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An electromechanical finite element model for piezoelectric energy harvester plates

MARQUI JUNIOR, Carlos De; ERTURK, Alper; INMAN, Daniel J.
Fonte: ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD Publicador: ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
Português
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Vibration-based energy harvesting has been investigated by several researchers over the last decade. The goal in this research field is to power small electronic components by converting the waste vibration energy available in their environment into electrical energy. Recent literature shows that piezoelectric transduction has received the most attention for vibration-to-electricity conversion. In practice, cantilevered beams and plates with piezoceramic layers are employed as piezoelectric energy harvesters. The existing piezoelectric energy harvester models are beam-type lumped parameter, approximate distributed parameter and analytical distributed parameter solutions. However, aspect ratios of piezoelectric energy harvesters in several cases are plate-like and predicting the power output to general (symmetric and asymmetric) excitations requires a plate-type formulation which has not been covered in the energy harvesting literature. In this paper. an electromechanically coupled finite element (FE) plate model is presented for predicting the electrical power output of piezoelectric energy harvester plates. Generalized Hamilton`s principle for electroelastic bodies is reviewed and the FE model is derived based on the Kirchhoff plate assumptions as typical piezoelectric energy harvesters are thin structures. Presence of conductive electrodes is taken into account in the FE model. The predictions of the FE model are verified against the analytical solution for a unimorph cantilever and then against the experimental and analytical results of a bimorph cantilever with a tip mass reported in the literature. Finally...

Influence of pattern gradation on the design of piezocomposite energy harvesting devices using topology optimization

Vatanabe, Sandro Luis; Paulino, Gláucio Hermógenes; Silva, Emilio Carlos Nelli
Fonte: ELSEVIER SCI LTD; OXFORD Publicador: ELSEVIER SCI LTD; OXFORD
Tipo: Artigo de Revista Científica
Português
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Piezoelectric materials can be used to convert oscillatory mechanical energy into electrical energy. Energy harvesting devices are designed to capture the ambient energy surrounding the electronics and convert it into usable electrical energy. The design of energy harvesting devices is not obvious, requiring optimization procedures. This paper investigates the influence of pattern gradation using topology optimization on the design of piezocomposite energy harvesting devices based on bending behavior. The objective function consists of maximizing the electric power generated in a load resistor. A projection scheme is employed to compute the element densities from design variables and control the length scale of the material density. Examples of two-dimensional piezocomposite energy harvesting devices are presented and discussed using the proposed method. The numerical results illustrate that pattern gradation constraints help to increase the electric power generated in a load resistor and guides the problem toward a more stable solution. (C) 2012 Elsevier Ltd. All rights reserved.; FAPESP (Sao Paulo State Foundation Research Agency); FAPESP (Sao Paulo State Foundation Research Agency) [2008/57086-6]; CNPq (National Council for Research and Development...

Computational and experimental characterization of a low-cost piezoelectric valveless diaphragm pump

Choi, Andres; Vatanabe, Sandro Luis; Lima, Cicero Ribeiro de; Silva, Emilio Carlos Nelli
Fonte: SAGE PUBLICATIONS LTD; LONDON Publicador: SAGE PUBLICATIONS LTD; LONDON
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
38.440166%
Flow pumps act as important devices in areas such as Bioengineering, Medicine, and Pharmacy, among other areas of Engineering, mainly for delivering liquids or gases at small-scale and precision flow rate quantities. Principles for pumping fluids based on piezoelectric actuators have been widely studied, since they allow the construction of pump systems for displacement of small fluid volumes with low power consumption. This work studies valveless piezoelectric diaphragm pumps for flow generation, which uses a piezoelectric ceramic (PZT) as actuator to move a membrane (diaphragm) up and down as a piston. The direction of the flow is guaranteed by valveless configuration based on a nozzle-diffuser system that privileges the flow in just one pumping direction. Most research efforts on development of valveless flow pump deal either with computational simulations based on simplified models or with simplified physical approaches based on analytical models. The main objective of this work is the study of a methodology to develop a low-cost valveless piezoelectric diaphragm flow pump using computational simulations, parametric study, prototype manufacturing, and experimental characterization. The parametric study has shown that the eccentricity of PZT layer and metal layer plays a key role in the performance of the pump.; FAPESP (Sao Paulo State Foundation Research Agency); FAPESP (Sao Paulo State Foundation Research Agency) [2004/14675-0...

