Flexoelectric Energy Harvesting of Circular Rings

2013 ◽  
Author(s):  
X. F. Zhang ◽  
S. D. Hu ◽  
H. S. Tzou
Keyword(s):  
Energy Harvesting ◽  
Output Power ◽  
Strain Gradient ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Excitation Frequency ◽  
Design Parameters ◽  
Equivalent Resistance ◽  
Flexoelectric Effect ◽  
Piezoelectric Energy

Flexoelectricity, the electromechanical coupling of the polarization response and strain gradient, occurs in solid crystalline dielectrics of any symmetry or asymmetric crystals. Different from the piezoelectric energy harvester, an energy harvester based on the direct flexoelectric effect is designed in this study. The energy harvester consists of an elastic ring and a flexoelectric patch laminated on its outer surface. Due to the direct flexoelectric effect, the electric energy induced by the strain gradient of the flexoelectric patch is harvested to power the electric device when the ring is subjected to mechanical excitations. Electromechanical coupling equation of the flexoelectric energy harvesting system in close-loop circuit condition is derived. In this study, dynamic response, output power across the external resistor and energy harvesting results are evaluated when the ring is excited by a harmonic point loading. The output power is a function of the external excitation frequency, the external equivalent resistance, the flexoelectric patch’s thickness and other design parameters. Case studies of those parameters for the flexoelectric energy harvester are presented to optimize the output power. Results show that the optimal excitation frequency is equal to the natural frequency for each mode, and the optimal equivalent resistance is dependent of the equivalent capacitance of the flexoelectric patch and the excitation frequency. Since the output power of the flexoelectric energy harvester is similar to that of the piezoelectric energy harvester, comparison of the two harvesters is also discussed. With all the optimal conditions discussed, it can supply a design principle in the engineering applications.

scholarly journals Modeling and Experiment of a V-Shaped Piezoelectric Energy Harvester

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Yue Zhao ◽  
Yi Qin ◽  
Lei Guo ◽  
Baoping Tang
Keyword(s):  
Energy Harvesting ◽  
Frequency Band ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Structural Parameters ◽  
Ambient Vibration ◽  
Piezoelectric Bimorph ◽  
Actual Structure ◽  
Piezoelectric Energy ◽  
Operation Frequency

Vibration-based energy harvesting technology is the most promising method to solve the problems of self-powered wireless sensor nodes, but most of the vibration-based energy harvesters have a rather narrow operation bandwidth and the operation frequency band is not convenient to adjust when the ambient frequency changes. Since the ambient vibration may be broadband and changeable, a novel V-shaped vibration energy harvester based on the conventional piezoelectric bimorph cantilevered structure is proposed, which successfully improves the energy harvesting efficiency and provides a way to adjust the operation frequency band of the energy harvester conveniently. The electromechanical coupling equations are established by using Euler-Bernoulli equation and piezoelectric equation, and then the coupled circuit equation is derived based on the series connected piezoelectric cantilevers and Kirchhoff's laws. With the above equations, the output performances of V-shaped structure under different structural parameters and load resistances are simulated and discussed. Finally, by changing the angle θ between two piezoelectric bimorph beams and the load resistance, various comprehensive experiments are carried out to test the performance of this V-shaped energy harvester under the same excitation. The experimental results show that the V-shaped energy harvester can not only improve the frequency response characteristic and the output performance of the electrical energy, but also conveniently tune the operation bandwidth; thus it has great application potential in actual structure health monitoring under variable working condition.

