Design of a Vibration-Based Energy Harvester With Adjustable Natural Frequency

Author(s):  
Mohamed O. Mansour ◽  
Mustafa H. Arafa ◽  
Said M. Megahed

The recent years have witnessed a wealth of research on energy harvesting technologies. To maximize the output power, vibration-based energy harvesters are normally designed to have natural frequencies that match those of the excitation. This has spurred interest into the design of devices that possess tunable natural frequencies to cope with sources which exhibit varying frequencies. In this work, an energy harvester is proposed in the form of a base excited cantilever treated with a piezoelectric layer. The cantilever carries a tip mass in the form of a magnet which is placed in close proximity to another magnet with opposite polarity. Different values of axial tensions, and hence different natural frequencies, are obtained by adjusting the gap between the magnets. A dynamic model to predict the system performance is presented and verified experimentally. Based on the findings of this paper, natural frequencies ranging from 3.19–12 Hz were achieved.

Author(s):  
Mustafa H. Arafa

Vibration-based energy harvesters are usually designed to exhibit natural frequencies that match those of the excitation for maximum power output. This has spurred interest into the design of devices that respond to variable frequency sources. In this work, an electromagnetic energy harvester in the form of a base excited trapezoidal plate is proposed. The plate geometry is designed to achieve two closely spaced vibration modes in order to harvest energy across a broader bandwidth. The ensuing bending and twisting vibrations are utilized in this capacity by placing a magnet on the plate tip that moves past a stationary coil. A dynamic model is presented to predict the system performance and is verified experimentally.


2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Mustafa H. Arafa

Vibration-based energy harvesters are usually designed to exhibit natural frequencies that match those of the excitation for maximum power output. This has spurred interest into the design of devices that respond to variable frequency sources. In this work, an electromagnetic energy harvester in the form of a base excited trapezoidal plate is proposed. The plate geometry is designed to achieve two closely spaced vibration modes in order to harvest energy across a broader bandwidth. The ensuing bending and twisting vibrations are utilized in this capacity by placing a magnet on the plate tip that moves past a stationary coil. A dynamic model is presented to predict the system performance and is verified experimentally.


Author(s):  
M. H. Ansari ◽  
M. Amin Karami

A fan-folded piezoelectric energy harvester is designed to generate electricity using heartbeat vibrations. This energy harvester consists of several bimorph beams stacked on top of each other making a fan-folded shape. Each beam has a brass substrate and two piezoelectric patches attached on both sides of it. These beams are connected to each other by rigid beams. One end of the device is clamped to the wall and the other end is free to vibrate. A tip mass is placed at the free end to enhance the output power of the device and reduce the natural frequency of the system. High natural frequency is one major concern about the microscaled energy harvesters. The size for this energy harvester is 1 cm by 1 cm by 1 cm, which makes the natural frequency very high. By utilizing the fan-folded geometry and adding tip mass and link mass to the configuration, this natural frequency is reduced to the desired range. The generated electricity can be used to power up a pacemaker. If enough electricity is generated, the pacemaker operates without having a battery and the patient does not need to have a surgery every seven to ten years to have the battery replaced. The power needed for a pacemaker to operate is about 1 microwatt. In this paper, the natural frequencies and mode shapes of fan-folded energy harvesters with added tip mass and link mass are analytically derived. The electro-mechanical coupling has been included in the model and the expression for the multi-mode power frequency response function is calculated.


Author(s):  
D. Guo ◽  
X. F. Zhang ◽  
H. Y. Li ◽  
H. Li

Energy harvesting using piezoelectric materials is an alternative method for low power electronics, such as MEMS, wireless sensor network, portable devices, and nano structures, from extracting the ambient energy. Most piezoelectric energy harvesters are based on cantilever beams with laminated piezoelectric patches. To generate higher dynamic response of piezoelectric energy harvesters, tip mass is attached at the free end of the cantilever beams. Piezoelectric energy harvester array is another way to improve the power, i.e., installing a set of cantilever piezoelectric energy harvesters in close distance. In this research, a new design of piezoelectric energy harvester is proposed. The present design consists of an array of cantilever beams with permanent magnets at the free ends. The permanent magnets are introduced to transfer the excitation force to every cantilever beams. An experimental model is manufactured and experimental energy harvesting is carried out. Piezoelectric patches are laminated on clamped end of cantilever beams, and the permanent magnets are fixed at the free ends. All the magnets have opposite poles with each other to generate repelling force. Then these piezoelectric electric energy harvesters were connected to an AC/DC circuit and the power was measured. Also, the power of proposed piezoelectric energy harvester was compared with the piezoelectric harvesters without permanent magnets. The results show that, present design can generate higher power at the same excitation. Under the base excitation at the first natural frequency, the array of the cantilever beam show similar motion pattern, i.e., there is no phase difference between each other. At higher frequencies, the beams have a phase difference of π. Thus the crash between the cantilever beams can be effectively avoided. At lower excitation frequencies, the presented piezoelectric energy harvester vibration likes the first mode of a simple multi-degree-of-freedom system; and at higher excitation frequencies, the vibration of the presented piezoelectric vibrates like a second mode of a MDOF system.


