Tesis sobre el tema "Electromechanical harvesting"
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Nagode, Clement Michel Jean. "Electromechanical Suspension-based Energy Harvesting Systems for Railroad Applications". Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/50611.
Texto completoThe focus of this research is on the development of vibration-based electromechanical energy harvesting systems that would provide electrical power in a freight car. With size and shape similar to conventional shock absorbers, these devices are designed to be placed in parallel with the suspension elements, possibly inside the coil spring, thereby maximizing unutilized space. When the train is in motion, the suspension will accommodate the imperfections of the track, and its relative velocity is used as the input for the harvester, which converts the mechanical energy to useful electrical energy.
Beyond developing energy harvesters for freight railcar primary suspensions, this study explores track wayside and miniature systems that can be deployed for applications other than railcars. The trackside systems can be used in places where electrical energy is not readily available, but where, however, there is a need for it. The miniature systems are useful for applications such as bicycle energy.
Beyond the design and development of the harvesters, an extensive amount of laboratory testing was conducted to evaluate both the amount of electrical power that can be obtained and the reliability of the components when subjected to repeated vibration cycles. Laboratory tests, totaling more than two million cycles, proved that all the components of the harvester can satisfactorily survive the conditions to which they are subjected in the field. The test results also indicate that the harvesters are capable of generating up to 50 Watts at 22 Vrms, using a 10-Ohm resistor with sine wave inputs, and over 30 Watts at peak with replicated suspension displacements, making them suitable to directly power onboard instruments or to trickle charge a battery.
Ph. D.
Erturk, Alper. "Electromechanical Modeling of Piezoelectric Energy Harvesters". Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/29927.
Texto completoPh. D.
VILLA, SARA MOON. "SOFT POLYMERIC NANOCOMPOSITES FOR ELECTROMECHANICAL CONVERSION". Doctoral thesis, Università degli Studi di Milano, 2022. http://hdl.handle.net/2434/933149.
Texto completoMateu, Sáez Maria Loreto. "Energy harvesting from human passive power". Doctoral thesis, Universitat Politècnica de Catalunya, 2009. http://hdl.handle.net/10803/48637.
Texto completoThe trends in technology allow the decrease in both size and power consumption of complex digital systems. This decrease in size and power gives rise to the concept of wearable devices which are integrated in everyday personal belongings like clothes, watch, glasses, et cetera. Power supply is a limiting factor in the mobility of the wearable device which gets restricted to the lifetime of the battery. Furthermore, due to the costs and inaccessible locations, the replacement or recharging of batteries is often not feasible for wearable devices integrated in smart clothes. Wearable devices are devices distributed in personal belongings and thus, an alternative for powering them is to harvest energy from the user. Therefore, the energy can be harvested, distributed and supplied over the human body. Wearable devices can create, like the sensors of a Wireless Sensor Network (WSN), a Body Area Network. A study of piezoelectric, inductive and thermoelectric generators that harvest passive human power is the main objective of this thesis. The physical principle of an energy harvesting generator is obviously the same no matter whether it is employed with an environmental or human body source. Nevertheless, the limitations related to low voltage, current and frequency levels obtained from human body sources bring new requirements to the energy harvesting topic that were not present in the case of the environment sources. This analysis is the motivation for this thesis. The type of input energy and transducer form a tandem since the election of one imposes the other. It is important that measurements are done in different parts of the human body while doing different physical activities to locate which positions and activities produce more energy. The mechanical coupling between the transducer and the human body depends on the location of the transducer and the activity that is done. A specific design taking this into account can increase more than a 200% the efficiency of the transducer as has been demonstrated with piezoelectric films located in the insoles of shoes. Acceleration measurements have been performed in different body locations and different physical activities, in order to quantify the amount of available energy associated with usual human movements. A system-level simulation has been implemented modeling the elements of an energy self-powered system. Physical equations have been used for the transducer in order to include the mechanical part of the system and electrical and behavioral models for the rest of the components. In this way, the process of the design of the complete application (including the load and an energy storage element when it is necessary) is simplified to achieve the expected requirements. Obviously, the load must be a low power consumption device as for example a RF transmitter. In this case, it is preferable to operate it in a discontinuous way without a battery as it is deduced from simulation results obtained. However, the evolution in low power transmission modules can change this conclusion depending mostly on the evolution of the power consumption in stand-by mode and the configuration time in transmission operation. It has been deduced from the analysis of inductive generators that time-domain analysis allows to calculate some magnitudes that are not available in frequency domain. For example, the maximum power can be calculated in frequency domain, but for energy harvesting applications it is more interesting to know the value of the recovered energy during a certain time, or the average power since the power generated by human activities can be highly discontinuous. It has been demonstrated that energy harvesting transducers are able to supply power to present-day low power electronic devices as was demonstrated with a RF transmitter powered by a thermogenerator that employs the temperature gradient between human body and the environment (3-5 K) and that it is able to sense and transmit data once every second.