Theoretical and experimental studies of a piezoelectric ring energy harvester

2019 ◽  
Vol 30 (7) ◽  
pp. 998-1009 ◽  
Author(s):  
XF Zhang ◽  
HS Tzou
Keyword(s):  
Energy Harvesting ◽  
Power Output ◽  
Output Voltage ◽  
Laboratory Experiments ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Experimental Studies ◽  
Design Parameters ◽  
Resistive Load ◽  
Practical Applications

Based on the electromechanical coupling of piezoelectricity, a piezoelectric ring energy harvester is designed and tested in this study, such that the harvester can be used to power electric devices in the closed-circuit condition. Output energies across the external resistive load are evaluated when the ring energy harvester is subjected to harmonic excitations, and various design parameters are discussed to maximize the power output. In order to validate the theoretical energy harvesting results, laboratory experiments are conducted. Comparing experiment results with theoretical ones, the errors between them are under 10% for the output voltage. Laboratory experiments demonstrate that the ring energy harvester is workable in practical applications.

scholarly journals Piezoelectric Performance of a Symmetrical Ring-Shaped Piezoelectric Energy Harvester Using PZT-5H under a Temperature Gradient

Micromachines ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 640
Author(s):  
Nannan Zhou ◽  
Rongqi Li ◽  
Hongrui Ao ◽  
Chuanbing Zhang ◽  
Hongyuan Jiang
Keyword(s):  
Growth Rate ◽  
Output Power ◽  
Output Voltage ◽  
Electromechanical Coupling ◽  
Energy Harvester ◽  
Rapid Development ◽  
Coupling Model ◽  
Output Performance ◽  
Piezoelectric Energy ◽  
Changing Trend

With the rapid development of microelectronics technology, low-power electronic sensors have been widely applied in many fields, such as Internet of Things, aerospace, and so on. In this paper, a symmetrical ring-shaped piezoelectric energy harvester (SR-PEH) is designed to provide energy for the sensor to detect the ambient temperature. The finite element method is used by utilizing software COMSOL 5.4, and the electromechanical coupling model of the piezoelectric cantilever is established. The output performance equations are proposed; the microelectromechanical system (MEMS) integration process of the SR-PEH, circuit, and sensor is stated; and the changing trend of the output power density is explained from an energy perspective. In the logarithmic coordinate system, the results indicate that the output voltage and output power are approximately linear with the temperature when the resistance is constant. In addition, the growth rate of the output voltage and output power decreases with an increase of resistance under the condition of constant temperature. In addition, with an increase of temperature, the growth rate of the output power is faster than that of the output voltage. Furthermore, resistance has a more dramatic effect on the output voltage, whereas temperature has a more significant effect on the output power. More importantly, the comparison with the conventional cantilever-shaped piezoelectric energy harvester (CC-PEH) shows that the SR-PEH can improve the output performance and broaden the frequency band.

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.

Theoretical modeling and analysis of a 2-degree-of-freedom hybrid piezoelectric–electromagnetic vibration energy harvester with a driven beam

2018 ◽  
Vol 29 (11) ◽  
pp. 2465-2476 ◽  
Author(s):  
Dan Zhao ◽  
Shaogang Liu ◽  
Qingtao Xu ◽  
Wenyi Sun ◽  
Tao Wang ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Output Power ◽  
Energy Harvester ◽  
Degree Of Freedom ◽  
Energy Output ◽  
Vibration Energy ◽  
Vibration Energy Harvester ◽  
Piezoelectric Energy ◽  
Electromagnetic Vibration ◽  
Operating Bandwidth

In the article, a novel 2-degree-of-freedom hybrid piecewise-linear piezoelectric–electromagnetic vibration energy harvester is presented to achieve better energy harvesting efficiency. The harvester consists of a primary piezoelectric energy harvesting device to which an electromagnetic mechanism is coupled to improve the integral energy output, and a driven beam is mounted to broaden the operating bandwidth by inducing nonlinearity. Considering the piezoelectric–electromagnetic coupling characteristics and the nonlinear factors, dynamic equations of the system are established. Expressions of the output power are deduced though averaging method. Characteristic parameters are analyzed theoretically, including the piezoelectric parameters, electromagnetic parameters, and the piecewise-linearity. Frequency sweep excitation test is conducted on the setup at an excitation acceleration of 0.3 g and results demonstrate that two resonant regions are obtained with the peak output power of 5.4 and 6.49 mW, respectively, and the operating bandwidth is increased by 8 Hz. Moreover, though adjusting the stiffness of the driven beam k3 and the gap between the primary beam and the driven beam d, the performance of the harvester can be further optimized.

