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Improved one-dimensional model of piezoelectric laminates for energy harvesters including three dimensional effects
Full text linkThe application of piezoelectric composites in energy harvesters is continuously increasing even at the microscale, with the immediate corollary of a fundamental need for improved computational tools for optimization of performances at the design level. In this paper, a refined, yet simple model is proposed with the aim of providing fast and insightful solutions to the multi-physics problem of energy harvesting via piezoelectric layered structures. The main objective is to retain a simple structural model (Euler–Bernoulli beam), with the inclusion of effects connected to the actual three-dimensional shape of the device. A thorough presentation of the analytical model is presented, along with its validation by comparison with the results of fully 3D computations
A highly efficient simulation technique for piezoelectric energy harvesters
Full text linkThis paper presents a new numerical technique which is aimed at obtaining fast and accurate simulations of piezoelectric beams, used in inertial energy harvesting MEMS. The execution of numerical analyses is greatly important in order to predict the actual behaviour of MEMS device and to carry out the optimization process on the basis of Design of Experiments (DOE) techniques. In this paper, a refined, yet simple, model is proposed with reference to the multi-physics problem of piezoelectric energy harvesting by means of laminate cantilevers. The proposed model is calibrated and validated with reference to 3D finite element analyses
Multi-physics simulation of laminates with piezoelectric layers for energy harvesting
Full text linkIn this paper, a refined, yet simple, model is considered with the aim of providing fast and insightful solutions to the multi-physics problem of piezoelectric energy harvesting by means of laminate cantilevers. The main objective is to retain a simple structural model (Euler-Bernoulli beam), with the inclusion of effects connected to the actual three-dimensional shape of the device. The obtained results are validated by the comparison with 3D analysis carried out with a commercial code, and the procedure is finally applied to the case of a realistic MEMS harvester
Numerical simulations of piezoelectric effects
No full textThis paper is focused on the numerical simulation of piezoelectric effects, in view of their application in MEMS harvesters and actuators. In order to obtain a fast and accurate prediction of dynamic behavior, a simple 1-DOF model has been introduced for thin piezoelectric beams. The validation of the model has been carried out by comparison with full 3D simulations via commercial codes
Trasduttore piezoelettrico per un sistema di raccolta dell’energia e metodo per la raccolta di energia mediante un trasduttore piezoelettrico
No full textLa presente invenzione riguarda un nuovo sistema di Energy Harvesting da vibrazione con capacità di recuperare energia da movimenti a frequenze basse e variabili (come possono essere le oscillazioni di edifici e i movimenti del corpo umano). Il nuovo dispositivo presenta completa compatibilità con le tecniche standard di microlavorazione tipicamente utilizzate nell’ambito di microsistemi, detti anche dispositivi microelettromeccanici (MEMS), risultando pertanto facilmente industrializzabile. La presenza di altri materiali rispetto al silicio (piezoelettrici e magnetici) non costituisce un ostacolo per le odierne tecniche di microfabbricazione. Il progetto proposto consente di realizzare un dispositivo estremamente versatile, utilizzabile in diverse applicazioni. L’attività inventiva ha in particolare riguardato la tecnica di conversione di energia (oscillazione libera di una serie piastre a mensola stratificate con materiale piezoelettrico) e il metodo per innescare la vibrazione dei suddetti elementi (Frequency-up-Conversion tramite interazione tra magneti posti sulle travi con magneti posti su una grossa massa in movimento, la grossa massa ha lo scopo di recuperare energia cinetica convertendola, tramite un’interazione tra magneti senza che questi vengano a contatto, in energia elastica immagazzinata nelle piastre). Da un lato, l’invenzione risolve il problema di evitare contatti tra parti, cosa che renderebbe il dispositivo meno affidabile; dall’altro garantisce il recupero di energia qualunque siano le caratteristiche della vibrazione esterna. In aggiunta ci si è particolarmente concentrati sul design di un dispositivo compatibile con le tecniche di fabbricazione per microsistemi. Si è rispettato il vincolo di planarità di tale tecnologia limitando il più possibile l’ingombro fuori piano dell’oggetto. Alla data odierna nessun dispositivo proposto presenta il metodo di frequency-up-Conversion in aggiunta alla compatibilità con i processi di fabbricazione MEM
Modeling of a bridge-shaped nonlinear piezoelectric energy harvester
No full textPiezoelectric microelectromechanical systems
(MEMS) energy harvesting is an attractive technology
for harvesting small energy from ambient vibrations.