Análise numérica de um transdutor piezelétrico de potência para processamento de termoplásticos têxteis. ; Numerical analysis of a high power piezoelectric transducer for thermoplastic textiles procesing.

Silva, João Batista da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 09/02/2006 Português
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38.63081%
Este trabalho apresenta um estudo de transdutores piezelétricos de potência usados em máquinas de estampagem e soldagem de tecidos sintéticos por ultra-som, através de modelos de elementos finitos implementados no software ANSYS e verificações experimentais. O transdutor é do tipo sanduíche e está acoplado a um amplificador mecânico e a um sonotrodo. Os comportamentos elétrico e vibracional do transdutor tipo sanduíche foram analisados em relação à quantidade de discos de piezocerâmicas em modelos axi-simétricos com quatro e oito discos. Comparam-se os resultados numéricos da resposta em frequência da impedância elétrica e do coeficiente de acoplamento eletromecânico com resultados experimentais de protótipos. Apresentam-se também análises numéricas do comportamento vibracional do amplificador mecânico e de dois tipos de sonotrodos, um cilíndrico e outro com o formato de uma lâmina larga, usados no processo de corte e soldagem de tecidos por ultra-som. É feita uma análise da distribuição de amplitude de vibração ao longo da face de trabalho dos dois sonotrodos. Os resultados simulados são comparados com os resultados experimentais de uma varredura feita na superfície de trabalho de cada protótipo usando-se um vibrômetro laser Doppler. Mostra-se que a vibração na face do sonotrodo cilíndrico ocorre com maior amplitude em uma região na sua borda. Considerando que para o processamento adequado do tecido é necessário que todos os pontos ao longo da face de trabalho do sonotrodo vibrem com a mesma amplitude...

Método de otimização topológica aplicado ao projeto de sonotrodos para transdutores piezelétricos.; Topology optimization method applied to the design of transducers sonotrodos piezoelectric.

Kiyono, César Yukishigue
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/03/2008 Português
Relevância na Pesquisa
39.014243%
Este trabalho tem por finalidade desenvolver um método baseado em Otimização Topológica para projetar uma estrutura mecânica, chamada de sonotrodo, acoplada a um transdutor piezelétrico de potência (dispositivo mecânico capaz de transformar energia elétrica em deformação mecânica ou vice-versa). Um sonotrodo é uma estrutura utilizada para transmitir vibrações mecânicas de um transdutor piezelétrico, ajustando a amplitude e a distribuição dos deslocamentos gerados por essa vibração para obedecer aos requisitos do projeto do transdutor. Dentre as aplicações de transdutores piezelétricos utilizando sonotrodos, pode-se citar sonares para navegação, limpeza e solda ultrassônica, tomografia acústica, furadeiras ultrassônicas, corte ultrassônico de tecidos, etc. Os requisitos de projeto do sonotrodo variam para cada aplicação, desde a necessidade de se obter o deslocamento máximo em um único ponto do sonotrodo até a uniformização do deslocamento de um plano inteiro da estrutura. Para a obtenção do resultado ótimo, neste trabalho são aplicadas técnicas de Otimização Topológica (OT). OT é um procedimento para projetar o leiaute ótimo de estruturas distribuindo material dentro de uma região fixa. O método de OT é implementado utilizando a Programação Linear Seqüencial (PLS) como algoritmo de otimização...

Projeto de materiais piezocompósitos baseados no conceito de gradação funcional utilizando o método de otimização topológica.; Design of piezocomposite materials based on functionally graded concept by means of topology optimization method.

Vatanabe, Sandro Luis
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 09/11/2012 Português
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38.695032%
Um material piezocompósito é resultante da combinação de um material piezelétrico com outros materiais não-piezelétricos, oferecendo vantagens substanciais em relação aos materiais piezelétricos convencionais. Diferentes propriedades efetivas podem ser obtidas alterando-se a fração de volume dos constituintes ou a própria topologia da célula unitária do piezocompósito. Materiais com Gradação Funcional (MGF) são materiais compósitos avançados, projetados de tal forma que sua composição varie gradualmente numa direção espacial. A vantagem do conceito MGF é não apresentar interface convencional entre os materiais da inclusão e da matriz, reduzindo assim um problema comum em materiais compósitos laminados, como por exemplo, o surgimento de concentração de tensões mecânicas. O Método de Otimização Topológica (MOT) é uma técnica computacional utilizada para se determinar a distribuição de materiais em uma estrutura ou material de forma sistemática, a fim de se extremizar uma determinada função objetivo. Assim, esse trabalho propõe uma metodologia sistemática e genérica para o projeto de materiais piezocompósitos com gradação funcional (MPGF) utilizando o MOT, tanto para aplicações quasi-estáticas...