ASKARI, MAHMOUD. "Electromechanical Modelling and Analysis of Piezoelectric Smart Structures: Energy Harvesting, Static and Dynamic Problems". Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2964794.
Texto completoGater, Brittany L. "The Hydrodynamics and Energetics of Bioinspired Swimming with Undulatory Electromechanical Fins". Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78377.
Texto completoMaster of Science
Animals interact with the world much differently than engineered systems, and can offer new and efficient ways to solve engineering problems, including underwater vehicles. To learn how to move an underwater vehicle in an environmentally conscious way, it is useful to study how a fish’s movements affect the manner in which it moves through the water. Through careful study, the principles involved can be implemented for an efficient, low-disturbance underwater vehicle. The particular fish chosen for in-depth study was the stingray, due to its maneuverability and ability to travel close to the seafloor without disturbing the sediment and creatures around it. In this work, computational analysis was performed on a model of a single stingray fin to determine how the motion of the fin affects the water around it, and how the water affects the fin in turn. The results were analyzed both in terms of the wake behind the fin and in terms of how much power was required to make the fin move in a particular way. The speed of the fin motion was found to have the strongest effect in controlling swimming speed, although the lateral motion of the fin also helped with accelerating faster. Additionally, the potential for a robotic stingray fin to harness power from the water around it was examined. Based on results from simulations of the fin, a mathematical model was formulated to relate energy harvesting with the flow speed past the fin. This model was used to determine how worthwhile it was to use energy harvesting. Analysis of the model showed that harvesting energy from the water was quite efficient, and would likely be a worthwhile investment for an exploration mission.
Abdelkefi, Abdessattar. "Global Nonlinear Analysis of Piezoelectric Energy Harvesting from Ambient and Aeroelastic Vibrations". Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/28761.
Texto completoPh. D.
Forester, Sean M. "Energy harvesting for self-powered, ultra-low power microsystems with a focus on vibration-based electromechanical conversion". Thesis, Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Sep/09Sep%5FForester.pdf.
Texto completoThesis Advisor(s): Singh, Gurminder ; Gibson, John. "September 2009." Description based on title screen as viewed on November 6, 2009. Author(s) subject terms: Microelectromechanical systems, photovoltaic, piezoelectric, thermocouple, power harvesting, energy scavenging, thermoelectric. Includes bibliographical references (p. 59-65). Also available in print.
Maiorca, Felice. "Innovative Electromechanical Transduction Mechanisms for Piezoelectric Energy harvesting from Vibration: Toward Micro and Nano Electro-Mechanical Systems". Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/3949.
Texto completoHinchet, Ronan. "Electromechanical study of semiconductor piezoelectric nanowires. Application to mechanical sensors and energy harvesters". Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT013/document.
