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Theoretical and Experimental Features of Nano-Crystals Rochelle Salt: Piezoelectric Resonance and Phase Transition
摘要： A new methodology based on Three-Electrode System (TES) technique was used to measure both, elastic (C44) and piezoelectric (d14) constants of Rochelle salt (RS) crystal. This technique was also used to observe the phase transitions at ?18 °C and 24 °C, manifested as an increase of the output signal at these temperatures. Mechanical wave attenuation coefficient (α) into the crystal was found. Also, first principle methodology in the framework of the density functional theory was utilized to confirm the electronic structure of Rochelle Salt. The results present high accuracy theoretical/experimental as well as a complete agreement with those known in the literature done by different methodologies.
关键词： Phase Transitions,Rochelle Salt Crystal,Piezoelectric Device,Ab Initio Simulation
更新于2025-09-23 15:22:29
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Fuzzy neural network vibration control on a piezoelectric flexible hinged plate using stereo vision detection
摘要： Vibration control on a two-connected piezoelectric flexible hinged plate is investigated, using a fuzzy neural network algorithm based on binocular vision measurement. As for vision sensing, a method to acquire vibration signals of the low frequency bending and torsional mode is investigated. To damp out the residual vibration quickly, the fuzzy neural network is applied to ensure the stability and control effect adaptively. To verify the stereo vision measurement method and the applied controller, an experimental setup of the piezoelectric flexible hinged plate with a binocular stereo vision is constructed. Experiments are conducted by using the binocular stereo vision measurement system and the adopted controller. The experimental results demonstrate the feasibility of the visual measurement method. Furthermore, the designed fuzzy neural network can attenuate the bending and torsional vibrations quickly, in comparison with proportional and derivative control, particularly for the small-level residual vibration.
关键词： Piezoelectric flexible hinged plate,binocular vision measurement,experiments,vibration control,fuzzy neural network algorithm
更新于2025-09-23 15:22:29
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Mass measurement of grasped object with tweezers employing bimorph piezoelectric actuators
摘要： This paper deals with tweezers for a mass detection during micromanipulation. It measures 52 mm×30 mm×10 mm and weighs 37 g. Each ?nger consists of a bimorph piezoelectric actuator with a stainless steel tip. One of the tweezers working as a vibrator was oscillated at its resonance frequency, and another working as a grasper opened and closed the gap between the tips of the bimorph piezoelectric actuators. The simulation model that represents the contact of two beams and a lumped mass as springs was described. The resonance frequency was increased when the tweezers grasped an object. The relationship between the mass of the object and frequency was obtained experimentally. Because the charge generated by the piezoelectric effect also affected the resonance frequency, the frequency change in the experiments was smaller than that in the simulation.
关键词： resonance frequency,mass evaluation,cantilever,Piezoelectric actuator,vibration
更新于2025-09-23 15:22:29
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PZT/PZT and PZT/BiT Composite Piezo-Sensors in Aerospace SHM Applications: Photochemical Metal Organic + Infiltration Deposition and Characterization
摘要： The composition of fine-ground lead zirconate-titanate powder Pb(Zr0.52Ti0.48)O3, suspended in PZT and bismuth titanate (BiT) solutions, is deposited on the curved surface of IN718 and IN738 nickel-based super alloy substrates up to 100 μm thickness. Photochemical metal organic and infiltration techniques are implemented to produce smooth, semi-dense, and crack-free random orientated thick piezoelectric films as piezo-sensors, free of any dopants or thickening polymers. Every single layer of the deposited films is heated at 200 °C with 10 wt.% excess PbO, irradiated by ultraviolet lamp (365 nm, 6 watt) for 10 min, pyrolyzed at 400 °C, and subsequently annealed at 700 °C for one hour. This process is repeated successively until reaching the desired thickness. Au and Pt thin films are deposited as the bottom and top electrodes using evaporation and sputtering methods, respectively. PZT/PZT and PZT/BiT composite films are then characterized and compared to similar PZT and BiT thick films deposited on the similar substrates. The effect of the composition and deposition process is also investigated on the crystalline phase development and microstructure morphology as well as the dielectric, ferroelectric, and piezoelectric properties of piezo-films. The maximum remnant polarization of Pr = 22.37 ± 0.01, 30.01 ± 0.01 μC/cm2, the permittivity of εr = 298 ± 3, 566 ± 5, and piezoelectric charge coefficient of d33 = 126, 148 m/V were measured versus the minimum coercive field of Ec = 50, 20 kV/cm for the PZT/PZT and PZT/BiT thick films, respectively. The thick film piezo-sensors are developed to be potentially used at frequency bandwidth of 1–5 MHz for rotary structural health monitoring and also in other industrial or medical applications as a transceiver.