Avaliação experimental de um sistema não linear para extração de energia através de vibrações utilizando material piezelétrico

Carvalho, Felipe Carmo
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Dissertação de Mestrado Formato: 113 f. : il.
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Pós-graduação em Engenharia Mecânica - FEIS; In order to meet the need for alternative energy sources to power autonomous microelectronic systems, studies have focused on the use of piezoelectric materials to transform energy derived from mechanical vibrations into electrical energy. Once the power delivered by the cantilever beams with piezoelectric materials are insufficient to power electronic devices autonomously, extraction techniques, conversion and energy storage was used to optimize the final accumulated energy. Considering that, this work aims at the optimization of an extractor system energy through vibrations using piezoelectric material, maximizing the power extracted and improving system performance. To this end, conditions of linearity and non-linearity in the mechanical system, as well as designed and tested converter circuits were analyzed. The best setup for electromechanical energy extraction, was used to feed an autonomous system. Two different power consumption-monitoring systems were designed to assess the limitation and potentialities of the proposed alternative for energy harvesting; Afim de suprir a necessidade por fontes alternativas de energia para a alimentação de sistemas microeletrônicos autônomos...

Process intensification and optimization for hydroxyapatite nanoparticles production

Castro, Filipa
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em 28/05/2012 Português
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27.475159%
Nanoparticles are of particular interest in biomedical applications since their critical size dimensions are close to cells and biological molecules. As they exhibit a variety of size- and shape dependent physical and chemical properties, a very good control of the reaction conditions is the key to obtain particles with desired characteristics. Conventional approaches for nanoparticles synthesis are based on wet chemical synthesis in stirred tank. But this kind of system generally yields particles with rather broad size distributions because of the low mixing efficiency and wide residence time distributions. Miniaturization of synthesis systems offers many advantages, including cost saving from reduced consumption of reagents and safer operation since the process consumes much reduced hazardous chemical. Further, transfer processes, mixing of reactants as well as residence time are fast in miniaturized systems, which is favorable for the generation of nanosized particles with a narrow size distribution. The present work aims at the production of hydroxyapatite (HAp) Ca10(PO4)6(OH)2 nanocrystals at physiological conditions of temperature and pH, with controlled size distribution and high biocompatibility, making them suitable for application in bone replacement. For this...

Optimization of Sensing and Feedback Control for Vibration/Flutter of Rotating Disk by PZT Actuators via Air Coupled Pressure

Yan, Tianhong; Xu, Xinsheng; Han, Jianqiang; Lin, Rongming; Ju, Bingfeng; Li, Qing
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 10/03/2011 Português
Relevância na Pesquisa
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In this paper, a feedback control mechanism and its optimization for rotating disk vibration/flutter via changes of air-coupled pressure generated using piezoelectric patch actuators are studied. A thin disk rotates in an enclosure, which is equipped with a feedback control loop consisting of a micro-sensor, a signal processor, a power amplifier, and several piezoelectric (PZT) actuator patches distributed on the cover of the enclosure. The actuator patches are mounted on the inner or the outer surfaces of the enclosure to produce necessary control force required through the airflow around the disk. The control mechanism for rotating disk flutter using enclosure surfaces bonded with sensors and piezoelectric actuators is thoroughly studied through analytical simulations. The sensor output is used to determine the amount of input to the actuator for controlling the response of the disk in a closed loop configuration. The dynamic stability of the disk-enclosure system, together with the feedback control loop, is analyzed as a complex eigenvalue problem, which is solved using Galerkin’s discretization procedure. The results show that the disk flutter can be reduced effectively with proper configurations of the control gain and the phase shift through the actuations of PZT patches. The effectiveness of different feedback control methods in altering system characteristics and system response has been investigated. The control capability...

