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Yang, Xiaomei, i 楊笑梅. "Computational models for piezoelectrics and piezoelectric laminates". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31246217.
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Flynn, Anita M. "Piezoelectric Ultrasonic Micromotors". Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/7086.
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This report describes development of micro-fabricated piezoelectric ultrasonic motors and bulk-ceramic piezoelectric ultrasonic motors. Ultrasonic motors offer the advantage of low speed, high torque operation without the need for gears. They can be made compact and lightweight and provide a holding torque in the absence of applied power, due to the traveling wave frictional coupling mechanism between the rotor and the stator. This report covers modeling, simulation, fabrication and testing of ultrasonic motors. Design of experiments methods were also utilized to find optimal motor parameters. A suite of 8 mm diameter x 3 mm tall motors were machined for these studies and maximum stall torques as large as 10^(- 3) Nm, maximum no-load speeds of 1710 rpm and peak power outputs of 27 mW were realized. Aditionally, this report describes the implementation of a microfabricated ultrasonic motor using thin-film lead zirconate titanate. In a joint project with the Pennsylvania State University Materials Research Laboratory and MIT Lincoln Laboratory, 2 mm and 5 mm diameter stator structures were fabricated on 1 micron thick silicon nitride membranes. Small glass lenses placed down on top spun at 100-300 rpm with 4 V excitation at 90 kHz. The large power densities and stall torques of these piezoelectric ultrasonic motors offer tremendous promis for integrated machines: complete intelligent, electro-mechanical autonomous systems mass-produced in a single fabrication process.
3
Bruna, Magali. "Piezoelectric ceramic devices". Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615866.
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Leinvuo, J. "Flextensional piezoelectric motors". Thesis, Cranfield University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409514.
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Boestad, Albin, i Fabian Rudberg. "Piezoelectric Guitar Tuner". Thesis, KTH, Mekatronik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-296320.
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This bachelor thesis in Mechatronics account for the process of constructing an automatic guitar tuner by means of a piezo-electric sensor, a stepper motor and Arduinobased control. The E4 - string on an acoustic guitar was used as a proxy for tuning any other possible guitar string. The accuracy and tuning-speed of the construction was examined through physical experimentation. Accuracy was measured in terms of the average distance from a piezo calibrated frequency value. The tuning-speed was appraisedby counting the number of times a guitar string had to be plucked before the motor stopped within an acceptable tuning interval. The automatic guitar tuner were able to reliably get the E4 - string in tune by plucking it once within an interval of ±2 Hz and +3.8 cents and −5.1 cents from the theoretical value. The average error was −3.4 cents from the targeted value.I följande kandidatexamensarbete kontrueras en automatisk gitarrstämmare med hjälp av en piezosensor, en stegmotor och en Arduino-mikrokontroller. E4-strängen på en akustisk gitarr användes som substitut för hur stämningsproceduren skulle kunna fungera för vilken annan gitarrsträng som helst. Noggrannheten samt stämningshastigheten undersöktes genom experiment. Genomsnittet av frekvensskillnaderna mellan de piezo-kalibrerade avläsningsvärdena och E4-strängens värden definierade måttet på noggrannhet. Hastigheten på strängstämningen beräknades i form av hur många gånger en sträng behövdes slås an innan strängen var inom ett godkänt intervall. Den automatiska gitarrstämmaren visade sig pålitiligt kunna stämma E4-strängen på ett försök inom ett noggrannhetsintervall på ±2Hz från det teoretiska värdet. Stämmaren kunde stämma inom +3.4 cents och−5.1 cents samt var var i genomsnitt −3.4 cents i från det teoretiska värdet.
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Barham, Oliver M. "Microfabricated Bulk Piezoelectric Transformers". Thesis, University of Maryland, College Park, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10615552.
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Piezoelectric voltage transformers (PTs) can be used to transform an input voltage into a different, required output voltage needed in electronic and electro- mechanical systems, among other varied uses. On the macro scale, they have been commercialized in electronics powering consumer laptop liquid crystal displays, and compete with an older, more prevalent technology, inductive electromagnetic volt- age transformers (EMTs). The present work investigates PTs on smaller size scales that are currently in the academic research sphere, with an eye towards applications including micro-robotics and other small-scale electronic and electromechanical sys- tems. PTs and EMTs are compared on the basis of power and energy density, with PTs trending towards higher values of power and energy density, comparatively, indicating their suitability for small-scale systems. Among PT topologies, bulk disc-type PTs, operating in their fundamental radial extension mode, and free-free beam PTs, operating in their fundamental length extensional mode, are good can- didates for microfabrication and are considered here. Analytical modeling based on the Extended Hamilton Method is used to predict device performance and integrate mechanical tethering as a boundary condition. This model differs from previous PT models in that the electric enthalpy is used to derive constituent equations of motion with Hamilton’s Method, and therefore this approach is also more generally applica- ble to other piezoelectric systems outside of the present work. Prototype devices are microfabricated using a two mask process consisting of traditional photolithography combined with micropowder blasting, and are tested with various output electri- cal loads. 4mm diameter tethered disc PTs on the order of .002cm
3 , two orders smaller than the bulk PT literature, had the followingperformance: a prototype with electrode area ratio (input area / output area) = 1 had peak gain of 2.3 (± 0.1), efficiency of 33 (± 0.1)% and output power density of 51.3 (± 4.0)W cm
-3 (for output power of80 (± 6)mW) at 1M? load, for an input voltage range of 3V-6V (± one standard deviation). The gain results are similar to those of several much larger bulk devices in the literature, but the efficiencies of the present devices are lower. Rectangular topology, free-free beam devices were also microfabricated across 3 or- ders of scale by volume, with the smallest device on the order of .00002cm
3 . These devices exhibited higher quality factorsand efficiencies, in some cases, compared to circular devices, but lower peak gain (by roughly 1/2 ). Limitations of the microfab- rication process are determined, and future work is proposed. Overall, the devices fabricated in the present work show promise for integration into small-scale engi- neered systems, but improvements can be made in efficiency, and potentially voltage gain, depending on the application
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Zhu, Zangyuan. "Lead-free piezoelectric ceramics". Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.581971.