Texto completoSmart systems are the combined result of different advances in microelectronics leading to an increase in computing power, lower energy consumption, the addition of new features, means of communication and especially its integration and application into our daily lives. The evolution of the field of smart systems is promising, and the expectations are high in many fields: Industry, transport, infrastructure and environment monitoring as well as housing, consumer electronics, health care services but also defense and space applications. Nowadays, the integration of more and more functions in smart systems is leading to a looming energy issue where the autonomy of such smart systems is beginning to be the main issue. Therefore there is a growing need for autonomous sensors and power sources. Developing energy harvesters and self-powered sensors is one way to address this energy issue. Among the technologies studied, piezoelectricity has the advantage to be compatible with the MEMS industry, it generates high voltages and it has a high direct coupling between the mechanic and electric physics. Among the piezoelectric materials, semiconductor piezoelectric nanowires (NWs) could be a promising option as they exhibit improved piezoelectric properties and higher maximum flexion.Among the different piezoelectric NWs, ZnO and GaN NWs are the most studied, their piezoelectric properties are more than doubled at the nanoscale. They have the advantage of being IC compatible and reasonably synthesizable by top-down and bottom-up approaches. Especially we studied the hydrothermal growth of ZnO NWs. In order to use them we studied the behavior of ZnO NWs. We performed analytical study and FEM simulations of a ZnO NW under bending. This study explains the piezoelectric potential distribution as a function of the force and is used to extract the scaling rules. We have also developed mechanical AFM characterization of the young modulus of ZnO and GaN NWs. Following we perform piezoelectric AFM characterization of these NWs, verifying the behavior under bending stresses. Once physics understood, we discuss limitation of our piezoelectric NWs models and a more realistic model is developed, closer to the experimental configurations. Using this model we evaluated the use of ZnO NW for force and displacement sensors by measuring the potential generated, and from experiments, the use of GaN NW for force sensor by measuring the current through the NW. But energy harvesting is also necessary to address the energy issue and we deeper investigate this solution. To fully understand the problematic we study the state of the art of nanogenerator (NG) and their potential architectures. We analyze their advantages and disadvantages in order to define a reference NG structure. After analytical study of this structure giving the basis for a deeper understanding of its operation and challenges, FEM simulations are used to define optimization routes for a NG working in compression or in bending. The fabrication of prototypes and theirs preliminary characterization is finally presented
CIRCOSTA, SALVATORE. "Rotary electromechanical shock absorbers for automotive and motorcycle applications". Doctoral thesis, Politecnico di Torino, 2022. https://hdl.handle.net/11583/2971316.
Texto completoCalavalle, Francesco. "Electrospun polymer nanofibers for electromechanical transduction investigated by scanning probe microscopy". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13504/.
Texto completoSmilek, Jan. "Energy Harvesting Power Supply for MEMS Applications". Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-386765.
Texto completoMANCA, NICOLO'. "Functional modelling and prototyping of electronic integrated kinetic energy harvesters". Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2675157.
Texto completoEddiai, Adil. "Caractérisation et modélisation des polymères électro-actifs : Application à la récupération d’énergie". Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0029/document.
Texto completoThe concept of energy harvesting generally relates to the process of using ambient energy, which is converted, primarily (but not exclusively) into electrical energy in order to power small and autonomous electronic devices. Recent trends in both industrial and research fields have focused on electro-active polymers for electromechanical energy conversion. This interest is explained by many advantages such as high productivity, high flexibility, and processability. The purpose of this research work is to explore the potential of electro-active polymers for application of mechanical energy harvesting. At first, a synthesis of the composite based on polyurethane (PU) and P (VDF-TrFE-CFE) was performed, followed by electrical and mechanical characterization of these polymers and composites in order to evaluate their intrinsic parameters. The second part of this thesis concerns electromechanical characterization of these polymers. An electromechanical analytic modeling is detailed in order to determine the physical behavior of electrostrictive polymers and the variations of intrinsic parameters. This modeling is validated by a series of tests using a test bench. The last part of this work consists to evaluate the electromechanical performance of electrostrictive polymers for the mechanical energy harvesting. Two new techniques are tested in order to maximize the density of energy recovered. As well as a comparison against those classic has been performed. Excellent potential of these techniques for energy harvesting has been demonstrated. The second point is about the study of the electromechanical conversion efficiency for scavenging mechanical energy using spectral analysis FFT. It was shown that this method allows predicting the energy efficiency of our polymers, in accordance with the results predicted by the model. The last point focuses on improving the efficiency of electromechanical conversion by using cellular polypropylene electrets to ensure better energy efficiency
Ahmed-Seddik, Bouhadjar. "Systèmes de récupération d'énergie vibratoire large bande". Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENT057/document.