Structure Optimization of a Grain Impact Piezoelectric Sensor and Its Application for Monitoring Separation Losses on Tangential-Axial Combine Harvesters

Liang, Zhenwei; Li, Yaoming; Zhao, Zhan; Xu, Lizhang
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 14/01/2015 Português
Relevância na Pesquisa
28.13688%
Grain separation losses is a key parameter to weigh the performance of combine harvesters, and also a dominant factor for automatically adjusting their major working parameters. The traditional separation losses monitoring method mainly rely on manual efforts, which require a high labor intensity. With recent advancements in sensor technology, electronics and computational processing power, this paper presents an indirect method for monitoring grain separation losses in tangential-axial combine harvesters in real-time. Firstly, we developed a mathematical monitoring model based on detailed comparative data analysis of different feeding quantities. Then, we developed a grain impact piezoelectric sensor utilizing a YT-5 piezoelectric ceramic as the sensing element, and a signal process circuit designed according to differences in voltage amplitude and rise time of collision signals. To improve the sensor performance, theoretical analysis was performed from a structural vibration point of view, and the optimal sensor structural has been selected. Grain collide experiments have shown that the sensor performance was greatly improved. Finally, we installed the sensor on a tangential-longitudinal axial combine harvester, and grain separation losses monitoring experiments were carried out in North China...

Modeling and design of a MEMS piezoelectric vibration energy harvester; Microelectromechanical systems piezoelectric vibration energy harvester

Du Toit, Noël Eduard
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 244 p.; 13606832 bytes; 13622884 bytes; application/pdf; application/pdf
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The modeling and design of MEMS-scale piezoelectric-based vibration energy harvesters (MPVEH) are presented. The work is motivated by the need for pervasive and limitless power for wireless sensor nodes that have application in structural health monitoring, homeland security, and infrastructure monitoring. A review of prior milli- to micro-scale harvesters is provided. Common ambient low-level vibration sources are characterized experimentally. Coupled with a dissipative system model and a mechanical damping investigation, a new scale-dependent operating frequency selection scheme is presented. Coupled electromechanical structural models are developed, based on the linear piezoelectric constitutive description, to predict uni-morph and bi-morph cantilever beam harvester performance. Piezoelectric coupling non-intuitively cancels from the power prediction under power-optimal operating conditions, although the voltage and current are still dependent on this property. Piezoelectric material selection and mode of operation ([3-1] vs. [3-3]) therefore have little effect on the maximum power extracted. The model is verified for resonance and off-resonance operation by comparison to new experimental results for a macro-scale harvester. Excellent correlation is obtained away from resonances in the small-strain linear piezoelectric regime. The model consistently underpredicts the response at resonances due to the known non-linear piezoelectric constitutive response (higher strain regime). Applying the model...

Towards and embeddable structural health monitoring sensor : design and optimization of MEMS piezoelectric vibration energy harvesters; Towards an embeddable composite health monitoring sensor : design and optimization of MEMS piezoelectric vibration energy harvesters

Mracek, Anna Marie
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 173 p.; 10446402 bytes; 10983471 bytes; application/pdf; application/pdf
Português
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Wireless structural health monitoring (SHM) has gained considerable interest as a potential method of reducing aircraft maintenance costs while increasing safety. Distributed power supplies for the sensing nodes are needed for a practical implementation of this technique. Vibrational energy harvesting using MEMS piezoelectric resonant devices is an appealing solution to this challenge due to their relatively high potential for power generation (compared to other harvesting techniques) and capacity to be integrated into the microfabrication procedure of the remainder of the SHM node. A comprehensive review of energy harvesting devices, particularly piezoelectric harvesters, is presented, including characterization of previous devices in terms of key power performance metrics. An existing coupled electromechanical model is presented and modified for use in optimization studies with both {3-1} Mode and {3-3} Mode piezoelectric cantilevered beam configurations. The modified model accurately represents published experimental results. A series of design optimization studies is presented for four devices operating in an aircraft vibration environment.; (cont.) Untapered bimorph {3-1} Mode and unimorph {3-3} Mode MEMS devices with large proof masses...

