1,372 research outputs found
Design and characterization of a fractal-inspired multi-frequency piezoelectric energy converter
Get PDFA promising harvesting technique, in terms of simplicity and efficiency, is the conversion of ambient kinetic energy through piezoelectric materials. This work aims to design and investigate a piezoelectric converter conform to a fractal-inspired, multi-frequency structure previously presented by the author. A physical prototype of the converter is built and experimentally examined, up to 120 Hz, in terms of modal response and power output. Three eigenfrequencies are registered and the power output is particularly good at the fundamental eigenfrequency. Also the effect of the resistive load applied to the converter is investigated
A fractal-inspired multi-frequency piezoelectric energy converter: computational and experimental characterization
No full textIn order to develop self-powered wireless sensor nodes, many energy harvesting devices, able to convert freely available ambient energy into electrical energy, have been proposed in the literature. A promising technique, in terms of simplicity and high conversion efficiency, is the harvesting of ambient kinetic energy through piezoelectric materials.The aim of this work is to design and investigate the modal response and the power output of a fractal-inspired, multi-frequency, piezoelectric energy converter, previously presented by the author. Two are the steps of the work. First, a computational modal analysis of the converter is performed. Second, a physical prototype of the converter is built and its eigenfrequencies and power generation under different resistive loads are experimentally examined in the range between 0 and 120 Hz. The converter exhibits three eigenfrequencies and a good power output, in particular at the first eigenfrequency
Experimental Modal Analysis of Fractal-Inspired Multi-Frequency Piezoelectric Energy Converters
No full textAn important issue in the field of energy harvesting through piezoelectric materials is the design of simple and efficient structures which are multi-frequency in the ambient vibration range. This paper deals with the experimental assessment of four fractal-inspired multi-frequency structures for piezoelectric energy harvesting. These structures, thin plates of square shape, were proposed and numerically analyzed, with regard to their modal response, in a previous work by the author. The aim of this work is twofold. First, to assess the modal response of these structures through an experimental investigation. Second, to evaluate, through computational simulation, the performance of a piezoelectric converter prototype relying on one of these fractal-inspired structures. The four fractal-inspired structures are examined experimentally in the range between 0 and 100 Hz, both with regard to eigenfrequencies and eigenmodes. In the same frequency range are investigated the modal response and power output of a converter prototype
Experimental comparison between a fractal-inspired multi-frequency piezoelectric energy converter and a traditional converter
No full textHarvesting energy from ambient vibrations in order to power autonomous sensors is a challenging issue. The aim of this work is to compare the power output from an innovative multi-frequency fractal-inspired piezoelectric converter to that from a traditional multi-cantilever piezoelectric converter. The converters are designed in order to give the same eigenfrequencies in a given range and a prototype of both is built using commercial materials. The experimental tests investigate both the effect of the acceleration and of the resistive load applied to the converters for each of the three eigenfrequencies in the range between 0 and 120 Hz. The fractal-inspired converter exhibits a significantly higher specific output power at the first and third of the eigenfrequencies investigated.Harvesting energy from ambient vibrations in order to power autonomous sensors is a challenging issue. The aim of this work is to compare the power output from an innovative multi-frequency fractal-inspired piezoelectric converter to that from a traditional multi-cantilever piezoelectric converter. The converters are designed in order to give the same eigenfrequencies in a given range and a prototype of both is built using commercial materials. The experimental tests investigate both the effect of the acceleration and of the resistive load applied to the converters for each of the three eigenfrequencies in the range between 0 and 120 Hz. The fractal-inspired converter exhibits a significantly higher specific output power at the first and third of the eigenfrequencies investigated. Copyright © 2013 by Alstom Technologie AG
A Belleville-Spring Based Piezoelectric or Electromagnetic Energy Harvester
No full textEnergy harvesting from kinetic ambient energy requires converters able to efficiently operate in the low frequency range. A limit of the solutions proposed in the literature, both electromagnetic and piezoelectric, is their operating frequency, which generally ranges from about 50 to 300 Hz. To overcome these limitations, this work proposes an innovative energy harvester exploiting two counteracting Belleville springs. Thanks to the peculiar height to thickness ratio of the springs a highly compliant elastic system is obtained, which can be used either for electromagnetic or piezoelectric harvesting. The harvester is modelled analytically and numerically both with regard to the force-displacement and to the modal response. The experimental validation of the harvester, highlights a noticeable power output but at a higher eigenfrequency than expected
A tunable multi-arm electromagnetic pendulum for ultra-low frequency vibration energy harvesting
No full textAutonomous electronic devices and sensors are essential to reduce expensive maintenance,
increasing job security and reliability, avoiding battery replacements and wired systems.