Texto completoThe work of this thesis is focused on the mechanical energy harvesting. This technology is generally based on the use of resonant transducers. Such systems work efficiently when their resonant frequency is equal to the vibration one. Otherwise, the output power from the harvester drops dramatically. Hence, it's necessary to ensure a continuous control of the resonant frequency of the harvester in order to avoid a possible shift between the resonant frequency and the vibration one, and doing this over the frequency spectrum covered by the vibration source. The main goal of this thesis is to develop new efficient solutions able to control in real time and tune the resonant frequency, these solutions should be low power consumption. During this thesis, three solutions have been developed: 1) adjustement of the resonant frequency by applying an electric field on the piezoelectric material; 2) adjustement of the resonant by adapting the electrical load; 3) the amplification of the structure relative displacement using a rebound technique. Modelling and optimization of both the frequency adjustment techniques and the mechanical-to-electrical conversion were performed. Three structures have been developed, tested and used to validate the three approaches. Finally, a very low power consumption electronic has been developed for a real time control of the resonant frequency, by regarding the vibration frequency, and also to optimize the extracted electrical energy from the harvester by maintaining an optimum quality factor
Esu, Ozak O. "Vibration-based condition monitoring of wind turbine blades". Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/21679.
Texto completoSijková, Simona. "Návrh testovacího přípravku piezoelektrických vlastností PVDF vrstvy". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417737.
Texto completoBelhora, Fouad. "Couplage multiphysique à l’aide d’électret application à la récupération d’énergie". Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0141/document.
Texto completoIn the last decades, direct energy conversion devices for medium and low grades waste heat have received significant attention due to the necessity to develop more energy efficient engineering systems. A great deal of research has in recent years been carried out on harvesting energy using piezoelectric, electrostatic, electromagnetic , and thermoelectric ,transduction, with the aim of harvesting enough energy to enable data transmission. For this purpose, piezoelectric elements have been extensively used in the past; however they present high rigidity and limited mechanical strain abilities as well as delicate manufacturing process for complex shapes, making them unsuitable in many applications. Thus, recent trends in both industrial and research fields have focused on electrostrictive polymers for electromechanical energy conversion. This interest is explained by many advantages such as high productivity, flexibility, and processability. Hence, electrostrictive polymer films are much more suitable for energy harvesting devices requiring high flexibilities, such as systems in smart textiles and mobile or autonomous devices. Electrostrictive polymers can also be obtained in many different shapes and over large surfaces. . In the last years, electrostrictive polymers have been investigated as electroactive materials for energy harvesting. However for scavenging energy a static field is necessary, since this material is isotope, there is no permanent polarization compare to piezoelectric material. A solution for avoid this problem; concern the hybridization of electrostrictive polymer with electret. Finally, the implementation of electrostrictive materials is much simpler for small-scale systems (MEMS). Hence, several studies have analyzed the energy conversion performance of electrostrictive polymers, both in terms of actuation and energy harvesting
Maaroufi, Seifeddine. "Conception et réalisation d’un banc pour l’étude de fiabilité des micros dispositifs piézoélectriques de récupération d’énergie dédiés aux implants cardiaques". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS187/document.
Texto completoWithin the framework of this PhD we present the design and realization of a bench dedicated to the study of the reliability of piezoelectric structures and more precisely micro-devices of energy harvesting for the new generation of active and autonomous medical implants. The structures studied are in the form of a free-clamped piezoelectric bimorph having a seismic mass at their tip. A good understanding of the aging of the materials and of the mechanical and electrical failure modes is essential for this type of system where the life of the patient implanted by this device is directly involved. To study the reliability and durability of the active part of the harvester, we propose to establish a new accelerated aging methodology via a dedicated test bench where the environment and stimuli can be controlled accurately over a large period of time. An electromechanical characterization of the structures is periodically carried out by the extraction of a series of indicators (blocking force, stiffness, tension in harmonic regime) within the bench throughout the aging process. Therefore it is possible to identify the different potential failure modes and to study their impact on the proper functioning of the system
Vidal, João Vasco Silvestre. "Magnetoelectric effect in composites based on single crystalline piezoelectrics". Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/18005.