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Legislation arising from health and environmental concerns has intensified research into finding suitable alternatives to lead-based electroceramics. Lead zirconate titanate (PZT) has been developed over several decades to become the market-leading piezoelectric ceramic. Lead-free solid solutions based on sodium potassium niobate, Na0.5K0.5NbO3 (NKN), show promising dielectric and piezoelectric properties. 1-2 The related (l-x)( Na0.5K0.5NbO3)-xBiScO3 binary system (NKN-BS) has been reported to exhibit maximum d33 values of 200 pCIN at 2 mol% BS.3 Similarly, an optimal d33 value has been reported for the binary NKN-LT system at 5-6 mol% LiTa03.4 In this work, a series of compositions along the compositional join in the ternary NKN-LT-BS system, extending from 0. Na0.5K0.5NbO3 -0.02BiScO3 toward LiTa03 have been prepared and characterized. A 0.98[0.98NKN - 0.02(LiTaO3)] - 0.02[BiScO3] (NKN- 2L T -2BS) composition showed enhanced piezoelectric properties, relative to similar compositions, with d33 values of 215 pCIN. This can be attributed to a phase content of mixed orthorhombic (or monoclinic) and tetragonal phases at ambient temperatures. Variable temperature X-ray diffraction (XRD), and dielectric measurements as a function of temperature, indicated phase transitions (on heating) from an orthorhombic (or monoclinic) crystal system to tetragonal and then cubic crystal systems at ~25°C and ~370°C respectively. Different types of dielectric behaviour were observed on increasing the LT content. A NKN-5%LT-2%BS composition exhibited twin dielectric peaks at high temperatures (~370°C and ~470°C), along with broad X-ray diffraction peaks and a fine grain size, < 0.5 μm. The twin dielectric peaks suggest that chemical inhomogeneities may have been present; this was examined using transmission electron microscopy (TEM) with energy dispersive X-ray analysis (EDX). Elemental segregation was observed within individual grains, such that a core-shell grain structure was evident. The twin high temperature dielectric peaks are attributed to the separate response from the core and shell regions, each of which have a characteristic Curie temperature range. Subsequently, a series of other compositions were prepared in the wider Na0.5K0.5NbO3 - LiTaO3-BiScO3 ternary system. Considering the combined data from XRD, dielectric measurements, SEM, TEM and piezoelectric properties for a wide range of compositions within the NKN-rich region of the NKN-LT-BS system, materials may be grouped into three categories, exhibiting the following defining characteristics. Type I: single, sharp dielectric Curie peak (~ 370°C); single phase by XRD; large grain size (5-10μm); chemically uniform by TEM-EDX. Type II: broad, single dielectric peak (~ 350°C); single phase by XRD; large grain size; no obvious chemical segregation. Type Ila: twin, broad dielectric peak(s) (~ 370°C and ~ 470°C); broad XRD peaks; small grain size (~ O.5μm); chemical segregation (core-shell structure) identified by TEM-EDX. Reasons for the properties of these three classes of material are discussed; comparisons are drawn with other lead-free dielectrics and piezoelectrics; finally, the potential of the materials in future device applications are considered.
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De, Poumeyrol Benjamin. "Characterization of piezoelectric paint". Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273485.
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Hack, Thorsten. "Stick-slip piezoelectric actuators". Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624403.
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Lai, Ming-Liang. "Developing piezoelectric biosensing methods". Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6109/.
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Biosensors are often used to detect biochemical species either in the body or from collected samples with high sensitivity and specificity. Those based on piezoelectric sensing methods employ mechanically induced changes to generate an electrical response. Reliable collection and processing of these signals is an important aspect in the design of these systems. To generate the electrical response, specific recognition layers are arranged on piezoelectric substrates in such a way that they interact with target species and so change the properties of the device surface (e.g. the mass or mechanical strain). These changes generate a change in the electrical signal output allowing the device to be used as a biosensor. The characteristics of piezoelectric biosensors are that they are competitively priced, inherently rugged, very sensitive, and intrinsically reliable. In this study, a compound label-free biosensor was developed. This sensor consists of two elements: a Love wave sensor and an electrochemical impedance sensor. The novelty of this device is that it can work in both dry and wet measurement conditions. Whilst the Love wave sensor aspect of the device is sensitive to the mass of adsorbed analytes under both dry and wet conditions with high sensitivity, the sensitivity coefficients in these two conditions may be different due to the different (mechanical) strengths of interaction between the adsorbed analyte and the substrate. The impedance sensor element of the device however is less sensitive to the mechanical strength of the bond between the analyte and the sensing surface and so can be used for in-situ calibration of the number of molecules bound to the sensing surface (with either a strong or weak link): conventional Love wave sensors are not sensitive to material loosely bound to the surface. Thus, a combination of results from these two sensors can provide more information about the analyte and the accuracy of the Love wave sensor measurements in a liquid environment. The device functions with label-free molecules and so special reagents are not needed when carrying out measurements. In addition, the fabrication of the device is not too complicated and it is easy to miniaturise. This may make the system suitable for point-of-care diagnostics and bio-material detection. The substrate used in these sensors is 64°Y–X lithium niobate (LiNbO3) which is a kind of piezoelectric material. On the substrate, there is a pair of interdigital transducers (IDTs) which are composed of 100 Ti/Au split-finger pairs with a periodicity (λ) of 40μm. The acoustic path length, between both IDTs, is 200λ and the aperture between the IDTs is 100λ. On top of the substrate and IDTs, there is a PMMA guiding layer with an optimised thickness ranging from 1000 nm to 1300 nm. In addition, a gold layer with thickness 100 nm is deposited on the guiding layer to act as the electrodes for the electrochemical impedance sensor. The biosensor in this study has been used to measure Protein A, IgG, and GABA molecules. Protein A is often coupled to other molecules such as a fluorescent dye, enzymes, biotin, and colloidal gold or radioactive iodine without affecting the antibody binding site. In addition, the capacity of Protein A to bind antibodies with such high affinity is the driving motivation for its industrial scale use in biologic pharmaceuticals. Therefore, measuring Protein A binding is a useful method with which to verify the function of the biosensor. IgG is the most abundant antibody isotype found in the circulation. By binding many kinds of pathogens including viruses, bacteria, and fungi, IgG protects the body from infection. Also, IgG can bind with Protein A well so the biosensor here could also measure IgG after a Protein A layer is immobilised on the sensing area. GABA is the main inhibitory neurotransmitter in the mammalian central nervous system. It plays an important role in regulating neuronal excitability throughout the nervous system. The conventional method to measure concentrations of GABA under the extracellular conditions is by using liquid chromatography. However, the disadvantages of chromatographic methods are baseline drift and additions of solvent and internal standards. Therefore, it is necessary to develop a simple, rapid and reliable method for direct measurement of GABA, and the sensor here is an attractive choice. When the Love wave sensor works in the liquid media, it can only be used to measure the mass of analytes but does not provide information about the conditions of molecules bound with the sensing surface. In contrast, electrochemical impedance sensing based on the diffusion of redox species to the underlying metal electrode can provide real-time monitoring of the surface coverage of bound macromolecular analytes regardless of the mechanical strength of the analyte-substrate bond: the electrochemical impedance measurement is sensitive to the size and extent of the diffusion pathways around the adsorbed macromolecules used by the redox species probe i.e. it is sensitive to the physical area of the surface covered by the macromolecular analyte and not to the mass of material that is sensed through a mechanical coupling effect (as in a Love wave device). Although electrochemical impedance measurements under the dry state are quite common when studying batteries and their redox/discharge properties, these are quite different sorts of systems to the device in this study. Therefore, integrating these two sensors (Love wave sensor and electrochemical impedance sensor) in a single device is a novel concept and should lead to better analytical performance than when each is used on their own. The new type of biosensor developed here therefore has the potential to measure analytes with greater accuracy, higher sensitivity and a lower limit of detection than found when using either a single Love wave sensor or electrochemical impedance sensor alone.