scholarly journals Analytical Electromechanical Modeling of Nanoscale Flexoelectric Energy Harvesting

2019 ◽  
Vol 9 (11) ◽  
pp. 2273 ◽  
Author(s):  
Yaxuan Su ◽  
Xiaohui Lin ◽  
Rui Huang ◽  
Zhidong Zhou
Keyword(s):  
Energy Harvesting ◽  
Power Density ◽  
Output Power ◽  
Electromechanical Coupling ◽  
Scale Effects ◽  
Dielectric Materials ◽  
Small Scale ◽  
Mechanical Excitation ◽  
Piezoelectric Energy ◽  
Intrinsic Length

With the attention focused on harvesting energy from the ambient environment for nanoscale electronic devices, electromechanical coupling effects in materials have been studied for many potential applications. Flexoelectricity can be observed in all dielectric materials, coupling the strain gradients and polarization, and may lead to strong size-dependent effects at the nanoscale. This paper investigates the flexoelectric energy harvesting under the harmonic mechanical excitation, based on a model similar to the classical Euler–Bernoulli beam theory. The electric Gibbs free energy and the generalized Hamilton’s variational principle for a flexoelectric body are used to derive the coupled governing equations for flexoelectric beams. The closed-form electromechanical expressions are obtained for the steady-state response to the harmonic mechanical excitation in the flexoelectric cantilever beams. The results show that the voltage output, power density, and mechanical vibration response exhibit significant scale effects at the nanoscale. Especially, the output power density for energy harvesting has an optimal value at an intrinsic length scale. This intrinsic length is proportional to the material flexoelectric coefficient. Moreover, it is found that the optimal load resistance for peak power density depends on the beam thickness at the small scale with a critical thickness. Our research indicates that flexoelectric energy harvesting could be a valid alternative to piezoelectric energy harvesting at micro- or nanoscales.

Piezoelectric Energy Harvester Adjusted by Light-Induced Actuator

2016 ◽  
Vol 851 ◽  
pp. 526-531
Author(s):  
Ya Na Mao ◽  
Guo Jin Chen
Keyword(s):  
Shape Memory ◽  
Output Power ◽  
Energy Harvester ◽  
Shape Memory Polymer ◽  
Excitation Frequency ◽  
Variable Stiffness ◽  
Laminated Beam ◽  
Piezoelectric Energy ◽  
Piezoelectric Layers ◽  
Smart Actuator

Shape-memory polymer has two different effects, i.e. shape memory effect and variable stiffness effect. Significant Young’s modulus changes when an external stimulus is applied. Light-induced shape memory polymer exhibits great potential in application of actuators because of its reconfigurableness, adaptiveness and non-contact control. In this paper, a smart actuator based on light-induced shape memory polymer is applied to improve the output power of piezoelectric energy harvester. This energy harvester is a laminated beam structure which includes five layers. Two piezoelectric layers are attached on the upper and lower surfaces of substrate layer. Then two light-induced actuators are bonded on the piezoelectric layers to adjust the frequency of this laminated beam via variable stiffness effect. Output power of the energy harvester could be promoted after the light-induced actuation since the natural frequency approaching the excitation frequency.

scholarly journals Orthogonal Piezoelectric Energy Harvester for Low Frequency Applications: Modeling and Experimental Validation

2019 ◽  
Vol 8 (4) ◽  
pp. 6268-6274
Keyword(s):  
Piezoelectric Material ◽  
Output Power ◽  
Experimental Validation ◽  
Energy Harvester ◽  
Excitation Frequency ◽  
Low Frequency ◽  
Galvanized Steel ◽  
Rotational Inertia ◽  
Acceptable Error ◽  
Piezoelectric Energy

