Tapered Two-Layer Broadband Vibration Energy Harvesters

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Xingyu Xiong ◽  
S. Olutunde Oyadiji
Keyword(s):  
Power Density ◽  
Power Output ◽  
Electromechanical Coupling ◽  
Design Strategy ◽  
Dominant Mode ◽  
Vibration Energy ◽  
Electromechanical Coupling Coefficient ◽  
Mass Ratio ◽  
Energy Harvesters ◽  
Resonance Frequencies

Two-layer piezoelectric vibration energy harvesters using convergent and divergent tapered structures have been developed for broadband power output. The harvesters consist of a base cantilevered beam, which is attached to an upper beam by a spacer to develop a two-layer configuration. Two masses are attached to each layer to tune the resonance frequencies of each harvester and one of these masses also serves as the spacer. By varying the positions of the masses, the convergent and divergent tapered harvesters can generate close resonance frequencies and considerable power output in the first two modes. A broadband harvester design strategy is introduced based on a modal approach, which determines the modal performance using mass ratio and modal electromechanical coupling coefficient (EMCC). The required modal parameters are derived using the finite element method. Mass ratio represents the influence of the modal mechanical behavior on the power density directly. Since the dominant mode causes the remaining modes to have smaller mass ratios, smaller EMCC, and poor performance, the design strategy involves the selection of the harvester configurations with close resonances and favorable values of mass ratio initially, and deriving the EMCC and power density of those selected configurations.

Optimized Mechanical Performance of Cantilevered Vibration Energy Harvesters Using a Modal Approach

2014 ◽  
Author(s):  
X. Xiong ◽  
S. O. Oyadiji
Keyword(s):  
Electromechanical Coupling ◽  
Mechanical Performance ◽  
Vibration Energy ◽  
Electromechanical Coupling Coefficient ◽  
Mass Ratio ◽  
Modal Approach ◽  
Energy Harvesters ◽  
Cantilevered Beam ◽  
Full Analysis ◽  
Cantilevered Beams

In order to improve the performance of cantilevered vibration energy harvesters, current methods normally vary their geometric dimensions and derive the maximum power outputs by running a full analysis. This paper attempts to optimize the structural performance of cantilevered vibration energy harvesters using a modal approach without carrying out full analysis. The effects of varying geometrical dimensions on the modal mechanical performance are analysed, which includes the analysis on rectangular cantilevered beams with and without extra mass, the convergent and divergent tapered cantilevered beams. The modal approach uses mass ratio and the modal electromechanical coupling coefficient to determine the electrical and mechanical modal performance of vibration energy harvesters. In particular, mass ratio depends on the modal participation factor, and it represents the influence of modal mechanical behaviour on the power density directly. The required modal parameters are derived using the finite element method and a distributed parameter electromechanical model is also used for comparison. The cantilevered beam designs using the modal approach can be used with different sizes with the power ranging from microwatts to milliwatts.

scholarly journals Combined piezoelectric and flexoelectric effects in resonant dynamics of nanocantilevers

2018 ◽  
Vol 29 (20) ◽  
pp. 3949-3959 ◽  
Author(s):  
Adriane G Moura ◽  
Alper Erturk
Keyword(s):  
Barium Titanate ◽  
Frequency Response ◽  
Coupling Coefficient ◽  
Electromechanical Coupling ◽  
Analytical Framework ◽  
Electromechanical Coupling Coefficient ◽  
Sensors And Actuators ◽  
Energy Harvesters ◽  
Size Dependent ◽  
Resonant Dynamics