关键词： piezoelectric sensor,structural health monitoring,PZT/BiT,composite,characterization,sol-gel PMOD deposition,infiltration,aerospace structure,PZT/PZT,thick film
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on Environment and Electrical Engineering and 2018 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe) - Palermo (2018.6.12-2018.6.15)] 2018 IEEE International Conference on Environment and Electrical Engineering and 2018 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe) - Nonlinear Multi-Scale Dynamics Modeling of a Piezoelectric Energy Harvester
摘要： Hysteretic effects play a crucial role in the behavior of devices based on piezoelectric materials. Most of the research focuses on modeling these effects for controlling the dynamic response of piezoelectric actuators. Few studies discuss how hysteresis influences power generation and performances of energy harvesters based on such active materials. In this paper, a recently developed physics-based model of a PZT crystal is employed to assess the effects of material mesoscopic variables on the macroscopic response of a piezoelectric energy harvester modeled as a SDOF system. A multi-scale approach is adopted where, at the mesoscale, crystal domain switching - the source of hysteretic behavior - is taken into account through a probabilistic thermodynamic approach. Effects of hysteretic nonlinearities on harvesting performances of the considered device are investigated by means of simulations. A comparison between predictions of two models - with and without hysteresis - is also reported.
关键词： Piezoelectric,Hysteresis,Energy harvesting,Nonlinear Multi-scale Dynamics
更新于2025-09-23 15:22:29
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Generalized optimization method for energy conversion and storage efficiency of nanoscale flexible piezoelectric energy harvesters
摘要： The energy conversion and storage efficiency was commonly ignored in experimental studies on nanoscale flexible piezoelectric energy harvesters (PEHs). In this study, we develop a generalized theoretical method to optimize the energy conversion and storage efficiencies of nanoscale flexible PEHs. The results are validated by comparisons with experimental measurements for various ambient excitations. A simple scaling law is established to reveal the intrinsic correlation between the efficiency of energy conversion/storage and various system parameters of the PEHs. For either the energy conversion or storage circuit, the output power density may be maximized by properly designing an intrinsic normalized parameter. Furthermore, we demonstrate that an independent optimization criterion is indispensable for standard storage circuits since including a storage module into the conversion circuit redefines the electromechanical behavior of the PEH system. The results may be used as guidelines for optimizing the energy conversion and storage efficiencies of nanoscale flexible PEHs that have promising applications in harvesting biomechanical energies.
关键词： Scaling law,Optimization,Nanoscale flexible piezoelectric energy harvesters,Energy conversion,Energy storage
更新于2025-09-23 15:22:29
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Love-type waves in a piezoelectric-viscoelastic bimaterial composite structure due to an impulsive point source
摘要： The analysis of wave propagation phenomenon piezoelectric-viscoelastic composites still remains an unexplored field of research. The usage of a passive polymer (Epoxy) with active piezoelectric ceramic causes viscoelasticity in the piezoelectric material which results into a piezoelectric-viscoelastic composite. The present study aims to analyze the propagation behavior of Love-type wave in an exponentially graded piezoelectric-viscoelastic material (EGPVM) stratum lying over a functionally graded piezoelectric-viscoelastic material (FGPVM) substrate due to an impulsive point source at its interfacial surface. The electro-visco-mechanical field equations are laid down for the piezoelectric-viscoelastic medium.The analytical solution procedure involves the use of suitable Green’s function and admissible boundary conditions. The established frequency equation is in complex form; of which the real expression imparts the frequency curve and imaginary expression gives the attenuation curve of Love-type wave. To depict the results numerically, two distinct piezoelectric-viscoelastic materials (Epoxy-BNKLBTand Epoxy-KNLNTSceramics) for EGPVM stratum and FGPVM substrate are taken into account.The phase velocity profile and attenuation coefficient profile of Love-type wave is portrayed graphically. Diagnostic results are simulated numerically which forefronts the effect of distinct parameters. The study manifests the impact of the material medium parameters, viz. piezoelectric constants, dielectric constants, piezoelectric loss moduli, dielectric loss moduli, exponential gradient parameter and magnifying gradient parameters on the phase velocity and attenuation coefficient of Love-type wave. For sake of validation, the obtained results are matched with the classical one, as a special case of the problem. The outcomes of the study may find its worth in better and optimum design of surface acoustic wave devices and Love wave sensors, keeping efficiency at its premium.