The use of piezoelectric energy harvesters in low frequency applications is a classic problem due to the high elastic modulus of currently available piezoelectric materials. Furthermore, the output power is proportional to the third power of the excitation frequency. Higher excitation amplitudes or an increase in the piezoelectric material can produce a high output power. However, this is not feasible for weak environmental vibration, and using more piezoelectric material would incur a higher cost so this is not an attractive option. This article proposes an L-shaped piezoelectric energy harvester that amplifies the excitation amplitude with the aid of an extension arm. The effects of bending and rotational inertia are considered when modelling the open-circuit voltage that can be generated by the harvester. Experimental validation is carried out using zinc, aluminium and galvanized steel extension arms. The prediction model provides a good estimation of the results with acceptable error percentages for linear elastic extension arms. It is found that the proposed harvester geometry generates more output voltage for all lengths of extension arm, and the optimum lengths are different for each material. The use of a zinc extension arm generated 290 µW at 49 Hz, which is 55% greater than the power generated by a harvester without an extension arm that had a power density of 1.41 µW/mm3 .

scholarly journals Enhancing Wind Energy Harvesting Using Passive Turbulence Control Devices

2019 ◽  
Vol 9 (5) ◽  
pp. 998 ◽  
Author(s):  
Junlei Wang ◽  
Guoping Li ◽  
Shengxi Zhou ◽  
Grzegorz Litak
Keyword(s):  
Wind Speed ◽  
Energy Harvesting ◽  
Output Power ◽  
Electromechanical Coupling ◽  
Load Resistance ◽  
Turbulence Control ◽  
Critical Wind Speed ◽  
Piezoelectric Energy ◽  
Optimal Load ◽  
Passive Turbulence Control

Aiming to predict the performance of galloping piezoelectric energy harvesters, a theoretical model is established and verified by experiments. The relative error between the model and experimental results is 5.3%. In addition, the present model is used to study the AC output characteristics of the piezoelectric energy harvesting system under passive turbulence control (PTC), and the influence of load resistance on the critical wind speed, displacement, and output power under both strong and weak coupling are analyzed from the perspective of electromechanical coupling strength, respectively. The results show that the critical wind speed initially increases and then decreases with increasing load resistance. For weak and critical coupling cases, the output power firstly increases and then decreases with the increase of the load resistance, and reaches the maximum value at the optimal load. For the weak, critical, and strong coupling cases, the critical optimal load is 1.1 MΩ, 1.1 MΩ, and 3.0 MΩ, respectively. Overall, the response mechanism of the presented harvester is revealed.

Uncertainty Analysis of Energy Harvesting Systems

2014 ◽  
Author(s):  
Reza Madankan ◽  
M. Amin Karami ◽  
Puneet Singla
Keyword(s):  
Energy Harvesting ◽  
Power Output ◽  
Energy Harvester ◽  
Vibrational Energy ◽  
Excitation Frequency ◽  
Excitation Amplitude ◽  
Design Parameters ◽  
Unscented Transformation ◽  
Energy Harvesters ◽  
Harvesting Systems

This paper presents the relation between uncertainty in the excitation and parameters of vibrational energy harvesting systems and their power output. Nonlinear vibrational energy harvesters are very sensitive to the frequency of the base excitation. If the excitation frequency does not match with the resonance frequency of the energy harvester, the power output significantly deteriorates. The mismatch can be due to the inherent changes of the ambient oscillations. The fabrication errors or gradual changes of material properties also result in the mismatch. This paper quantitatively shows the probability density function for the power as a function of the probability densities of the excitation frequency, excitation amplitude, initial deflection of the energy harvester, and design parameters. Recently developed the conjugated unscented transformation methodology is used in conjunction with the principle of maximum entropy to compute the probability distribution for the base response and power. The computed nonlinear density functions are validated against Monte Carlo simulations.

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