We establish and analyze an analytical framework by accounting for both the piezoelectric and flexoelectric effects in bimorph cantilevers. The focus is placed on the development of governing electroelastodynamic piezoelectric–flexoelectric equations for the problems of resonant energy harvesting, sensing, and actuation. The coupled governing equations are analyzed to obtain closed-form frequency response expressions via modal analysis. The combined piezoelectric–flexoelectric coupling coefficient expression is identified and its size dependence is explored. Specifically, a typical atomistic value of the flexoelectric constant for barium titanate is employed in the model simulations along with its piezoelectric constant from the existing literature. It is shown that the effective electromechanical coupling of a piezoelectric material, such as barium titanate, is significantly enhanced for thickness levels below 100 nm. The electromechanical coupling coefficient of a barium titanate bimorph cantilever increases from the bulk piezoelectric value of 0.065 to the combined piezoelectric–flexoelectric value exceeding 0.3 toward nanometer thickness level. Electromechanical frequency response functions for resonant power generation and dynamic actuation also capture the size-dependent enhancement of the electromechanical coupling. The analytical framework given here can be used for parameter identification and design of nanoscale cantilevers that can be used as energy harvesters, sensors, and actuators.

Experimental Investigation of a Piezoelectrically Actuated Rotating Parts Feeder

1997 ◽  
Author(s):  
S. H. Chang ◽  
T. W. Yang
Keyword(s):  
Mechanical System ◽  
Electromechanical Coupling ◽  
Laser Interferometer ◽  
Vertical Vibration ◽  
Electromechanical Coupling Coefficient ◽  
Automated Manufacturing ◽  
Electrical System ◽  
Resonance Frequencies ◽  
Displacement Sensitivity ◽  
Small Parts

Abstract The parts feeder provides both horizontal and vertical forces to transfer the small parts between stations in automated manufacturing processes. In this paper, the dynamic characteristics of a piezoelectrically actuated rotating parts feeder was evaluated. The model of the piezoelectric bimorph, the key component of the parts feeder, is formulated under DC and AC excitation. Experiments using laser interferometer, impedance analyzer and spectrum analyzer were conducted to measure displacement sensitivity, resonance frequencies and antiresonance frequencies of the electrical/mechanical system. Relations between driving frequencies and vibration amplitudes under various driving voltages were reported. From experimental results, the resonance frequencies of the mechanical system were identified at 176.6 Hz and 535 Hz. The first resonance and anti-resonance frequencies of the electrical system were found at 176.0 Hz and 177.5 Hz. The electromechanical coupling coefficient for piezoelectric actuator using Mason formula is 13%. Operating at the first resonance frequency, the parts feeder feeds at 17.66 mm/sec with a vertical vibration amplitude of 14.2 μ m.

scholarly journals Analysis on the Radial Vibration of Longitudinally Polarized Radial Composite Tubular Transducer

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4785
Author(s):  
Xiaoyu Wang ◽  
Shuyu Lin
Keyword(s):  
High Power ◽  
Coupling Coefficient ◽  
Piezoelectric Ceramic ◽  
Electromechanical Coupling ◽  
Electromechanical Coupling Coefficient ◽  
Radial Vibration ◽  
Resonance Frequencies ◽  
Second Mode ◽  
Radial Resonance ◽  
Effective Electromechanical Coupling Coefficient

The radial vibration of a radial composite tubular transducer with a large radiation range and power capacity is studied. The transducer is composed of a longitudinally polarized piezoelectric ceramic tube and a coaxial outer metal tube. Assuming that the longitudinal length is much larger than the radius, the electromechanical equivalent circuits of the radial vibration of a piezoelectric ceramic long tube and a metal long tube are derived and obtained for the first time following the plane strain theory. As per the condition of the continuous forces and displacements of two contact surfaces, the electromechanical equivalent circuit of the tubular transducer is obtained. The radial resonance/anti-resonance frequency equation and the expression of the effective electromechanical coupling coefficient are obtained. Then, the effects of the radial geometry dimension of the transducer on the vibration characteristics are analyzed. The theoretical resonance frequencies, anti-resonance frequencies, and the effective electromechanical coupling coefficients at the fundamental mode and the second mode are in good agreement with the finite element analysis (FEA) results. The study shows that when the overall size of the transducer is unchanged, as the proportion of piezoelectric ceramic increases, the radial resonance/anti-resonance frequency and the effective electromechanical coupling coefficient of the transducer at the fundamental mode and the second mode have certain characteristics. The radial composite tubular transducer is expected to be used in high-power ultrasonic wastewater treatment, ultrasonic degradation, and underwater acoustics, as well as other high-power ultrasonic fields.