Texto completoEste trabalho expõe um estudo teórico e experimental das propriedades anisotrópicas magnetoelétricas (ME) em diferentes compósitos contendo monocristais piezoelétricos (PE), maioritariamente sem chumbo na sua composição, com vista a diversas aplicações multifuncionais. Uma descrição linear do efeito ME em termos de campos elétricos, magnéticos e elásticos e constantes materiais é apresentada. Um modelo fenomenológico quasi-estático é usado para ilustrar a relação entre as constantes materiais, sua anisotropia e os coeficientes MEs transversais de tensão e carga. Subsequentemente, este modelo é empregue para estimar o máximo coeficiente ME direto de tensão expectável numa série de compósitos tri-camadas de Metglas/Piezocristal/Metglas em função da orientação do cristal PE. Demonstra-se assim como os efeitos MEs são fortemente dependentes da orientação cristalina, o que suporta a possibilidade de se gerarem coeficientes MEs de tensão elevados em compósitos contendo monocristais PEs sem chumbo como o niobato de lítio (LiNbO3; LNO), tantalato de lítio (LiTaO3), ortofosfato de gálio (GaPO4; GPO), quartzo (SiO2), langatato (La3Ga5.5Ta0.5O14) e langasite (La3Ga5SiO14) através da otimização da orientação cristalina. Uma técnica experimental dinâmica de lock-in para a medição da impedância e efeito ME direto é exposta. O formalismo descritivo desta técnica, assim como um arranjo experimental desenvolvido para o efeito são apresentados. O esquema e características deste, assim como diferentes formas de reduzir o ruído e a indesejável indução mútua são exploradas. Um estudo comparativo do efeito ME direto em compósitos tri-camadas de Metglas e monocristais de LNO e PMN-PT conectados de forma simples é exposto. Embora o PMN-PT possua piezocoeficientes de carga muito superiores aos do LNO, o coeficiente ME direto de tensão demonstrou-se comparável entre ambos os compósitos devido a uma muito menor permitividade dielétrica do LNO. Cálculos teóricos indicam aínda que as propriedades MEs poderão ser significativamente melhoradas (até 500 V/(cm.Oe)) através da otimização do ângulo de corte do LNO, espessura relativa entre camadas ferroelétrica/ferromagnética e uma melhor colagem entre o Metglas e o LNO. Vantagens da utilização do material ferroelétrico LNO em compósitos MEs são discutidas. Num estudo subsequente, as propriedades dinâmicas anisotrópicas de impedância e MEs em compósitos tri-camadas de Metglas e monocristais PEs sem chumbo de LNO e GPO são exploradas. Medições foram realizadas em função do corte de cristal, magnitude e orientação do campo magnético de polarização e frequência do campo de modulação. Coeficientes MEs altamente intensos em certos modos de ressonância são explorados, e a sua relação com as propriedades materiais dos cristais e geometria dos compósitos é investigada. Um coeficiente ME de até 249 V/(cm.Oe) foi aqui observado num compósito com um cristal de LNO com corte 41ºY a 323.1 kHz. Mostramos assim que compósitos multicamadas contendo cristais sem chumbo de LNO e GPO podem exibir efeitos MEs anisotrópicos relativamente elevados. Demonstramos também que o controlo da orientação dos cristais PEs pode em princípio ser usado na obtenção de propriedades MEs anisotrópicas desejáveis para qualquer aplicação. Características únicas como elevada estabilidade química, piezoeletricidade linear e robusteza térmica abrem verdadeiras perspetivas para a utilização de compósitos baseados no LNO e GPO em diversas aplicações. Eventualmente, compósitos bi-camadas contendo lâminas PEs com bidomínios de LNO com corte 127ºY foram estudados tanto teoricamente como experimentalmente. Estas lâminas de LNO possuem uma estrutura de bidomínios com vetores de polarização espontânea opostos ao longo da direção da sua espessura (i.e. uma estrutura de macrodomínios ferroelétricos “head-to-head” ou “tail-to-tail”) Medições de impedância, efeito ME e densidade de ruido magnético equivalente foram realizadas nos compósitos operando sob condições quasi-estáticas e de ressonância. Coeficientes MEs de até 578 V/(cm.Oe) foram obtidos a ca. 30 kHz sob ressonâncias de dobramento usando cristais PEs com 0.5 mm de espessura. Medições de densidade de ruído magnético equivalente demosntraram valores de até 153 pT/Hz1/2 a 1 kHz (modo quasi-estático) e 524 fT/Hz1/2 sob condições de ressonância. É de esperar que uma otimização adicional das técnicas de fabrico, geometria dos compósitos e circuitos de detenção possa permitir reduzir estes valores até pelo menos 10 pT/Hz1/2 e 250 fT/Hz1/2, respetivamente, e a frequência de ressonância em pelo menos duas ordens de grandeza. Estes sistemas poderão assim no futuro ser usados em sensores vetoriais de campo magnético simples e sensíveis, passivos e estáveis e operáveis a elevadas temperaturas.