Controle ativo de ruído empregando placas retangulares com atuadores piezoelétricos distribuídos; Active Noise Control using Rectangular Plates with Distributed Piezoelectric Actuators

Santana, Danuza Cristina
Fonte: Universidade Federal de Uberlândia Publicador: Universidade Federal de Uberlândia
Tipo: Dissertação
Português
Relevância na Pesquisa
48.714595%
O presente trabalho tem por objetivo a realização de um estudo abrangente sobre a utilização de placas finas retangulares instrumentadas com pastilhas piezoelétricas, como fontes de controle ativo de ruído. Para tanto é desenvolvida a modelagem analítica do comportamento vibratório de placas finas, retangulares e uniformes, com base na teoria de Kirchhoff. É desenvolvida a formulação analítica que descreve a interação placa-atuadores piezoelétricos. Considerando como fonte primária uma onda plana harmônica oblíqua incidente sobre a placa, é desenvolvida a modelagem do comportamento vibratório de placas excitadas por fontes sonoras. Após estes desenvolvimentos, realiza-se o estudo da radiação sonora emitida por placas retangulares em campo distante baseada na integral de Rayleigh. Utiliza-se então um sistema de controle ótimo não adaptativo do tipo feedforward a fim de otimizar a tensão elétrica de ativação dos atuadores piezoelétricos de maneira que a potência sonora radiada em campo distante seja minimizada. É ainda proposto um procedimento de otimização do posicionamento dos atuadores piezoelétricos utilizando Algoritmos Genéticos. Com base nos desenvolvimentos teóricos, são realizadas numerosas simulações computacionais tendo em vista a avaliação da teoria desenvolvida. Nestas simulações é avaliada a influência de diferentes parâmetros...

Physical systems for the active control of transformer noise

Li, Xun
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 3274516 bytes; 58288 bytes; application/pdf; application/pdf
Publicado em //2000 Português
Relevância na Pesquisa
18.611343%
Traditional means of controlling sound radiated by electrical power transformers involve the construction of large expensive barriers or full enclosures, which cause maintainability and cooling problems. One promising alternative is to use active noise control to cancel the noise. This thesis is concerned with one of the many problems which need to be investigated to develop a practical active noise cancellation system for transformers. This work, in particular, is concerned with the physical system design which includes the selection of the control source types and the evaluation of the near-field sensing strategies. Loudspeakers have been widely used in the past as an acoustic source for canceling transformer noise. The principal disadvantage of using loudspeakers is that to achieve global noise control, a large number, driven by a multi-channel controller, are required. However, if large panels are used in place of loudspeakers as control sources, it is possible that the number of the control sources and complexity of the controller could be reduced substantially. In addition to reducing the number of control sources and simplifying their application, panel sound sources could also overcome some disadvantages of the loudspeakers...

MEMS-based waste vibrational energy harvesters

Hogue, Daniel B.; Gregory, Sarah M.
Fonte: Monterey, California: Naval Postgraduate School Publicador: Monterey, California: Naval Postgraduate School
Português
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Approved for public release; distribution is unlimited; The piezoelectric effect is a phenomenon where strain on a piezoelectric crystal structure causes potential difference at its ends. By merging piezoelectric materials and microelectromechanical systems (MEMS), mechanical vibration could cause the necessary displacement in MEMS to create a potential difference that could be used to power electronic devices. Developing new sustainable energy sources and using energy more efficiently is at the forefront of several research initiatives and is a clear priority for the Department of the Navys strategic planning. This thesis aims to design a vibrational energy harvesting MEMS device to harness vibrational waste energy with the goal of producing power for naval applications. The development and widespread use of vibrational harvesting MEMS would aid the effort to meet each of these goals in the Department of the Navy. Any shore based, seagoing, or expeditionary mechanical platform could serve as a kinetic energy source for vibration energy harvesting MEMS. This thesis investigates the physics, materials, design, optimization, and microfabrication process in the creation of such a device. Time-dependent finite element models for two designs have been developed...

Optimal design of piezoelectric materials for maximal energy harvesting

Nelson, Russell J.
Fonte: Monterey, California: Naval Postgraduate School Publicador: Monterey, California: Naval Postgraduate School
Tipo: Tese de Doutorado
Português
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58.92796%
Approved for public release; distribution is unlimited; The military’s dependence on fossil fuels for electric power production in isolated settings is both logistically and monetarily expen-sive. Currently, the Department of Defense is actively seeking alternative methods to produce electricity, thus decreasing dependence on fossil fuels and increasing combat power.We believe piezoelectric generators have the ability to contribute to military applications of alternative electrical power generation in isolated and austere conditions. In this paper, we use three and six variable mathemat-ical models to analyze piezoelectric generator power generation capabilities. Using mk factorial sampling, nearly orthogonal and balanced Latin hypercube (NOBLH) design, and NOBLH iterative methods, we find optimal solutions to maximize piezoelectric gen-erator power output. We further analyze our optimal results using robustness analysis techniques to determine the sensitivity of our models to variable precision. With our results, we provide analysts and engineers the optimal designs involving material parameters in the piezoelectric generator, as well as the generator’s environment, in order to maximize electric output.; ; Captain, United States Army