Finite Element Analysis and Experimental Studies on the Thickness Resonance of Piezocomposite Transducers

1996 ◽  
Vol 18 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Wenkang Qi ◽  
Wenwu Cao
Keyword(s):  
Finite Element ◽  
Resonance Frequency ◽  
Electromechanical Coupling ◽  
Effective Medium Theory ◽  
Experimental Studies ◽  
Effective Medium ◽  
Electromechanical Coupling Coefficient ◽  
Element Analysis ◽  
Medium Theory ◽  
Resonance Frequencies

Finite element method (FEA) has been used to calculate the thickness resonance frequency and electromechanical coupling coefficient kt for 2–2 piezocomposite transducers. The results are compared with that of the effective medium theory and also verified by experiments. It is shown that the predicted resonance frequencies from the effective medium theory and the unit cell modeling using FEA deviate from the experimental observations for composite systems with a ceramic aspect ratio (width/length) more than 0.4. For such systems, full size FEA modeling is required which can provide accurate predictions of the resonance frequency and thickness coupling constant kt.

Variation of Material Properties of Piezoelectric Ceramics due to Electric Loading Evaluated by Resonance Frequency

2007 ◽  
Vol 345-346 ◽  
pp. 1521-1524 ◽  
Author(s):  
Mamoru Mizuno ◽  
Nozomi Odagiri ◽  
Mitsuhiro Okayasu
Keyword(s):  
Electric Field ◽  
Resonance Frequency ◽  
Lead Zirconate Titanate ◽  
Material Properties ◽  
Electromechanical Coupling ◽  
Domain Switching ◽  
Piezoelectric Ceramics ◽  
Lead Zirconate ◽  
Electromechanical Coupling Coefficient ◽  
Resonance Frequencies

In the present paper, lead zirconate titanate (PZT) and lead titanate (PT) piezoelectric ceramics were subjected to both high electric field (which is higher than the coercive electric field) with low frequency and low electric field with high frequency (which is the resonance frequency). After applying certain electric field systematically, resonance and anti-resonance frequencies and an electrostatic capacity were measured by means of an impedance analyzer, and an electromechanical coupling coefficient, a dielectric constant, an elastic coefficient and a piezoelectric constant were evaluated from the frequencies and capacity measured. Then variation of the material properties in process of time was investigated experimentally, and the dependence of the variation of the properties due to mainly domain switching on conditions of applied electric field was elucidated.

scholarly journals The Effect of Axial Displacement of Magnets in Piezoelectric Energy Harvester

2018 ◽  
Vol 7 (3.7) ◽  
pp. 95
Author(s):  
Li Wah Thong ◽  
Yu Jing Bong ◽  
Swee Leong Kok ◽  
Roszaidi Ramlan
Keyword(s):  
Frequency Spectrum ◽  
Power Output ◽  
Energy Harvester ◽  
Vibrational Energy ◽  
Vibration Energy ◽  
Vibration Energy Harvester ◽  
Energy Harvesters ◽  
Piezoelectric Energy ◽  
Operational Frequency ◽  
And Performance

The utilization of vibration energy harvesters as a substitute to batteries in wireless sensors has shown prominent interest in the literature. Various approaches have been adapted in the energy harvesters to competently harvest vibrational energy over a wider spectrum of frequencies with optimize power output.   A typical bistable piezoelectric energy harvester, where the influence of magnetic field is induced into a linear piezoelectric cantilever, is designed and analyzed in this paper. The exploitations of the magnetic force specifically creates nonlinear response and bistability in the energy harvester that extends the operational frequency spectrum for optimize performance.  Further analysis on the effects of axial spacing displacement between two repulsive magnets of the harvester, in terms of x-axis (horizontal) and z-axis (vertical) on its natural resonant frequency and performance based on the frequency response curve are investigated for realizing optimal power output. Experimental results show that by selecting the optimal axial spacing displacement, the vibration energy harvester can be designed to produce maximized output power in an improved broadband of frequency spectrum.  

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