Author(s):  
Shun Chen ◽  
David Eager ◽  
Liya Zhao

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.


Author(s):  
Sumin Seong ◽  
Christopher Mullen ◽  
Soobum Lee

This paper presents reliability-based design optimization (RBDO) and experimental validation of the purely mechanical nonlinear vibration energy harvester we recently proposed. A bi-stable characteristic was embodied with a pre-stressed curved cantilever substrate on which piezoelectric patches were laminated. The curved cantilever can be simply manufactured by clamping multiple beams with different lengths or by connecting two ends of the cantilever using a coil spring. When vibrating, the inertia of the tip mass activates the curved cantilever to cause snap-through buckling and makes the nature of vibration switch between two equilibrium positions. The reliability-based design optimization study for maximization of power density and broadband energy harvesting performance is performed. The benefit of the proposed design in terms of excellent reliability, design compactness, and ease of implementation is discussed. The prototype is fabricated based on the optimal design result and energy harvesting performance between the linear and nonlinear energy harvesters is compared. The excellent broadband characteristic of the purely mechanical harvester will be validated.


2016 ◽  
Vol 09 (05) ◽  
pp. 1650069 ◽  
Author(s):  
Yaoze Liu ◽  
Tongqing Yang ◽  
Fangming Shu

Since the piezoelectric properties were used for energy harvesting, almost all forms of energy harvester needs to be bonded with a mass block to achieve pre-stress. In this article, disc type piezoelectric energy harvester is chosen as the research object and the relationship between mass bonding area and power output is studied. It is found that if the bonding area is changed as curved, which is usually complanate in previous studies, the deformation of the circular piezoelectric ceramic is more uniform and the power output is enhanced. In order to test the change of the deformation, we spray several homocentric annular electrodes on the surface of a piece of bare piezoelectric ceramic and the output of each electrode is tested. Through this optimization method, the power output is enhanced to more than 11[Formula: see text]mW for a matching load about 24[Formula: see text]k[Formula: see text] and a tip mass of 30[Formula: see text]g at its resonant frequency of 139[Formula: see text]Hz.


Author(s):  
Swapnil Arawade ◽  
Ganesh Korwar

In this literature different biomechanical energy harvesters are reviewed. In the past years a lot of work reported on energy harvesting. Energy crisis is the main issue in front of human so it is essential to find new promising ways to fulfil the need of electricity. Wearable smart devices and small sensor require low electrical power so to power them biomechanical energy harvesters comes into picture. The innovative work done by the researchers in developing new biomechanical energy harvester is discussed and summarized.


2014 ◽  
Vol 953-954 ◽  
pp. 655-658 ◽  
Author(s):  
Guang Qing Shang ◽  
Hong Bing Wang ◽  
Chun Hua Sun

Energy harvesting system has become one of important areas of ​​research and develops rapidly. How to improve the performance of the piezoelectric vibration energy harvester is a key issue in engineering applications. There are many literature on piezoelectric energy harvesting. The paper places focus on summarizing these literature of mathematical modeling of piezoelectric energy harvesting, ranging from the linear to nonlinear, from early a single mechanical degree to piezoaeroelastic problems.


Author(s):  
Lin Dong ◽  
Frank T. Fisher

Vibration-based energy harvesting has been widely investigated to as a means to generate low levels of electrical energy for applications such as wireless sensor networks. However, due to the fact that vibration from the environment is typically random and varies with different magnitudes and frequencies, it is a challenge to implement frequency matching in order to maximize the power output of the energy harvester with a wider frequency bandwidth for applications where there is a time-dependent, varying source frequency. Possible solutions of frequency matching include widening the bandwidth of the energy harvesters themselves in order to implement frequency matching and to perform resonance-based tuning approach, the latter of which shows the most promise to implement a frequency matching design. Here three tuning strategies are discussed. First a two-dimensional resonant frequency tuning technique for the cantilever-geometry energy harvesting device which extended previous 1D tuning approaches was developed. This 2D approach could be used in applications where space constraints impact the available design space of the energy harvester. In addition, two novel resonant frequency tuning approaches (tuning via mechanical stretch and tuning via applied bias voltage, respectively) for electroactive polymer (EAP) membrane-based geometry energy harvesters was proposed, such that the resulting changes in membrane tension were used to tune the device for applications targeting variable ambient frequency environments.


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