This work presents a theoretical and experimental study of the anisotropic magnetoelectric (ME) properties of differently structured composites featuring piezoelectric (PE) single-crystals, mainly lead-free, for diverse multifunctional applications. A linear description of the ME effects in terms of electric, magnetic and elastic fields and material constants is offered. An averaging quasi-static phenomenological model is used to illustrate the relation between the material constants, their anisotropy and the transversal direct ME voltage and charge coefficients. Subsequently, the aforementioned model is employed in the calculation of the maximum expected direct ME voltage coefficient for a series of tri-layered Metglas/Piezocrystal/Metglas composites as a function of the PE crystal orientation. The ME effects are shown to be strongly dependent on the crystal orientation, which supports the possibility of inducing large ME voltage coefficients in composites comprising lead-free PE single crystals such as lithium niobate (LiNbO3; LNO), lithium tantalate LiTaO3, gallium phosphate (GaPO4; GPO), quartz (SiO2), langatate (La3Ga5.5Ta0.5O14) and langasite (La3Ga5SiO14) through the optimization of the crystal orientation. An experimental dynamic lock-in technique for the measurement of the impedance and direct ME effect is presented. The formalism describing this technique and an implemented custom-made setup are introduced. The scheme and characteristics of the latter as well as ways to reduce the noise and the undesirable mutual induction are explored. A comparative study of the direct ME effect in simply bonded tri-layered laminates of Metglas and LNO and PMN-PT crystals is exposed. Though PMN-PT has much larger charge piezocoefficients than LNO, the direct magnetoelectric voltage coefficient is found to be comparable in both trilayers due to the much lower dielectric permittivity of LNO. Calculations show that the ME properties can be significantly improved (up to 500 V/(cm·Oe)) via an optimization of the cut angle of LNO, relative thickness ratio of the ferroelectric/ferromagnetic layers and a better bonding between Metglas and LNO. Advantages of using the LNO ferroelectric in ME composites are discussed. In a subsequent study, the dynamic impedance and ME anisotropic properties of tri-layered composites of Metglas and single-crystalline lead-free PE of LNO and GPO are explored. Measurements have been performed as a function of the crystal-cut, magnitude and orientation of the magnetic bias field and frequency of the modulated field. Greatly enhanced ME coefficients in certain resonance modes are explored, and their relation to the material properties of the crystals and the geometry of the composites is investigated. The largest ME coefficient of up to 249 V/(cm·Oe) was observed for a composite with a 41ºY-cut LNO crystal at 323.1 kHz. We thus show that multilayers comprising lead-free LNO and GPO crystals can exhibit relatively large anisotropic ME effects. We also demonstrate that the control of the PE crystal’s orientation can in principle be used to obtain almost any desired quasi-static and resonant anisotropic ME properties for any given application. Such unique features as chemical stability, linear piezoelectricity and thermal robustness open up a real perspective of using lead-free LNO and GPO based ME tri-layers in various applications. Eventually, bi-layered composites comprising PE bidomain plates of 127ºY-cut LNO were studied both theoretically and experimentally. The LNO plates possessed an engineered bidomain structure with opposite spontaneous polarization vectors along the thickness direction (i.e. a “head-to-head” or “tail-to-tail” ferroelectric macrodomain structure). Impedance, ME effect and equivalent magnetic noise density measurements have been performed on the composites operating under quasi-static and resonant conditions. ME coefficients of up to 578 V/(cm·Oe) were obtained at ca. 30 kHz at the bending resonance using 0.5 mm thick piezoelectric crystals. Equivalent magnetic noise density measurements yielded values down to 153 pT/Hz1/2 at 1 kHz (quasi-static mode) and 524 fT/Hz1/2 under resonant conditions. A further optimization of the fabrication techniques, laminate geometry and detection circuit is expected to allow reducing these values down to at least 10 pT/Hz1/2 and 250 fT/Hz1/2, respectively, and the resonance frequency by at least two orders of magnitude. Such systems may in future thus find use in simple and sensitive, passive and stable, low-frequency and high-temperature vector magnetic field sensors.
Tao, Ran. "Piezoelectric generators based on semiconducting nanowires : simulation and experiments". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAT094/document.
