Performance of a Randomly-Excited Nonlinear Energy Harvester in Mono- and Bi-Stable Potentials: An Experimental Investigation

2012 ◽  
Author(s):  
Ravindra Masana ◽  
Mohammed F. Daqaq
Keyword(s):  
Axial Load ◽  
Energy Harvester ◽  
Performance Comparison ◽  
Resistive Load ◽  
Energy Characteristics ◽  
Energy Harvesters ◽  
Post Buckling ◽  
Compressive Axial Load ◽  
Oscillation Frequencies ◽  
Nonlinear Energy

This paper aims to experimentally investigate the influence of stiffness-type nonlinearities on the transduction of vibratory energy harvesters (VEHs) under random white and colored excitations. For the purpose of the study, an energy harvester consisting of a clamped-clamped piezoelectric beam bi-morph is considered. The shape of the harvester’s potential function is altered by applying a static compressive axial load at one end of the beam. The axial load permits the harvester to operate with different potential energy characteristics; namely, the mono-stable (pre-buckling) and bi-stable (post-buckling) configurations. The performance of the harvester in both configurations is investigated and compared by tuning the harvester’s oscillation frequencies around the static equilibria such that they have equal values in both scenarios. The harvester is then subjected to random base excitations of different levels, bandwidths, and center frequencies. The variance of the output voltage is measured across an arbitrary, purely resistive load and used for the purpose of performance comparison. Critical conclusions pertinent to the influence of the nonlinearity and relative performance in both configurations are presented and discussed.

Comparing the Performance of a Nonlinear Energy Harvester in Mono- and Bi-Stable Potentials

2011 ◽  
Author(s):  
Ravindra Masana ◽  
Mohammed F. Daqaq
Keyword(s):  
Oscillation Frequency ◽  
Energy Harvester ◽  
Performance Measure ◽  
Performance Comparison ◽  
Energy Harvesters ◽  
New Class ◽  
Wide Range ◽  
Post Buckling ◽  
Stable Equilibria ◽  
Nonlinear Energy

The quest to develop broadband vibratory energy harvesters (VEHs) has recently motivated researchers to explore introducing nonlinearities into the harvester’s design. Some research efforts have demonstrated that this new class of nonlinear harvesters can outperform their traditional linear (resonant) counterparts; some others however concluded that nonlinearities can diminish the harvester’s transduction. Through this effort, we compare the performance of a nonlinear VEH operating in mono- and bi-stable potentials. With that objective, we consider an axially-loaded clamped-clamped piezoelectric beam which functions as an energy harvester in the mono-stable (pre-buckling) and bistable (post-buckling) configurations. For the purpose of fair performance comparison, the oscillation frequency around the stable equilibria of the harvester is tuned to equal values in both configurations. The harvester is then subjected to harmonic base excitations of different magnitudes and a slowly-varying frequency which spans a wide range around the tuned oscillation frequency. The output voltage measured across an arbitrarily chosen electric load is used as a relative performance measure. Both numerical and experimental results demonstrate that the shape of the potential function plays an essential role in conjunction with the magnitude of the base excitation to determine whether the bi-stable harvester can outperform the mono-stable one and for what range of frequencies.

Design enhancement and non-dimensional analysis of magnetically-levitated nonlinear vibration energy harvesters

2017 ◽  
Vol 28 (19) ◽  
pp. 2810-2822 ◽  
Author(s):  
Abdullah Nammari ◽  
Hamzeh Bardaweel
Keyword(s):  
Energy Harvesting ◽  
Energy Harvester ◽  
Magnetic Levitation ◽  
Energy Harvesters ◽  
The Past ◽  
Magnetic Forces ◽  
Linear Version ◽  
Harvesting Techniques ◽  
Unique Potential ◽  
Nonlinear Energy

Over the past decade, there has been special interest in developing nonlinear energy harvesters capable of operating over a wideband frequency spectrum. Chief among the nonlinear energy harvesting techniques is magnetic levitation–based energy harvesting. Nonetheless, current nonlinear magnetic levitation–based energy harvesting approaches encapsulate design challenges. This work investigates some of the design issues and limitations faced by traditional magnetic levitation–based energy harvesters such as damping schemes and stiffness nonlinearities. Both experiment and model are used to quantify and evaluate damping regimes and stiffness nonlinearities present in magnetic levitation–based energy harvesters. Results show that dry friction, mostly ignored in magnetic levitation–based energy harvesting literature, contributes to the overall energy dissipation. Measured and modeled magnetic forces–displacement curves suggest that stiffness nonlinearities are weak over moderate distances. An enhanced design utilizing a combination of mechanical and magnetic springs is introduced to overcome some of these limitations. A non-dimensional model of the proposed design is developed and used to investigate the enhanced architecture. The unique potential energy profile suggests that the proposed nonlinear energy harvester outperforms the linear version by steepening the displacement response and shifting the resonance frequency, resulting in a larger bandwidth for which power can be harvested.