Vibration reduction of composite plates by piezoelectric patches using a modified artificial bee colony algorithm

Ghashochi-Bargh,Hadi; Sadr,Mohammad Homayoune
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 Português
Relevância na Pesquisa
27.909412%
In Current paper, power consumption and vertical displacement optimization of composite plates subject to a step load are carried out by piezoelectric patches using the modified multi-objective Elitist-Artificial Bee Colony (E-ABC) algorithm. The motivation behind this concept is to well balance the exploration and exploitation capability for attaining better convergence to the optimum. In order to reduce the calculation time, the elitist strategy is also used in Artificial Bee Colony algorithm. The voltages of patches, plate length/width ratios, ply angles, plate thickness/length ratios, number of layers and edge conditions are chosen as design variables. The formulation is based on the classical laminated plate theory (CLPT) and Hamilton's principle. The performance of the new ABC approach is compared with the PSO algorithm and shows the good efficiency of the new ABC approach. To check the validity, the transient responses of isotropic and orthotropic plates are compared with those available in the literature and show a good agreement.

Fluid-solid-electric lock-in of energy-harvesting piezoelectric flags

Xia, Yifan; Michelin, Sebastien; Doare, Olivier
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 09/01/2015 Português
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27.909412%
The spontaneous flapping of a flag in a steady flow can be used to power an output circuit using piezoelectric elements positioned at its surface. Here, we study numerically the effect of inductive circuits on the dynamics of this fluid-solid-electric system and on its energy harvesting efficiency. In particular, a destabilization of the system is identified leading to energy harvesting at lower flow velocities. Also, a frequency lock-in between the flag and the circuit is shown to significantly enhance the system's harvesting efficiency. These results suggest promising efficiency enhancements of such flow energy harvesters through the output circuit optimization.; Comment: 8 pages, 8 figures, to appear in Physical Review Applied

Optimization of Piezoelectric Electrical Generators Powered by Random Vibrations

Lefeuvre, E.; Badel, A.; Richard, C.; Petit, L.; Guyomar, D.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 21/11/2007 Português
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This paper compares the performances of a vibrationpowered electrical generators using PZT piezoelectric ceramic associated to two different power conditioning circuits. A new approach of the piezoelectric power conversion based on a nonlinear voltage processing is presented and implemented with a particular power conditioning circuit topology. Theoretical predictions and experimental results show that the nonlinear processing technique may increase the power harvested by a factor up to 4 compared to the Standard optimization technique. Properties of this new technique are analyzed in particular in the case of broadband, random vibrations, and compared to those of the Standard interface.; Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions)

Control of Vibratory Energy Harvesters in the Presence of Nonlinearities and Power-Flow Constraints

Cassidy, Ian Lerner
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2012 Português
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38.485166%

Over the past decade, a significant amount of research activity has been devoted to developing electromechanical systems that can convert ambient mechanical vibrations into usable electric power. Such systems, referred to as vibratory energy harvesters, have a number of useful of applications, ranging in scale from self-powered wireless sensors for structural health monitoring in bridges and buildings to energy harvesting from ocean waves. One of the most challenging aspects of this technology concerns the efficient extraction and transmission of power from transducer to storage. Maximizing the rate of power extraction from vibratory energy harvesters is further complicated by the stochastic nature of the disturbance. The primary purpose of this dissertation is to develop feedback control algorithms which optimize the average power generated from stochastically-excited vibratory energy harvesters.

This dissertation will illustrate the performance of various controllers using two vibratory energy harvesting systems: an electromagnetic transducer embedded within a flexible structure, and a piezoelectric bimorph cantilever beam. Compared with piezoelectric systems, large-scale electromagnetic systems have received much less attention in the literature despite their ability to generate power at the watt--kilowatt scale. Motivated by this observation...