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Barthe, Peter Girard. "Analysis of tapered-thickness piezoelectric ceramics for ultrasonic transducers". Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/15434.
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Giurgea, Constantin. "Precise motion with piezoelectric actuator". Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6184.
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The purpose of this study is to determine the displacement performance of a high accuracy-positioning device equipped with three piezo ceramic actuators. The displacement performance of each individual actuator is investigated in order to perform controlled motion over a very small range. A nanometric precision three-degrees of freedom positioner was designed and fabricated. In order to design a proper closed-loop controller, the open loop characteristics of the nanopositioner were experimentally investigated.
13
Haigh, Richard. "Novel piezoelectric thick film actuators". Thesis, Cranfield University, 2005. http://dspace.lib.cranfield.ac.uk/handle/1826/3814.
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Planar-spiral piezoelectric-unimorph-actuators, that deflect out-of-their-plane, were modelled, designed and fabricated. A range of other planar piezoelectric-device designs has also been made. These include spokes, multi-arms, plates and swastikas. All these devices consisted of a mechanical support in the plane with a piezoelectric layer deposited on top. Impedance spectra demonstrated that a fabricated device was piezoelectrically active. Finite-element (FE) models of straight and spiral piezoelectric- unimorph-actuators were constructed. The mechanical stiffness of the spiral-beam was increased with the curvature of the beam; consequently, the inner coils exhibited virtually no deflection and appeared to be redundant. The advantage of the spiral-actuators is that they allow large actuator lengths to be contained compactly without the loss of mechanical stiffness. Fabrication of the above devices necessitated the development of new fabrication technologies. The active-piezoelectric and mechanical-support were a lead zirconate titanate (Pb(Tii_XZrx)O3 - PZT) thick-film and a-platinised-silicon-wafer respectively. Vias were opened in the PZT with wet etching, and this was completed without damaging the back electrode. Powder blasting allowed any 2-dimensional-shape to be cut into the device wafer. Devices were released from the Si support with deep-reactive-ion-etching (DRIE). The PZT thick films were fired with a Cu20-PbO eutectic additive. Pb and Cu were considered to dope on A and B lattice sites (of PZT) respectively, when the PZT was sintered at high oxygen-partial-pressure (p02). The electrical conductivity of PZT thick films was increased when they were sintered at low P02, and this was moderated by the presence of Cu' as an acceptor ion. A lead-platinum intermetallic and lead silicate glass phase simultaneously formed under sintering conditions of low pot, and this simultaneous formation, was accounted for by a six-stage mechanism. Step 1, residual C in the thick film reduces PbO to Pb followed by step 2 where Pb diffuses into the Pt back electrode. In step 3, Pt3Pb formation occurs in the intermetallic layer followed by step 4 in which PtPb forms. Step 5 occurs with saturation of the intermetallic layer as Pb continues to diffuse from the thick film. There is additional diffusion of Pb into the underlying Si substrate. Finally step 6 occurs at some later point, when P02 has risen, Pb is oxidised to PbO, and Si is oxidised to Si02. PbO and Si02 can flux to form PbSiO3 The glass was found to undermine film/substrate adhesion.
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Kwon, Dongwon. "Piezoelectric kinetic energy-harvesting ics". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47571.
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Wireless micro-sensors can enjoy popularity in biomedical drug-delivery treatments and tire-pressure monitoring systems because they offer in-situ, real-time, non-intrusive processing capabilities. However, miniaturized platforms severely limit the energy of onboard batteries and shorten the lifespan of electronic systems. Ambient energy is an attractive alternative because the energy from light, heat, radio-frequency (RF) radiation, and motion can potentially be used to continuously replenish an exhaustible reservoir. Of these sources, solar light produces the highest power density, except when supplied from indoor lighting, under which conditions the available power decreases drastically. Harnessing thermal energy is viable, but micro-scale dimensions severely limit temperature gradients, the fundamental mechanism from which thermo piles draw power. Mobile electronic devices today radiate plenty of RF energy, but still, the available power rapidly drops with distance. Harvesting kinetic energy may not compete with solar power, but in contrast to indoor lighting, thermal, and RF sources, moderate and consistent vibration power across a vast range of applications is typical. Although operating conditions ultimately determine which kinetic energy-harvesting method is optimal, piezoelectric transducers are relatively mature and produce comparatively more power than their counterparts such as electrostatic and electromagnetic kinetic energy transducers.
The presented research objective is to develop, design, simulate, fabricate, prototype, test, and evaluate CMOS ICs that harvest ambient kinetic energy in periodic and non-periodic vibrations using a small piezoelectric transducer to continually replenish an energy-storage device like a capacitor or a rechargeable battery. Although vibrations in surrounding environment produce abundant energy over time, tiny transducers can harness only limited power from the energy sources, especially when mechanical stimulation is weak. To overcome this challenge, the presented piezoelectric harvesters eliminate the need for a rectifier which necessarily imposes threshold limits and additional losses in the system. More fundamentally, the presented harvesting circuits condition the transducer to convert more electrical energy for a given mechanical input by increasing the electromechanical damping force of the piezoelectric transducer. The overall aim is to acquire more power by widening the input range and improving the efficiency of the IC as well as the transducer. The presented technique in essence augments the energy density of micro-scale electronic systems by scavenging the ambient kinetic energy and extends their operational lifetime.
This dissertation reports the findings acquired throughout the investigation. The first chapter introduces the applications and challenges of micro-scale energy harvesting and also reviews the fundamental mechanisms and recent developments of various energy-converting transducers that can harness ambient energy in light, heat, RF radiation, and vibrations. Chapter 2 examines various existing piezoelectric harvesting circuits, which mostly adopt bridge rectifiers as their core. Chapter 3 then introduces a bridge-free piezoelectric harvester circuit that employs a switched-inductor power stage to eliminate the need for a bridge rectifier and its drawbacks. More importantly, the harvester strengthens the electrical damping force of the piezoelectric device and increases the output power of the harvester. The chapter also presents the details of the integrated-circuit (IC) implementation and the experimental results of the prototyped harvester to corroborate and clarify the bridge-free harvester operation.
One of the major discoveries from the first harvester prototype is the fact that the harvester circuit can condition the piezoelectric transducer to strengthen its electrical damping force and increase the output power of the harvester. As such, Chapter 4 discusses various energy-investment strategies that increase the electrical damping force of the transducer. The chapter presents, evaluates, and compares several switched-inductor harvester circuits against each other. Based on the investigation in Chapter 4, an energy-investing piezoelectric harvester was designed and experimentally evaluated to confirm the effectiveness of the investing scheme. Chapter 5 explains the details of the IC design and the measurement results of the prototyped energy-investing piezoelectric harvester. Finally, Chapter 6 concludes the dissertation by revisiting the challenges of miniaturized piezoelectric energy harvesters and by summarizing the fundamental contributions of the research. With the same importance as with the achievements of the investigation, the last chapter lists the technological limits that bound the performance of the proposed harvesters and briefly presents perspectives from the other side of the research boundary for future investigations of micro-scale piezoelectric energy harvesting.