Texto completoEnergy autonomy in small sensors networks is one of the key quality parameter for end-users. It’s even critical when addressing applications in structures health monitoring (avionics, machines, building…), or in medical or environmental monitoring applications. Piezoelectric materials make it possible to exploit the otherwise wasted mechanical energy which is abundant in our environment (e. g. from vibrations, deformations related to movements or air fluxes). Thus, they can contribute to the energy autonomy of those small sensors. In the form of nanowires (NWs), piezoelectric materials offer a high sensibility allowing very small mechanical deformations to be exploited. They are also easy to integrate, even on flexible substrates.In this PhD thesis, we studied the potential of semiconducting piezoelectric NWs, of ZnO or III-V compounds, for the conversion from mechanical to electrical energy. An increasing number of publications have recently bloomed about these nanostructures and promising nanogenerators (NGs) have been reported. However, many questions are still open with, for instance, contradictions that remain between theoretical predictions and experimental observations.Our objective is to better understand the physical mechanisms which rule the piezoelectric response of semiconducting NWs and of the associated NGs. The experimental work was based on the fabrication of VING (Vertical Integrated Nano Generators) devices and their characterization. An electromechanical characterization set-up was built to evaluate the performance and thermal effects of the fabricated NGs under controlled compressive forces. Atomic Force Microscopy (AFM) was also used to evaluate the Young modulus and the effective piezoelectric coefficients of GaN, GaAs and ZnO NWs, as well as of ZnO-based core/shell NWs. Among them, ZnO NWs were grown using chemical bath deposition over rigid (Si) or flexible (stainless steel) substrates and further integrated to build VING piezoelectric generators. The VING design was based on simulations which neglected the effect of free carriers, as done in most publications to date. This theoretical work was further improved by considering the complete coupling between mechanical, piezoelectric and semiconducting effects, including free carriers. By taking into account the surface Fermi level pinning, we were able to reconcile theoretical and experimental observations. In particular, we propose an explanation to the fact that size effects are experimentally observed for NWs with diameters 10 times higher than expected from ab-initio simulations, or the fact that VING response is non-symmetrical according to whether the substrate on which it is integrated is actuated with a convex or concave bending
Wang, Liuqing. "Etude et développement de nouveaux matériaux et structures électroactifs pour la récupération d'énergie". Thesis, Lyon, INSA, 2014. http://www.theses.fr/2014ISAL0083/document.
Texto completoThis thesis has been devoted to electrostatic mechanical energy harvesting based on capacitors inspired by fractal geometry, to mechanical energy harvesting based on beams with electrostrictive polymers, and to thermal energy harvesting based on ferromagnetic materials. For electrostatic energy harvesting without electrets, interdigitated capacitors are usually applied as in-plane overlap varying and in-plane gap closing electrostatic generators. In consideration of the limit of aspect ratio for fingers in the capacitor, we would like to improve the capacitor configuration by taking advantage of self-similarity patterns. The concept is to gradually add fingers of smaller widths between original ones to form a mountain-shape capacitor. According to the different width ranges of capacitors, they are classified as of different orders whose performances vary with the vibration amplitude. Harvested energy over one cycle for capacitors of order 1, 2 and 3 has been demonstrated by theoretical and FEM results. In application, the order of capacitor needs to be properly chosen to maximize the harvested energy. Electrostrictive polymer (polyurethane) has been utilized along with a beam to perform mechanical energy harvesting. Two models have been analyzed: clamped-free beam with a polymer film attached at the clamped end, clamped-free bimorph beam. The simple model for electrostrictive devices under flexural solicitation is set up on the base of analysis of energy conversion and it shows that the electrostrictive system can be reduced to a simple spring-mass-damper system with a quadratic dependence with the applied voltage on the mechanical side and to a current source controlled by the applied voltage with a capacitive internal impedance on the electrical side. Experiments based on the clamped-free beam with a polymer film attached to the clamped end have been carried out to evaluate the mechanical to electrical conversion. The thermal energy generator is based on a ferromagnetic material, a magnet and a coil. As the magnetic permeability of ferromagnetic materials encounters drastic variation around the Curie temperature, the concept of the generator is to take advantage of the permeability variation caused by temperature decrease to generate sharp variation in magnetic flux which induces a current in the coil. According to theoretical results, the generated current is closely related to the temperature variation and the variation velocity. Experiments have been carried out on Ni30Fe of which the Curie temperature is 55 ºC. When the temperature decreases from 20.5 ºC to -42.4 ºC, the maximum power is about 4×10^(-7)W with the load to be 2 Ω
Hsieh, Meng-Jung y 謝孟融. "A Study on Electromechanical Materials for Ship Vibration Energy Harvesting". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/a64au8.