Industrial systems and civil structures vibrate dissipating an important amount of energy that
can be harvested to power small devices. This work continues and extends a previous work from
the authors (Castagnetti 2019 Meccanica 54 749–60). Here we improved that initial
configuration by proposing a tunable multi-arm electromagnetic pendulum for ultra-low
frequency vibrations energy harvesting. This configuration features five electromagnetic
converters and a magnetic spring, each supported by a pendulum arm with different length:
when excited by external vibrations, this six arms frame is free to oscillate around a central
pivot. The paper starts from conceptual design, includes a detailed multiphysics dynamic
simulation implemented with Matlab Simscape software, presents the prototype development
through three-dimensional printing and experimental validation. Systematic experimental tests
investigated different pendulum configurations for three stiffness levels of the magnetic spring
and confirmed both the ultra-low frequency response (from 2 to 10 Hz), as predicted by the
dynamic simulation, and the good voltage and power outputs. Specifically, for the higher
stiffness of the magnetic spring, corresponding to an oscillation frequency of about 9.5 Hz, the
power output was up to 8.4 mW and the output voltage of about 2 Volt
Fractal-inspired multi-frequency structures for piezoelectric harvesting of ambient kinetic energy
No full textEnergy harvesting devices capable of converting freely-available ambient energy into electrical energy have received significant attention recently. Ambient kinetic energy is particularly attractive for conversion since it is almost ubiquitous and easily accessible. Piezoelectric energy harvesting devices are promising due to their simple configuration and high conversion efficiency. This paper studies multifrequency structures for piezoelectric energy harvesting of ambient kinetic energy, inspired by fractal geometry. Identifying such structures that are simple and efficient is challenging. We propose four fractal-inspired structures and we examine them at both micro and macroscales. We calculate their frequency response up to 100 Hz with computational modeling, and we also examine the effect of the fractal geometry iteration level. We use a cantilever plate example as a reference to validate computational results against analytical ones. A quantitative criterion to assess the harvesting efficiency of the proposed structures is introduced using the bending strain associated with each mode shape. Results show that a large number of eigenfrequencies is obtained, evenly distributed below 100 Hz, particularly in the macroscale. In addition, the iteration level of the fractal geometry affects the number and distribution of eigenfrequencies in the range of interest. Comparison with a conventional batch of cantilevers of the same size as the proposed structures shows noticeable improvement in electric charge generation
A piezoelectric based energy harvester with dynamic magnification
No full textEnergy harvesting from ambient vibrations exploiting piezoelectric materials is an efficient solution for the development of self-sustainable electronic nodes. This work presents a simple and innovative piezoelectric energy harvester, intrinsically including dynamic magnification and inspired by fractal geometry. After an initial design step, computational analysis and experimental validation show a very good frequency response with five eigenfrequencies below 100 Hz. Even if the piezoelectric transducers were put only on a symmetric half of the top surface of the structure, the energy conversion is good for all the eigenfrequencies investigated
A wideband fractal-inspired piezoelectric energy converter: design, simulation and experimental characterization
No full textIn order to develop self-powered wireless sensor nodes, many energy harvesting devices that are able to convert available ambient energy into electrical energy have been proposed in the literature. A promising technique, in terms of simplicity and high conversion efficiency, is the harvesting of ambient kinetic energy through piezoelectric materials. The aim of this work is to design and investigate the modal response and power output of a fractal-inspired, multi-frequency, piezoelectric energy converter. The converter is a square, thin sheet structure, characterized by a fractal geometry obtained through a pattern of cuts in the plate. There are two steps involved. First, a computational analysis of the converter is performed. Second, a physical prototype of the converter is built and its eigenfrequencies and power generation under different resistive loads are experimentally examined in the range from 0 to 120 Hz. The converter exhibits three eigenfrequencies and a good power output, particularly at the first eigenfrequency
A simply tunable electromagnetic pendulum energy harvester
No full textA fundamental issue for the advance of self-sustainable electronic systems and remote sensor is the development of energy harvesters able to efficiently convert ambient energy into electrical energy. This paper presents an innovative simply tunable pendulum electromagnetic energy harvester, starting from conceptual design, analysis of the mechanical system and electromagnetic converter, development, and experimental assessment. The proposed system has the peculiar feature of a magnetic spring to enhance the equilibrium whichever the orientation and enabling frequency tuning. A magnetic C-frame gives a constant magnetic field through a gap, which is crossed by the coils fixed to a free end of the pendulum. The prototype, about one cubic decimeter, provides a low frequency and simply tunable modal response, together with a significant output power
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