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Baker, Daniel William. "Lead-free piezoelectric niobate perovskites". Thesis, University of Warwick, 2010. http://wrap.warwick.ac.uk/3894/.
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The structure and physical properties of the lead-free piezoelectric niobate perovskite material sodium potassium niobate, KxNa1-xNbO3 (KNN) have been investigated via a variety of experimental techniques. High- and low-temperature X-ray and neutron powder diffraction has been performed on polycrystalline samples of KNN. Rietveld refinement has been carried out on data for samples of KNN from x = 0:1 to x = 0:85, with the structure determined for each sample. The phase diagram from x=0:1 to x=1 has been determined, with particular attention paid to the oxygen octahedra tilt systems. The proposed compositionally-driven phase transitions were also investigated, and it has been found that changes in the tilt system occur at x = 0:2 and x = 0:4 at room temperature, which is a correction to previously published work. The first-order phase transition at x = 0:5 from a monoclinic structure to an orthorhombic structure has also been confirmed. To complement the polycrystalline structural analysis, single-crystal samples of KNN have been fabricated to confirm the exact nature of the tilt systems. It has been found that all crystals possess the same merohedral twinning that is present for other perovskite systems that follow a similar phase transition path from the prototypic cubic phase. The tilt systems above and below the the x=0:2 boundary have been found to be of the type a0b+c0 and a-b+c- respectively. Low-temperature single-crystal diffraction also confirmed the structure of the low-temperature trigonal (rhombohedral) phase. To complement the diffraction work, the short-range structure of KNN has been investigated with 1D and 2D 23Na NMR experiments. It has been found that chemical shift dispersion is present for all samples of KNN because of the shared A-site occupancy of potassium and sodium atoms. The quadrupolar parameters have been determined, and an increase in the electric field gradient for one sodium site can be seen to coincide with an increase in the distortion in the structure because of the tilting of the oxygen octahedra. Birefringence data have been collected for single-crystal samples of KNN using the Metripol technique. No obvious domain structure was seen. The nature of the phase transition from the prototypic cubic phase and the tetragonal phase was investigated, and the analysis suggests that the transition is at a tricritical point between a first-order and a second-order phase transition. Finally, an optical study was performed on samples of KNbO3 (KN) using the Metripol technique. Large self-organised domains similar to those previously observed in barium titanate were seen only on the first heating run. Very small (< 5μm) domains were observed in the samples, and remained in the orthorhombic phase after several heating runs. Single-crystal X-ray diffraction was implemented to determine the structure of the sample. It was also found that same twin law as in barium titanate is present for KN.
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Wu, Zhengbin. "Bondlines in piezoelectric ultrasonic transducers". Thesis, University of the West of Scotland, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427721.
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Wright, Darryn John. "New piezoelectric and pyroelectric polymers". Thesis, University of Leeds, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437100.
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Sanson, Alessandra. "Modified bismuth titanate piezoelectric ceramics". Thesis, Cranfield University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401625.
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Rayner, Philip. "Piezoelectric ultrasonic motors and micromotors". Thesis, Cranfield University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323890.
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Pathak, Shrey. "Piezoelectric microsensors for semiochemical communication". Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/57210/.
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Chemical communication plays vital role in the mediating the behaviour of an organism living in the “odour space”. The mechanisms by which odours are generated and detected by the organism has evolved over thousands of years and thus the potential advantages of translating this system into a fully functional communication system has opened new avenues in the area of multi-disciplinary research. This formed the basis of the Biosynthetic Infochemical Communications project – iCHEM whose central aim was to develop a new class of communication technology based on the biosynthesis pathways of the moth, S. littoralis. This novel infochemical communication system would consist of a “chemoemitter” unit which would generate a precise mix of infochemicals which after travelling through the odour space would be detected by a complementary tuned detector – the “chemoreceiver” unit comprising of a ligand specific detection element and an associated biophysical model functioning similar to the antennal lobe neuron of the moth. This combined novel system will have the capability of communicating by the help of chemicals only, in the vapour or liquid phase. For the work presented in this thesis, the novel concept of infochemical communication has been examined in the vapour and liquid phase by employing piezoelectric microsensors. This has been achieved and demonstrated throughout the thesis by employing chemo-specific acoustic wave microsensors. For vapour phase assessment, quartz crystal microbalance, were coated with different organic polymer coatings and incorporated in a prototype infochemical communication system detecting encoded volatiles. For liquid phase assessment, shear horizontal surface acoustic wave (SH-SAW) microsensors were specifically designed and immobilised within Sf9 insect cells. This GPCR based whole cell biosensing system was then employed to detect ligand specific activations thus acting as a precursor to the development of a fully functionalised OR based signalling system, thus contributing to the growing field of communication and labelling technology.
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Pantzare, Sandra, i Elin Wollert. "Wireless Piezoelectric Horse Sensor System". Thesis, Linköpings universitet, Fysik och elektroteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-150152.
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The domestication of horses took place at least 2000 BCE. Since then, horses have been used for transportation, agricultural work and even for warfare. Today, horses have been bred into world athletes, used worldwide in equestrian sports. However, these explosive performance horses present characteristics that make them prone to injuries leading to lameness. According to the insurance company Agria, more than 50 % of all reported injuries on horses in Sweden each year, are related to lameness. Using more objective analysing methods can lead to earlier detection and decrease the occurrence of this kind of injuries. In this Master’s degree project, a horse sensor system was proposed, designed and manufactured as a first prototype. The system consists of a force measuring device and an external reader. The force measuring sensor itself is a piezoelectric printed sensor. The force measuring device senses, acquires and transmits the raw data to the external reader. The focus of this project was on the hardware- and software development of the force measuring device and the software development for the external reader. To develop and verify the algorithms, as well as the entire system concept, the CC1352R1 Launchpad from Texas Instruments was used. The first results have indicated that the developed hardware and software of the force measuring device performs as expected. Also, important conclusions were drawn for both the force measuring device and the external reader. E.g., the force measuring device should fit the required physical dimension of the hoof sole, and the algorithms of the external reader should be improved in terms of data flow and memory usage. To conclude, the project is a challenging application making use of modern wireless sensor technology and printed electronics.
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Ely, Kevin Jon. "Piezoelectric effects in GaAs MESFET's". Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40029.
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Gallium arsenide MESFETS require protective passivation at several steps in their fabrication. A common film used for device passivation is silicon nitride. This passivation film is deposited on gallium arsenide substrates by chemical vapor deposition techniques and possesses high intrinsic stress. The stresses arise from the difference in the gallium arsenide and silicon nitride material properties, such as coefficient of expansion, density, modulus, and deposition temperature. The stress has been shown to cause electrical performance shifts in GaAs MESFET structures due to the piezoelectric nature of the gallium arsenide lattice.