Increasing the operating frequency bandwidth of such
devices is one of the major challenges to be solved for
real-world applications. A MEMS-scale doubly clamped
nonlinear beam resonator has demonstrated very wide
bandwidth and high-power density among the energy
harvesters reported. In this paper, a first complete theoretical
discussion of nonlinear resonance-based piezoelectric
energy harvesting is provided. The sectional
behavior of the beam has been studied through the
Classical Lamination Theory (CLT) specifically modified
to introduce the piezoelectric coupling and nonlinear
Green-Lagrange strain tensor. A lumped parameter
model has been built through Rayleigh???Ritz method
and the resulting nonlinear coupled equations have
been solved in the frequency domain through the
Harmonic Balance Method (HBM). Finally, the influence
of external load resistance on the dynamic behavior has
been studied. The theoretical model shows that nonlinear
resonant harvesters have much wider power bandwidth
than that of linear resonators but their maximum power
is still bounded by the mechanical damping as is the case
for linear resonating harvester
Piezoelectric Transducer for an Energy-Harvesting System
No full textA piezoelectric transducer for energy-harvesting systems includes a substrate, a piezoelectric cantilever element, a first magnetic element, and a second magnetic element, mobile with respect to the first magnetic element. The first magnetic element is coupled to the piezoelectric cantllever element. The first magnetic element and the second magnetic element are set in such a way that, in response to relative movements between the first magnetic element and the second magnetic element through an interval of relative positions, the first magnetic element and the second magnetic element approach one another without coming into direct contact, and the interaction between the first magnetic element and the second magnetic element determines application of a force pulse on the piezoelectric cantilever element
Modelling of a bridge-shaped nonlinear piezoelectric energy harvester.
No full textPiezoelectric MicroElectroMechanical systems (MEMS) energy harvesting is an attractive technology for harvesting small magnitudes of energy from ambient vibrations. Increasing the operating frequency bandwidth of such devices is one of the major issues for real world applications. A MEMS-scale doubly clamped nonlinear beam resonator is designed and developed to demonstrate very wide bandwidth and high power density. In this paper a first complete theoretical discussion of nonlinear resonating piezoelectric energy harvesting is provided. The sectional behaviour of the beam is studied through the Classical Lamination Theory (CLT) specifically modified to introduce the piezoelectric coupling and nonlinear Green-Lagrange strain tensor. A lumped parameters model is built through Rayleigh-Ritz Method and the resulting nonlinear coupled equations are solved in the frequency domain through the Harmonic Balance Method (HBM). Finally, the influence of external load resistance on the dynamic behaviour is studied. The theoretical model shows that the power generation of nonlinear resonant harvesters is spread out on a wider bandwidth but it is theoretically bounded by the mechanical damping of the dynamic system as for linear resonating harvesters
On the application of piezolaminated composites to diaphragm muicropumps
Full text linkThis paper deals with the numerical simulation of piezolaminated microplates adopted as actuators in micropumps. The performances of piezoelectric actuation are critically assessed by means of comparisons with devices based on the electrostatic force. In order to perform accurate simulations of the micropump behavior, the theory of laminates is adopted, account taken of the piezoelectric coupling. Both static and dynamic analyses have been performed, in order to obtain information on the optimal configuration for the micropump
Numerical simulations of piezoelectric MEMS energy harvesters
No full textThe application of piezoelectric materials in MEMS
energy harvesters is continuously increasing, with the
immediate corollary of a fundamental need for improved
computational tools in order to optimize the performances
at the design level. In this paper, a refined, yet simple
model is proposed with the aim of providing fast and
insightful solutions to the multi-physics problem of
piezoelectric energy harvesting. The main objective is to
retain a simple structural model (Euler-Bernoulli beam),
with the inclusion of effects connected to the actual threedimensional
shape of the device. A thorough presentation
of the analytical model is presented, along with its
validation by comparison with the results of full 3D
computations
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