Increasing viability of nonlinear energy harvesters by adding an excited dynamic magnifier

2017 ◽  
Vol 29 (6) ◽  
pp. 1196-1205 ◽  
Author(s):  
Brian P Bernard ◽  
Brian P Mann
Keyword(s):  
Peak Power ◽  
Energy Harvester ◽  
Basin Of Attraction ◽  
Unit Mass ◽  
Energy Harvesters ◽  
The Past ◽  
Design Characteristics ◽  
The Cost ◽  
The Basin Of Attraction ◽  
Nonlinear Energy

Dynamic magnifiers and coupled harvester arrays are two strategies that have been developed over the past decade to improve the peak power and bandwidth of energy harvesters. However, both of these methods come with drawbacks. Dynamic magnifiers require retuning since they change the frequency of the peak response and some designs result in decreased power per unit mass. Coupled harvester arrays can increase the overall bandwidth, but also include central valleys between the peaks and a significant increase in the cost. This article describes an excited dynamic magnifier which borrows design characteristics from both traditional dynamic magnifiers and harvester arrays in order to overcome these drawbacks. A hardening-type nonlinear tuned energy harvester with excited dynamic magnifier can achieve higher peak power, greater power per unit mass, and wider bandwidth without the need for retuning and for a minimal added cost as compared to the uncoupled harvester. Most importantly, the addition of a dynamic energy harvester also significantly improves performance in the frequency range of coexisting solutions by expanding the basin of attraction for the larger amplitude solution.

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.

Orbit Jumps of Monostable Energy Harvesters by a Bidirectional Energy Conversion Circuit

2019 ◽  
Author(s):  
Jiahua Wang ◽  
Bao Zhao ◽  
Junrui Liang ◽  
Wei-Hsin Liao
Keyword(s):  
Energy Harvesting ◽  
Energy Conversion ◽  
Vibration Amplitude ◽  
Energy Harvester ◽  
High Energy ◽  
Wide Frequency Range ◽  
Energy Harvesters ◽  
Novel Approach ◽  
Switch Control ◽  
Nonlinear Energy

Abstract Nonlinear energy harvesters have been widely studied in the last decade. Their broad bandwidth and relatively high power output contribute to energy harvesting applications. However, the coexisting multiple orbits brought by the nonlinearity weaken the performance of nonlinear energy harvesters. This paper proposes to achieve orbit jumps of monostable energy harvesters by a bidirectional energy conversion circuit. Changing the switch control sequence in the bidirectional energy conversion circuit facilitates it with both the energy harvesting and vibration exciting functions. Thus, a nonlinear energy harvester in connection with the circuit can harness ambient energy as well as excite itself, through energy harvesting and vibration exciting modes separately. Based on the concept of vibration exciting, the energy saved in the storage is used to stimulate the piezoelectric transducer for a larger vibration amplitude, which enables orbit jumps. The working mechanism of the circuit is introduced. Experimental setup of a monostable energy harvester has been developed to validate the proposed method. The monostable system can be stimulated to high-energy orbit from a small vibration amplitude by the vibration exciting mode of the circuit. It is also revealed that the method can achieve orbit jumps in a wide frequency range within the hysteresis area. Evaluations on energy consumption and energy gain show that the sacrificed energy can be quickly recovered. A novel approach for orbit jumps of monostable energy harvesters is performed so as to open new opportunities for monostable energy harvesters.

Towards Optimizing DC Loads for Power Generation From Arbitrarily Excited Nonlinear Vibration Energy Harvesters

2017 ◽  
Author(s):  
Quanqi Dai ◽  
Ryan L. Harne
Keyword(s):  
Power Generation ◽  
Energy Harvester ◽  
Load Resistance ◽  
Harmonic Excitation ◽  
Vibration Energy ◽  
Energy Harvesters ◽  
Dc Power ◽  
Resistive Loads ◽  
Periodic Components ◽  
Nonlinear Energy

In order to effectively take advantage of stiffness nonlinearities in vibration energy harvesters, the harvesters must be appropriately designed to ensure optimum direct current (DC) power generation. Yet, such optimization has only previously been investigated for alternating current (AC) power generation although most electronics demand DC power for their functioning. Moreover, real world excitations contain stochastic contributions combined with periodic components that challenges conventional approaches of investigation that only give attention to the harmonic excitation parts. To fill in the knowledge gap, this research undertakes comprehensive simulations to begin formulating conclusive understanding on the relationships between rectified power generation and nonlinear energy harvester system characteristics when the platforms are subjected to realistic combinations of harmonic and stochastic excitations. According to the simulation results, the rectified power demonstrates clear dependence on the load resistance in the unique limiting cases of complete or no stochastic excitation. When the excitation vibrations include both harmonic and stochastic components, the optimal resistance to maximize DC power exhibits a smoothly correlated but nonlinear change between the limiting case values of the resistance. The results of this investigation provide direct evidence of the intricate relationships among peak DC power, optimal resistive loads, and the nonlinear energy harvester design, and encourage continued study for direct analytical expressions that define such relationships.

scholarly journals Dynamics of a nonlinear energy harvester with subharmonic responses

2021 ◽  
Vol 1736 ◽  
pp. 012032
Author(s):  
G Litak ◽  
B Ambrożkiewicz ◽  
P Wolszczak
Keyword(s):  
Energy Harvester ◽  
Nonlinear Energy
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