoelectric output voltages and energies across a resistive load are evaluated using the current model in the closed-circuit condition when the shell is subjected to harmonic excitations and its steady-state voltage and power outputs are also calculated. The generic flexoelectric shell energy harvesting theory can be simplified to shell (e.g., cylindrical, conical, spherical, paraboloidal, etc.) and nonshell (beam, plate, ring, arch, etc.) distributed harvesters and the simplification procedures are demonstrated in three cases, i.e., a cylindrical shell, a circular ring and a beam harvester. Other shell and nonshell flexoelectric energy harvesters with standard geometries can also be defined using their distinct two Lamé parameters and two curvature radii.

scholarly journals Design of a Compact and Highly Efficient Energy Harvester System Suitable for Battery-Less Low Cost On-Board Unit Applications

Electronics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 3
Author(s):  
Giovanni Collodi ◽  
Stefano Maddio ◽  
Giuseppe Pelosi
Keyword(s):  
Power Supply ◽  
Performance Optimization ◽  
Energy Harvester ◽  
Low Cost ◽  
Maximum Energy ◽  
Matching Network ◽  
Energy Harvesters ◽  
Vehicle Identification ◽  
Source Impedance ◽  
Toll Collection

This study addresses the general problem regarding the power supply in specific on-board unit (OBUs) solutions. In detail, this paper refers to a subset of the so-called electronic toll collection (ETC) applications such as assets control and vehicle identification, where simplicity, low costs, and maximum compactness represent the most important features. In this context, the next generation of OBUs, developed specifically with reference to such applications, will involve energy harvester-based battery-less techniques. Previous studies have mainly concentrated on performance optimization by achieving maximum energy transmission to the OBUs. This study discusses a technique suitable for both maximizing performance and minimizing the dimensions of transponder energy harvesters suitable for assets control and vehicle identification operating at 5.8 GHz. The technique assumes that an optimal source impedance exists that maximizes the energy transfer to the transponder, thus enabling its power supply in a battery-less configuration. We discuss a solution based on a compact patch antenna designed to exhibit this optimal source impedance to the RF-to-DC rectifier. This approach avoids the use of a lossy matching network. For the sake of comparison, the same function is compared with an equivalent development, which includes the interstage matching network between the antenna and the RF-to-DC rectifier. We introduce experimental results demonstrating that the ultracompact energy harvester optimized at −5 dBm of impinging power is capable of increasing both the charge current and energy efficiency from 340 to 450 μA and from 37% to 47%, respectively.

scholarly journals Role of Electromechanical Coupling, Locomotion Type and Damping on the Effectiveness of Fish-Like Robot Energy Harvesters

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 693
Author(s):  
Ryan Salazar ◽  
Ryan Quintana ◽  
Abdessattar Abdelkefi
Keyword(s):  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Spinal Column ◽  
Electromechanical Model ◽  
Energy Harvesters ◽  
Relative Strain ◽  
Convergence Study ◽  
Locomotion Type ◽  
Influential Parameters

In this work, an investigation into the influence of prescribed motion on a body caudal fin aquatic unmanned vehicle (AUV) energy harvester is carried out. The undulatory–oscillation locomotion inspired by fishes actuates a composite beam representative of a spinal column with a piezoelectric patch. Two patch configurations—one at the head and tail—are considered for the AUV energy harvester, with a length that would not activate a harmonic in the system. An electromechanical model which accounts for the strain of the prescribed motion and the induced relative strain is developed. Discretizing the relative strain using Galerkin’s method requires a convergence study in which the impacts of the prescribed motion, dependent on the undulation and envelope of the motion, are investigated. The combination of prescribed motion and structural terms leads to a coupling that requires multiple investigations. The removal of the undulation of the system produces a more consistent response. The performances of the two different patch configurations undergoing different prescribed motions are studied in terms of coupled damping and frequency effects. An uncoupled Gauss law-based model is adopted to compare the performance of our approach and that of the coupled electromechanical model harvester. It is demonstrated that there is a complex interaction of the phases of the prescribed and relative motions of the structure which can lead to the development or destruction of the response of the total motion or voltage for the system. The results show that the structural damping and type of locomotion are the most influential parameters on the validity of the uncoupled approach. It is also found that the optimal resistances for the coupled and uncoupled representations are the same for the two motions and patch configurations considered.

Flexoelectric energy harvesters based on Timoshenko laminated beam theory

2017 ◽  
Vol 28 (15) ◽  
pp. 2064-2073 ◽  
Author(s):  
Xu Liang ◽  
Runzhi Zhang ◽  
Shuling Hu ◽  
Shengping Shen
Keyword(s):  
Resonance Frequency ◽  
Energy Conversion ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Mechanical Energy ◽  
Mechanical Vibration ◽  
Beam Theory ◽  
Electrical Energy ◽  
Laminated Beam ◽  
Energy Harvesters

Different from piezoelectricity which is restricted to certain materials, flexoelectricity is a universal electromechanical coupling in all dielectrics. In this work, mechanical energy harvester models were developed based on Timoshenko laminated beam theory, in which the flexoelectric and piezoelectric mechanisms were discussed. For a three-layered energy harvester in parallel configuration, the mechanical vibration energy can be converted into electrical energy due to flexoelectricity, and for the three-layered energy harvester in series configuration, the energy conversion is enhanced by the flexoelectricity. Resonance frequency shifts were observed in the calculations due to flexoelectricity and external circuit resistance. It is found that the electromechanical coupling displayed from the electrical responses versus resonance frequency and resistance. The energy conversion for the three-layered energy harvester system was found to be increased with the decrease in the laminated beam thickness. The energy conversion calculated for different numbers of layers also indicates that laminated energy harvester systems excel single-layered energy harvesters. This work therefore might help in designing flexoelectricity-based energy harvesters.

Analysis of delamination of unimorph cantilever piezoelectric energy harvesters

2018 ◽  
Vol 29 (9) ◽  
pp. 1875-1883 ◽  
Author(s):  
Shan Zeng ◽  
Chunwei Zhang ◽  
Kaifa Wang ◽  
Baolin Wang ◽  
Li Sun
Keyword(s):  
Power Output ◽  
Failure Modes ◽  
Energy Harvester ◽  
Present Model ◽  
Load Resistance ◽  
Active Length ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Unimorph Cantilever ◽  
Power Outputs

Unimorph piezoelectric energy harvesters are typically a unimorph cantilever beam located on a vibrating host structure. Delamination is one of the major failure modes of such unimorph cantilevers and therefore is studied in this article. The delaminated cantilever unimorph is modeled with one through-width crack using four Euler beams connected at delamination edges. The governing equations, the corresponding boundary conditions, and the kinematic continuity conditions are derived based on the Hamiltonian principle. The solutions of the voltage and power output for the present model are derived. The influence of the position and the length of the delamination, frequency of input base excitation, and load resistance on the voltage and power output are discussed in detail. The results show that delamination in the unimorph of the energy harvester will impressively decrease the voltage and power outputs. Influences of the delamination located at the free end of the cantilever are more obvious. For a given active length of the delaminated cantilever energy harvester, it is useful to increase the overall length of the cantilever to obtain a higher voltage and power outputs.

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