This work develops a framework of mathematical models and experimental techniques by which the intrinsic stresses in the film and the GaAs substrate can be evaluated. Specifically, this work details the stress field and the electrical performance shifts in fully planarized self aligned gate GaAs MESFETS. The devices were 10 micron gate periphery FET devices with a 0.4 micron etched gate length. The test devices included both enhancement mode and depletion mode structures. The major contributors to the stress in GaAs devices was found to be the intrinsic stress effects of the silicon nitride passivation film. An externally applied stress, such as that applied to a package base that a typical GaAs device would be mounted into for actual service, was found to be insufficient to cause significant shifts in the device performance. The package body effectively reduces the transfer of stress to the device body and thereby minimizes the piezoelectric effect. The intrinsic stress effects are due to the deposition of the film itself. This intrinsic stress was found to have a significant effect on the device electrical characteristics. The stress was found to permanently shift the threshold voltage and current in 10 micron self aligned gate MESFETS. The shift was measured at 26 millivolts per 100 MPa film stress for depletion mode devices and 23 millivolts per 100 MPa for enhancement mode devices. For the maximum measured biaxial stress of -0.54 MPa in the gallium arsenide, the total measured shift was 140 millivolts. The level of shift is similar to that reported by earlier researchers. This piezoelectric shift has been modeled, with model predictions within 50/0 of the experimental values for the DFET devices and 11 % for the EFET devices.Ph. D.
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Bazilo, C. V., V. M. Zaika, Yu Yu Bondarenko, Yu A. Petrushko i L. O. Fedoruk. "Piezoelectric Transducers for Ultrasonic Surgery". Thesis, Sumy State University, 2017. http://essuir.sumdu.edu.ua/handle/123456789/65125.
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To enhance the acoustic oscillations it is proposed to place piezoelectric
elements on a scalpel in such way to have an angle between the electric
field vector of the excitation voltage and the polarization vector.
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Anton, Steven Robert. "Multifunctional Piezoelectric Energy Harvesting Concepts". Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/27388.
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Energy harvesting technology has the ability to create autonomous, self-powered electronic systems that do not rely on battery power for their operation. The term energy harvesting describes the process of converting ambient energy surrounding a system into useful electrical energy through the use of a specific material or transducer. A widely studied form of energy harvesting involves the conversion of mechanical vibration energy into electrical energy using piezoelectric materials, which exhibit electromechanical coupling between the electrical and mechanical domains. Typical piezoelectric energy harvesting systems are designed as add-on systems to a host structure located in a vibration rich environment. The added mass and volume of conventional vibration energy harvesting designs can hinder to the operation of the host system. The work presented in this dissertation focuses on advancing piezoelectric energy harvesting concepts through the introduction of multifunctionality in order to alleviate some of the challenges associated with conventional piezoelectric harvesting designs.
The concept of multifunctional piezoelectric self-charging structures is explored throughout this work. The operational principle behind the concept is first described in which piezoelectric layers are directly bonded to thin-film battery layers resulting in a single device capable of simultaneously harvesting and storing electrical energy when excited mechanically. Additionally, it is proposed that self-charging structures be embedded into host structures such that they support structural load during operation. An electromechanical assumed modes model used to predict the coupled electrical and mechanical response of a cantilever self-charging structure subjected to harmonic base excitation is described. Experimental evaluation of a prototype self-charging structure is then performed in order to validate the electromechanical model and to confirm the ability of the device to operate in a self-charging manner. Detailed strength testing is also performed on the prototype device in order to assess its strength properties. Static three-point bend testing as well as dynamic harmonic base excitation testing is performed such that the static bending strength and dynamic strength under vibration excitation is assessed. Three-point bend testing is also performed on a variety of common piezoelectric materials and results of the testing provide a basis for the design of self-charging structures for various applications.
Multifunctional vibration energy harvesting in unmanned aerial vehicles (UAVs) is also investigated as a case study in this dissertation. A flight endurance model recently developed in the literature is applied to model the effects of adding piezoelectric energy harvesting to an electric UAV. A remote control foam glider aircraft is chosen as the test platform for this work and the formulation is used to predict the effects of integrating self-charging structures into the wing spar of the aircraft. An electromechanical model based on the assumed modes method is then developed to predict the electrical and mechanical behavior of a UAV wing spar with embedded piezoelectric and thin-film battery layers. Experimental testing is performed on a representative aluminum wing spar with embedded self-charging structures in order to validate the electromechanical model. Finally, fabrication of a realistic fiberglass wing spar with integrated piezoelectric and thin-film battery layers is described. Experimental testing is performed in the laboratory to evaluate the energy harvesting ability of the spar and to confirm its self-charging operation. Flight testing is also performed where the fiberglass spar is used in the remote control aircraft test platform and the energy harvesting performance of the device is measured during flight.
Ph. D.
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Morvan, Jason. "HIGHLY PIEZOELECTRIC SOFT COMPOSITE FIBERS". Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1334585220.
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Xiong, Haocheng. "Piezoelectric Energy Harvesting for Roadways". Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51361.
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Energy harvesting technologies have drawn much attention as an alternative power source of roadway accessories in different scales. Piezoelectric energy harvesting consisting of PZT piezoceramic disks sealed in a protective package is developed in this work to harness the deformation energy of pavement induced by traveling vehicles and generate electrical energy. Six energy harvesters are fabricated and installed at the weigh station on I-81 at Troutville, VA to perform on-site evaluation. The electrical performance of the installed harvesters is evaluated by measuring the output voltage and current generated under real traffic. Instant and average power outputs are calculated from the measured waveforms of output voltage and current. The analysis of the testing results shows that the electrical productivity of the energy harvesters are highly relevant to the axle configuration and magnitude of passing vehicles. The energy transmission efficiency of the energy harvester is also assessed.Ph. D.
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Zhang, Jin. "Mechanical behaviours of piezoelectric nanostructures". Thesis, Swansea University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678635.
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The objective of this thesis is to present a modelling and simulation study for the mechanics of PNs with an emphasis placed on the unique features of PNs due to the piezoelectric and small scale effects.
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Capobianco, Joseph A. Shih Wan Y. Shih Wei-Heng. "Piezoelectric microcantilever serum protein detector /". Philadelphia, Pa. : Drexel University, 2009. http://hdl.handle.net/1860/2993.
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Sullivan, Timothy Michael. "Development of a novel method for measuring the transverse piezoelectric coefficients of thin piezoelectric films". Online access for everyone, 2004. http://www.dissertations.wsu.edu/Thesis/Summer2004/t%5Fsullivan%5F072604.pdf.
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Bing, Yonghong. "Synthesis, structure and properties of high piezo-and ferroelectric complex perovskite systems /". Burnaby B.C. : Simon Fraser University, 2005. http://ir.lib.sfu.ca/handle/1892/2032.
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Mtawa, Alexander Nikwanduka. "Influence of geometry and material properties on the optimum performance of the C-shape piezo-composite actuator". Thesis, Cape Peninsula University of Technology, 2008. http://hdl.handle.net/20.500.11838/1301.