关键词： Piezoelectric-viscoelastic,damping equation,frequency equation,point source,Green’s function,attenuation coefficient.
更新于2025-09-23 15:22:29
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3D core-multishell piezoelectric nanogenerators
摘要： The thin film configuration presents obvious practical advantages over the 1D implementation in energy harvesting systems such as easily manufacturing and processing, and long-lasting and stable devices. However, ZnO-based piezoelectric nanogenerators (PENGs) generally rely on the exploitation of single-crystalline nanowires because of their self-orientation in the c-axis direction and ability to accommodate long deformations resulting in high piezoelectric performance. Herein, we show an innovative approach to produce PENGs by combining polycrystalline ZnO layers fabricated at room temperature by plasma-assisted deposition with supported small-molecule organic nanowires (ONWs) acting as 1D scaffolds. Such hybrid nanostructures present convoluted core-shell morphology, formed by a single-crystalline organic nanowire conformally surrounded by a poly-crystalline ZnO shell and combine the organic core mechanical properties with the ZnO layer piezoelectric response. In a step forward towards the integration of multiple functions within a single wire, we have also developed ONW-Au-ZnO nanoarchitectures including a gold shell acting as inner electrode achieving output piezo-voltages up to 170 mV. The synergistic combination of functionalities in the ONW-Au-ZnO devices promotes an enhanced performance generating piezo-currents one order of magnitude larger than the ONW-ZnO nanowires and superior to the thin film nanogenerators for equivalent and higher thicknesses.
关键词： piezoelectric nanogenerators,organic nanowires,ZnO,small-molecules,plasma deposition,core-shell nanowires
更新于2025-09-23 15:22:29
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Composite modeling and parameter identification of broad bandwidth hysteretic dynamics in piezoelectric fast steering platform
摘要： Over a broadband range of frequencies, it is difficult to develop precise model of piezoelectric fast steering platforms (FSPs) due to the complex hysteretic and dynamic behaviors. This paper thus presents one approach of composite modeling and parameter identification by employing a composite hysteretic model. The proposed composite model consists of the Bouc-Wen hysteresis, electro-mechanical dynamics, creep dynamics and the high frequency mirror dynamics. Physical meanings can be found in the linear component which is beneficial to controller design and other further developments using the proposed model. A step-by-step approach is proposed to identify the composite hysteretic model. Finally, the FSP experiment is provided to validate the effectiveness of the proposed modeling and parameter identification approaches.
关键词： Electro-optical system,Creep effect,Hysteretic dynamics,Fast steering platform,Electro-mechanical dynamics,Piezoelectric actuator
更新于2025-09-23 15:22:29
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Topology optimization of flextensional piezoelectric actuators with active control law
摘要： This work deals with the concept of Topology Optimization Method (TOM) applied to the design of a flextensional piezoelectric actuator (FPEA) targeting vibration attenuation of its dynamic response. On these actuators the piezoceramic shape is usually fixed and it is more advantageous to optimize the host structure topology. The flextensional actuator is formed by two piezo-ceramic layers that act as a sensor and an actuator coupled with a constant gain active velocity feedback control law (AVFC). The optimization procedure is fully described and implemented, with no simplification for the piezo-ceramic AVFC introduced to the model acts by modifying the damping matrix according to the measurements of the state variables of the system in time-domain. The dynamic equation analyzed throughout the response for the rectangular four-noded finite element (FE) analysis is obtained by the Newmark’s time-integration method, which is applied to the physical equation and to the adjoint equation needed for the sensitivity analysis. A gradient-based optimization method is applied to minimize the response signal energy of the FPEA under a transient mechanical load. Results are obtained for different control gain values to evaluate their influence on the final topology. The optimized host structure material topology for the nc-nodes model is compared with the collapsed nodes (c-nodes) model. In addition, the nc-nodes model is useful to future developments that intends to provide an external circuit to this FPEA structure aiming to intensify the AVFC damping effect.
关键词： Topology Optimization Method,Time domain transient analysis,Flextensional Piezoactuator,Active control law,Non-collapsed piezoelectric nodes
更新于2025-09-23 15:22:29