Texto completoELAHI, HASSAN. "Piezoelectric energy harvesting by aeroelastic means". Doctoral thesis, 2020. http://hdl.handle.net/11573/1364130.
Texto completoCheng, YaLun y 鄭雅倫. "Electromechanical efficiency improvement of electrode design in series piezoceramic bimorph for energy harvesting". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/37505683755369490325.
Texto completo國立臺灣科技大學
機械工程系
104
The energy harvesting systems of piezoelectric material are investigated on the electromechanical coupling coefficient by segmented electrode in this study. The piezoceramic plate and bimorphs are used to perform the vibration characteristics by experimental measurements and finite element method (FEM). Thereafter, the dynamic characteristics and the electromechanical coupling efficiency of the piezoelectric energy harvesting system are studied by the electrode design method for single-layer piezceramic plate and for piezoelectric bimorphs in series-electrically connection. This study thoroughly analyzed vibration dynamic characteristics of piezoelectric materials by experimental measurements and numerical calculations. Several experimental techniques are used to measure the dynamic characteristics of piezoelectric materials. First, the full-filed optical technique, amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI), can measure simultaneously the resonant frequencies and mode shapes for out-of-plane and in-plane vibrations. Second, the pointwise measurement system, laser Doppler vibrometer (LDV), can obtain resonant frequencies by dynamic signal swept-sine analysis. Third, the correspondent in-plane resonant frequencies and anti-resonant frequencies are obtained by impedance analysis. The experimental results of vibration characteristics are verified with numerical calculations. After the dynamic characteristics of piezoelectric materials are analyzed in converse piezoelectric effect, the piezoelectric materials are excited by shaker to generate the electric voltage and applied on the stimulation of LED. It has excellent consistence between resonant frequencies and mode shapes on the vibration characteristics by experimental measurements and finite element numerical calculations. In this study, the Electrical Potential Gradient(EPG)and Electrical flux vector and magnitude (EFLX ) calculated by FEM is proposed to evaluate the electromechanical coupling efficiency of piezoceramic plate on the specific vibration mode. The correspondent electrode configuration, which is designed by EPG and EFLX, can produce the best electromechanical transfer both in direct and converse piezoelectric effects. Finally, the series piezoelectric bimorphs in series connection can use electrode design method to find the best electromechanical transfer efficiency of each resonant frequencies. It is concluded that the vibration characteristics of piezoelectric materials in electrode design have excellent consistence determined by experimental measurements and FEM.
Chen, Kuan-Ting y 陳冠廷. "A Study of Electromechanical Behavior of Piezoelectric Energy-Harvesting System Using Finite Element Method". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/29135551772977378470.
Texto completo國立臺灣大學
應用力學研究所
99
The research of energy harvesting from environmental resources has received increasing attention due to the decreasing supply of fossil energy. With the advances of MEMS technology and the reduction of power requirement in electronic devices, harvesting energy from vibration sources becomes achievable. This thesis studies the vibration-based piezoelectric energy harvesting based on the finite element simulation. First, the mathematical model is established using the force balance principle and the piezoelectric governing equations. Second, the finite simulation is validated by a series of experiment. The main result is the investigation of the frequency response of the piezoelectric cantilever beam endowed with the standard interface. As the current commercial finite element codes are not able to be integrated with the circuit simulators, we propose an “Equivalent Impedance” method to resolve this difficulty. The results are consistent with the theoretical predictions and agree well with experimental observations. The effect of geometry of cantilever configurations on harvested power is also studied.
CHERAGHI, BIDSORKHI HOSSEIN. "Large Scale Production of Porous and Non-Porous PVDF/GNPs Nanocomposites for Electrical and Electromechanical Applications". Doctoral thesis, 2018. http://hdl.handle.net/11573/1544693.
Texto completoKuan-WeiChen y 陳冠維. "Co-Simulation of FEM-Analytic Method-SPICE for Electromechanical Coupling Systems Applying to Optimal Design of High-Power Density Piezoelectric Energy Harvesting Modules". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/3x7g9c.
Texto completoFORTUNATO, MARCO. "Production and characterization of ZnO/Graphene devices for energy harvesting". Doctoral thesis, 2019. http://hdl.handle.net/11573/1237548.
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