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Thesis (DTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2008In recent years, due to rapid advances in technology there has been an increasingly high demand for large displacement and large force, precise positioning, fast response, low power consuming miniature piezoelectric actuators. In certain smart structure applications, the use of curved piezoelectric actuators is necessary. The present work extends the earlier investigations on the C- shape actuator by providing a detailed investigation on the influence of geometric and material properties of the individual layers of the C-shape piezocomposite for its optimal performance as an actuator. Analytical models have. been used to optimize the geometry of the actuator. Experimental and finite element analyses (using general purpose finite element software i.e. CoventerWare and MSC. Marc) have been used for validation. The present work has established that, by maintaining the thickness of the substrate and piezoceramic layers constant; changing the external radius, for example increasing it, the stiffness of the structure decreases and thus yielding large displacement This has a negative effect on the force produced by the actuator. With fixed thickness of the substrate and varying the thickness of the piezoceramic (for fixed external radius) the result is as follows: Increasing the thickness of the piezoceramic layer has the effect of decreasing the displacement while the force increases. With fixed PZT thickness as well as the external radius, varying the substrate thickness has the following effect: As the thickness of the substrate increases the displacement increases reaching a maximum. Subsequent increase in the thickness of the substrate the displacement is reduced. The force continues increasing at least for the ratios up to 1.0, further increase of the substrate, subsequent decrease of force is also noted. In addition to changing the thickness of the substrate, the choice of different material for the substrate has the following effect: For substrate/PZT ratios of up to 0.6. an actuator with substrate material having higher elastic modulus will produce larger displacement while for ratios beyond this ratio the situation is reversed. The causes for this kind of behaviour have been addressed. In all cases both force and displacement are found to be directly proportional to applied voltage.
32
Shen, Zuyan Shih Wan Y. Shih Wei-Heng. "Synthesis, fabrication, and characterization of self-exciting, self-sensing PZT/SiO2 piezoelectric micro-cantilever sensors /". Philadelphia, Pa. : Drexel University, 2006. http://hdl.handle.net/1860/1227.
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Stoll, William Allard III. "Nonlinear constitutive behavior of PZT". Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/17117.
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Mika, Bartosz. "Design and testing of piezoelectric sensors". [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1565.
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Gomis-Bellmunt, Oriol. "Identification and control of piezoelectric actuators". Saarbrücken VDM Verlag Dr. Müller, 2007. http://d-nb.info/988454696/04.
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Dickens, Robert A. "Optimization of a piezoelectric acoustical compressor". College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/181.
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Thesis (M.S.) -- University of Maryland, College Park, 2004.Thesis research directed by: Dept. of Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
37
Wang, Weijian. "Electrode shape optimization of piezoelectric transducers". [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001041.
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Lin, Ting-Kuang, i 林廷光. "Research of Dielectrics and Piezoelectrics in Piezoelectric Ceramics". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/97778568764655146235.
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Shivashankar, P. "Analytical Modelling and Non-linear Characterisation of Piezoelectric Materials for Actuation and Vibration Control of Beams". Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4011.
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The use of piezoelectric materials for actuation, and vibration suppression of thin beams, is the subject of study in this doctoral thesis. The initial focus is set on reducing beam vibrations with resistively shunted piezoelectric patches, where the converted electrical energy is dissipated by the resistor to give an additional damping. The amount of additional damping achieved depends on the value of shunted resistor, the dimensions of the piezoelectric, and its location on the substructure. Hence, the resistively shunted piezoelectric-beam was modelled to determine the optimal values, and to examine its dynamics. A multi-modal model was derived based on the Euler-Bernoulli beam theory, and a reduced non-dimensionalized transfer function was obtained from the multi-modal model. The presented model was derived from assumptions which aptly describe the dynamics of the resistively shunted piezoelectric-beam. The aptness of the presented model in representing the system, over the existing models, was evident from the comparison of the analytical predictions with the existing experimental data.
With the model derived, the second part of the work deals with determining the value of resistance which would yield maximum amplitude attenuation (referred as the optimal resistance value). A method for obtaining the optimal resistance value from the analytical model, based on the presence of a fixed-point in the amplitude response, exists in the literature. But, this method cannot be used on the presented analytical model, as it includes the base-damping of the structure. Hence, a different approach was adopted to determine the optimal resistance from the analytical model. Analytical results were also validated with experimental results from a cantilever piezoelectric-beam.
The amplitude plots of the first, second, and third modes of the piezoelectric-beam exhibited a softening e ect, indicating a non-linear behaviour of the piezoelectric patches. Hence, a non-linear constitutive equation was required to describe the behaviour of the piezoelectric patches. In the third part of the work, a two-step experimental procedure was devised to construct the non-linear constitutive equation of the piezoelectric actuators. In the first step, the piezoelectric patches were short circuited and a family of displacement curves were obtained for the first, second and third modes of the piezoelectric-beam by base excitation. The pro le of backbone curves from these plots were used to identify the type of non-linear terms required to describe the mechanical domain. In the second step, voltage excitation was used to obtain a similar set of displacement curves. A comparison of the profile of the backbone curves, of the displacement frequency response plot, from the voltage excited data with those from the base excited data, lead to the identification of the non-linear electromechanical coupling term. The constitutive equation, which accounts for the non-linear nature, of the piezoelectric actuator contains (apart from the linear terms) a quadratic strain term, a cubic strain term, and a term with the product of cubic strain and electric field.
40
Shivashankar, P. "Analytical Modelling and Non-linear Characterisation of Piezoelectric Materials for Actuation and Vibration Control of Beams". Thesis, 2017. http://etd.iisc.ernet.in/2005/3990.
Pełny tekst źródłaStreszczenie:
The use of piezoelectric materials for actuation, and vibration suppression of thin beams, is the subject of study in this doctoral thesis. The initial focus is set on reducing beam vibrations with resistively shunted piezoelectric patches, where the converted electrical energy is dissipated by the resistor to give an additional damping. The amount of additional damping achieved depends on the value of shunted resistor, the dimensions of the piezoelectric, and its location on the substructure. Hence, the resistively shunted piezoelectric-beam was modelled to determine the optimal values, and to examine its dynamics. A multi-modal model was derived based on the Euler-Bernoulli beam theory, and a reduced non-dimensionalized transfer function was obtained from the multi-modal model. The presented model was derived from assumptions which aptly describe the dynamics of the resistively shunted piezoelectric-beam. The aptness of the presented model in representing the system, over the existing models, was evident from the comparison of the analytical predictions with the existing experimental data.
With the model derived, the second part of the work deals with determining the value of resistance which would yield maximum amplitude attenuation (referred as the optimal resistance value). A method for obtaining the optimal resistance value from the analytical model, based on the presence of a fixed-point in the amplitude response, exists in the literature. But, this method cannot be used on the presented analytical model, as it includes the base-damping of the structure. Hence, a different approach was adopted to determine the optimal resistance from the analytical model. Analytical results were also validated with experimental results from a cantilever piezoelectric-beam.
The amplitude plots of the first, second, and third modes of the piezoelectric-beam exhibited a softening e ect, indicating a non-linear behaviour of the piezoelectric patches. Hence, a non-linear constitutive equation was required to describe the behaviour of the piezoelectric patches. In the third part of the work, a two-step experimental procedure was devised to construct the non-linear constitutive equation of the piezoelectric actuators. In the first step, the piezoelectric patches were short circuited and a family of displacement curves were obtained for the first, second and third modes of the piezoelectric-beam by base excitation. The pro le of backbone curves from these plots were used to identify the type of non-linear terms required to describe the mechanical domain. In the second step, voltage excitation was used to obtain a similar set of displacement curves. A comparison of the profile of the backbone curves, of the displacement frequency response plot, from the voltage excited data with those from the base excited data, lead to the identification of the non-linear electromechanical coupling term. The constitutive equation, which accounts for the non-linear nature, of the piezoelectric actuator contains (apart from the linear terms) a quadratic strain term, a cubic strain term, and a term with the product of cubic strain and electric field.
41
Chien-Cheng, Chen. "A Thermo-piezoelectric Finite-element Solver for Piezoelectric Transformers". 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-1807200613280900.
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Huang, I.-Ren, i 黃以仁. "Piezoelectric Properties of Cement Piezoelectric Composites with Reactive Powders". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/737gbm.
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碩士國立高雄應用科技大學
土木工程與防災科技研究所
103
0-3 cement-based piezoelectric composite (PP material) consisting of PZT as the inclusion and cement as the binder, with 50% by volume each. While 11.1% and 11.4% of cement were replaced, respectively, by quartz flour and silica fume, the composite is called reactive powders cement piezoelectric composites (PR material). To investigate the effect of silica-based materials, six admixtures: slag, fly ash, glass powder, diatomaceous earth, silicon and silicon carbide were added to PR material to examine its piezoelectric properties. The admixture was a replacement of partial silica fume in PR material. The content of admixture for slag and fly ash is 10% to 50%, and the others are 2% to 10%. Specimens were fabricated by 80MPa compression and cured at 90℃ for 24h. After that, specimens were put in 150℃ silicon oil bath by applying 1.5kV/mm electric field for 40 min to obtain piezoelectric properties. Experimental results indicate that PR materials with no water during the process of manufacturing always have the optimum piezoelectric strain constant d33 and dielectric constant r, compared with that adding water. This is because water will provide more voids inside the specimen that affects the propagation of applied stress inducing lower piezoelectric properties. From the observations of optical microscope, adding quartz flour and silica fume to PP material can reduce the content of voids. However, void content of PR materials increases with increasing slag and fly ash. Before the polarization, the capacity C and dielectric loss of PR materials increase with increasing admixtures, and this leads to extend trigger time during the polarization. The age for saturated values of piezoelectric properties of PR material is about 30 days, and that is early than for PP material with 50 days. PR materials with 2% glass powder (PG-2) always the highest value of d33 and r, where d33=124.4pC/N and r =593. The resonance frequency of PP materials is 105.025 kHz ~ 125.126 kHz and that is lower than the PP material.
43
Chen, Chien-Cheng, i 陳建誠. "A Thermo-piezoelectric Finite-element Solver for Piezoelectric Transformers". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/05047937446431794167.
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碩士國立臺灣大學
機械工程學研究所
94
In this work, we develop a 3-D FEM solver, NTUPZE-T for analyzing piezoelectric transformers. This solver is capable of estimating the device thermal effects. In order to estimate the device temperature distribution when the device operates, we calculate the dissipation of energy based on the internal damping effects. The dissipated energy is considered as the heat source of the heat transfer equation for calculating the temperature distribution of a device. Material constants of piezoelectric materials are usually dependent on temperature. Therefore, a self-consistent thermo-piezoelectric analysis procedure is proposed. In this work, we employ the relaxation algorithm for self-consistently computing the solutions in the piezoelectric domain and the thermal domain. Then the voltage gains, phase difference, efficiencies, as well as the temperature distribution of the device at difference frequencies and loadings can be obtained by the solver. The solver employs 20-node brick-element formulation for the discretization. We analyzed Rosen -modal-type piezoelectric transformer. The simulated results of voltage gains, efficiencies, resonant frequencies, and temperature increase of the device were also verified with the measured results.
44
Tseng, Wen-Tse, i 曾文澤. "Studies on Piezoelectric Properties of Porous Piezoelectric Ceramic╱Polymer Composites". Thesis, 1995. http://ndltd.ncl.edu.tw/handle/92029441850716683061.
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碩士國立成功大學
電機工程研究所
83
In the underwater sonar system, traditional lead zirconate titanate (PZT) piezoelectric ceramics have been widely used as all kinds of electro-acostical transducers due to their excellent piezoelectricity. However, when PZT ceramics applied in the underwater pressure sensor and hydrophone fields,they become low efficient because their sensitivity will reduce due to the high dielectric constants. In order to improve the efficiency, the composite and porous technology have been developed and applied on electro-acostical transducers gradually. This article uses the method of composing the porous PZT ceramic and polymer and hopes to reduce their dielectric constants to increase their sensitivity. Besides, we will study the changes of piezoelectricity of different polymer composites to get a better piezoelectric composite material for the underwater applications.
45
SU, I.-HSUAN, i 蘇逸軒. "Piezoelectric and Electromechanical Properties of Piezoelectric Cement with Quartz Powder". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/2n69rc.
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碩士國立高雄應用科技大學
土木工程與防災科技研究所
105
Piezoelectric Cement (Cement Piezoelectric Composites) is a new type of sensor that can be used as the health detection and diagnosis of RC structures. The piezoelectric constants of piezoelectric cement are closely related to their electromechanical properties. Constant piezoelectric cement by the load will have a higher output voltage, in order to create a higher piezoelectric constant piezoelectric cement, the study added the right amount of quartz powder to form a new type of sensor for the quartz powder piezoelectric cement The In this study, the PZT ceramic content of piezoelectric cement is 30 ~ 70%, and the volume of quartz powder is 1%, 2%, 3%, 4%, 5% and 6%. Temperature treatment variables are AA = 23℃-23℃, AB = 23℃-140℃, BA = 140℃-23℃, BB = 140℃-140℃ four. To 100N, 200N, 300N load and 1Hz, 2Hz, 4Hz frequency load, the measurement of quartz powder piezoelectric cement output voltage. The results show that quartz powder PZT fixed 50% content, mixed with quartz powder content from 1% to 6%, of which 4% quartz powder piezoelectric cement piezoelectric properties of the best = 96.55pC / N, = 859.64, 4% quartz powder piezoelectric cement = 17.12%, the amount of mixed with quartz powder to enhance the piezoelectric properties. The piezoelectric cement is between 19.14 and 103.45 pC / N, BB is between 61.70 and 137.46 pC / N, and the quartz powder piezoelectric cement AA is between 44.14 and 96.55 pC / N, and BB were between 92.45 and 148.44 pC / N, indicating that the temperature of the sample could increase the piezoelectric strain constant. The electromechanical coupling constant of piezoelectric cement is between 10.11% and 19.00%, and the quartz powder piezoelectric cement is between 12.99% and 17.12%, but the electromechanical coupling constant after temperature treatment has some slight decrease. Force test results, 50% of the piezoelectric cement in the load of 300N obtained by the best output voltage of 850mV, quartz powder piezoelectric cement mixed with 4% content of the piezoelectric strain constant is best = 148.44 pC / N, the 300N output voltage Is 1121mV, showing that the higher the piezoelectric strain constant of the quartz powder is given, the higher the output voltage is.
46
Yeh, Yu-Chung, i 葉俞均. "Piezoelectric Ceramics Transformer". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/21807343980157655421.
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碩士國立中央大學
光電科學研究所
92
Along with the invention of piezoelectric ceramic, there were many other small-sized but highly efficiency- transformed devices being researched and developed since then. In order to reduce the volume of power supplies and raise its efficiency simultaneously, researchers use piezoelectric transformers made by piezoelectric ceramic to serve their purpose. This thesis focuses in the piezoelectricity of piezoelectric ceramic, how to motivate a piezoelectric transformer, and how to use piezoelectric transformers to drive the backlight source.
47
Lin, Chih-Ting, i 林致廷. "Redeployment of Piezoelectric Point Sensor by Using Distributed Piezoelectric Sensor Technology". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/01602834485433449821.
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碩士國立臺灣大學
應用力學研究所
86
Point sensors and distributed sensors have both been developed for several decades. The advantages of point sensors as compared to distributed sensors are quite different and both have their own limitations. Based on the linear piezoelectric sensor theory, piezoelectric point sensors and piezoelectric distributed sensors have been developed. A sensor model has been investigated and established. The experimental result to verify the unique characteristics of the piezoelectric sensor as well as the distributed point sensor. Based on the integrated distributed and point sensor, an innovative distributed accelerometer has been developed. The design principle as well as application implications of this newly developed accelerometer are detailed.
48
YOUNG, SHIN WEN, i 楊實文. "Piezoelectric Inkjet Head- Design and Fabrication of Micro Array Piezoelectric Actuator". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/14146311682979223353.
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碩士大葉大學
機械工程學系碩士班
91
With the development of inkjet printing application technology, the inkjet print-head is not only occupying the traditional office printing market, but also making us to focus on it’s application, such as new organic/polymer lighting emitting display, optical communication devices, and MEMS devices, and engine technology etc. In many kinds of inkjet printing technology, the most favor type of inkjet printing technology is the piezoelectric driven printing technology. This study uses finite elements code, ANSYS, to analyze and design an actuator of a new type of shear mode piezoelectric ink jet head. Base on the actuated displacement and stoke volume change, the newly designed actuator model was optimized. The advantage of the model is use the most developed technology of making piezoelectric bulk. The piezoelectric actuator is poled by surface poling process, and owned different poling direction in the same piezoelectric material. Using electroplate process to fabricate a vibration membrane. Bonding both by epoxy and cutting the modulus by dicing saw. Measure the modulus properties such as displacement and compare with numerical simulation.
49
Hung, Sheng-Wei, i 洪聖瑋. "Synchronized Switch Harvesting Using Piezoelectric Oscillators for Piezoelectric Energy Harvesting System". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/u794m8.
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碩士國立臺灣大學
工程科學及海洋工程學研究所
107
In order to replace the traditional battery, the concept of energy harvesting has been proposed and attracted widespread attention. Using the micro-piezoelectric transducer for extracting ambient energy is now a popular research topic. The piezoelectric energy harvesting system consists of a piezoelectric transducer, a load device, and interface circuits, which usually includes a rectifier and a DC/DC converter. In general, a full-bridge rectifier is used to convert AC source into DC voltage because it is easy to implement. However, the it has low power efficiency since its low power factor and forward voltage of the diodes consume large amounts of energy. As a result, more and more rectifiers with nonlinear synchronous switch harvesting techniques are proposed to improve the efficiency. Majority of which use inductors extract more energy by realizing voltage inversion and load independent; however, the inductor which is magnetic a component would generate electromagnetic waves and induce the electromagnetic interference. Therefore, this thesis proposes a new architecture-Synchronized Switch Harvesting using Piezoelectric Oscillators (SSHO) for solving these problem. Without bulky external inductors SSHO achieves voltage inversion which increases the voltage amplitude and then the output power. In this thesis, the SSHO rectifier fabricated in TSMC 0.25 μm HV-CMOS process has executed and tape-out. According to the post-layout simulation results, the circuit can boost the output power up to 475% when the equivalent current source of the piezoelectric source is 25 μA, the parasitic capacitance is 15 nF, and the vibration frequency is 125 Hz.
50
Patterson, Eric Andrew. "Development, characterization, and piezoelectric fatigue behavior of lead-free perovskite piezoelectric ceramics". Thesis, 2012. http://hdl.handle.net/1957/34828.
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Much recent research has focused on the development lead-free perovskite piezoelectrics as environmentally compatible alternatives to lead zirconate titanate (PZT). Two main categories of lead free perovskite piezoelectric ceramic systems were investigated as potential replacements to lead zirconate titanate (PZT) for actuator devices. First, solid solutions based on Li, Ta, and Sb modified (K���.���Na���.���)NbO��� (KNN) lead-free perovskite systems were created using standard solid state methods. Secondly, Bi-based materials a variety of compositions were explored for (1-x)(Bi���.���Na���.���)TiO���-xBi(Zn���.���Ti���.���)O��� (BNT-BZT) and Bi(Zn���.���Ti���.���)O������(Bi���.���K���.���)TiO������(Bi���.���Na���.���)TiO��� (BZT-BKT-BNT).
It was shown that when BNT-BKT is combined with increasing concentrations of Bi(Zn[subscript 1/2]Ti[subscript 1/2])O��� (BZT), a transition from normal ferroelectric behavior to a material with large electric field induced strains was observed. The higher BZT containing compositions are characterized by large hysteretic strains (> 0.3%) with no negative strains that might indicate domain switching. This work summarizes and analyzes the fatigue behavior of the new generation of Pb-free piezoelectric materials. In piezoelectric materials, fatigue is observed as a degradation in the electromechanical properties under the application of a bipolar or unipolar cyclic electrical load. In Pb-based materials such as lead zirconate titanate (PZT), fatigue has been studied in great depth for both bulk and thin film applications. In PZT, fatigue can result from microcracking or electrode effects (especially in thin films). Ultimately, however, it is electronic and ionic point defects that are the most influential mechanism.
Therefore, this work also analyzes the fatigue characteristics of bulk polycrystalline ceramics of the modified-KNN and BNT-BKT-BZT compositions developed. The defect chemistry that underpins the fatigue behavior will be examined and the results will be compared to the existing body of work on PZT. It will be demonstrated that while some Pb-free materials show severe property degradation under cyclic loading, other materials such as BNT-BKT-BZT essentially exhibit fatigue-free piezoelectric properties with chemical doping or other modifications. Based on these results, these new Pb-free materials have great potential for use in piezoelectric applications requiring a large number of drive cycles such as MEMS devices or high frequency actuators.Graduation date: 2013