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1
Al-Bader, Yousef A. "Development of a piezoelectric bone substitute material." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249905.
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Zapletal, Vít. "Analýza SMART zdrojů elektrické energie pro železniční dopravu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378740.
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This master thesis deal with analysis of possible alternative energy sources for health monitoring of railway trafic. Mainly focus on energy harvesting via SMART materials, specifically materials with piezoelectric and magnetostrictive properties. First theoretical background and real concepts are introduced, followed by material modelling and simulations. End of thesis cover parameter suggestion and SMART materials comparation and valorizations.
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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.
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Tam, Yin-king, and 譚燕琼. "Organometallic complexes as coating material for crystal sorptiondetector." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B31207443.
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Tam, Yin-king. "Organometallic complexes as coating material for crystal sorptiondetector /." [Hong Kong : University of Hong Kong], 1985. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12319636.
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Kuri, Salvador Rodriguez. "An investigation into photo-piezoelectric composite material for building integration." Thesis, University of Nottingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493112.
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There is a growing concern for the consequences on climate change due to the increased concentration of greenhouse gases in the atmosphere. Integration of renewable energy technologies such as photovoltaic arrays and small wind turbines into buildings can alleviate the reliance on fossil fuelled energy supply.
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Sreeramakavacham, Bindu. "FILM GROWTH OF NOVEL FREQUENCY AGILE COMPLEX-OXIDE PIEZOELECTRIC MATERIAL." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3104.
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Piezoelectric materials are well known for their applications in surface (SAW) and bulk acoustic wave (BAW) devices such as oscillators, resonators and sensors. Quartz has been the main material used in such applications. Ternary calcium gallium germanate (CGG) structure-type materials, so-called langasites, recently emerged as very promising because of their piezoelectric properties superior to quartz. This thesis discusses the growth of langasite-type La3Ga5.5Ta0.5O14 (LGT) films by liquid phase epitaxy (LPE) technique and their chemical and structural characterization. In addition, the different techniques suitable for the growth of LGT are discussed and compared. To adjust the materials properties for given applications, doping by selected ions can be used. However, the dopants must be homogeneously distributed. In the current study, Al, Ti, Cr and Ca were investigated as dopants. In an earlier study, Al and Ti had been chosen because of their ability to substitute the octahedral site of LGT, normally occupied by Ga (CN=VI) with a segregation coefficient near unity in Czochralski growth. Doping with Ca and Cr has never been reported before, and therefore, the segregation behavior was unknown. In this study, Al, Ti and co-doping with Cr and Ca has been investigated for both X and Y-oriented films. The dopant distribution in the films was quantitatively evaluated by Secondary Ion Mass Spectroscopy (SIMS), using ion-implanted LGT substrates as standards. The drop of dopant concentration, in the SIMS profile, allows for the identification of the film-substrate interface and to accurately measure the thickness of the films. The film thickness is found to be typically of the order 0.5 to 2µm, depending on growth conditions. The solvent was found a reliable choice, as solvent ions were not incorporated in the films above the detection limits of the characterization techniques. A lead oxide solvent system is used as a solvent for the growth of LGT LPE films with different orientations. Extensive structural characterization was performed. The crystallinity of substrates and films grown with different orientations was compared by X-ray diffraction (XRD). The films show a very high structural perfection, with typically FWHM values of 0.035 for the (004) reflection of the XRD rocking curve. The films were also characterized by TEM. The optical transmittance of the films was characterized by Varian optical spectrophotometer, and the value obtained of approximately 80% is comparable with the transmittance value of the Czochralski grown polished substrate.M.S.M.S.E.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Materials Science & Engr MSMSE
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Krsmanovic, Dalibor. "High temperature ultrasonic gas flow sensor based on lead free piezoelectric material." Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/245065.
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The review of current technologies for measurement of gas velocity in stack flow applications is undertaken and it is shown that the ultrasonic time-of-flight method is the most suitable and offers a number of advantages over alternatives. Weakness of current piezoelectric based transducers are identified as the inability to operate at temperatures above 400 °C due to limitation of piezoelectric materials used, and a case for development of an alternative high temperature material is put forward. A novel and highly enhanced, lead free piezoelectric material, suitable for continuous operation at temperatures above 400 °C has been engineered for ultrasonic gas velocity sensor applications. Structural modification of pure bismuth titanate (Bi4Ti3O12) or BIT compound, through multi-doping at the Ti-site, has been found to enhance piezoelectric properties accompanied with a mild reduction in Curie temperature, Tc. Initially, compounds doped with tungsten and chromium were found to increase the piezoelectric coefficient (d33) from around 5 pC N¯¹ in pure bismuth titanate, to above 20 pC N¯¹ in doped compounds. This increase is attributed to lower conductivity and improved poling conditions. Further increases in d33 (up to 35 pC N¯¹) were then realised through controlled grain growth and reduction in conductivity for niobium, tantalum and antimony doped compounds. The Curie temperature of the material with best properties is found to be 667 °C, which is a slight reduction from 675 °C for pure bismuth titanate ceramic. The enhancements in modified bismuth titanate achieved in present work allow the material to be considered as suitable for high temperature ultrasonic transducer applications. Integration of bismuth titanate material into a working high temperature transducer is then considered and the investigation of suitable, high temperature bonding method is undertaken. It is shown that reactivity of bismuth titanate with the titanium based fillers makes brazing unsuitable as a bonding method between piezo-ceramics and stainless steel. A novel assembly method, using liquid gallium as an electrically conductive bond, and a mechanical restraint for the piezo actuator is then presented as an alternative with the potential to reduce the negative effects of differences in thermal expansion coefficients between constituents of the transducer assembly.
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Sinha, Dhiraj. "Radio frequency magnetic field detection using piezoelectric material incorporating a microcantilever amplifier." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611229.
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Santhanakrishna, Anand Kumar. "Piezoelectric ZnO Nanowires as a Tunable Interface Material for Opto-Electronic Applications." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7926.
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Organic electronic devices are sustainable alternatives to the conventional electronics, due to their advantages of low cost, mechanical flexibility and wide range of applications. With the myriad list of organic materials available today, the opportunities to imagine new innovative devices are immense. Organic electronic devices such as OLEDs (organic light emitting diode), OPVs (Organic photovoltaics) and OFETs (organic field effect transistors) are among the leading device categories. Although OLED’s have been a huge commercial success, other categories are not lagging.
Radical thinking is necessary to improve on the current performances of these devices. One such thinking is to combine the versatile ZnO (Zinc Oxide) material to organic semiconductors. This can be achieved by exploiting the dual nature of ZnO’s semiconducting and piezoelectric property. Many devices have used ZnO in combination with organic semiconductors for applications ranging from sensors, photovoltaics, OFET’s, memory and many others. The goal of the work is to incorporate the piezoelectric nature of hydrothermally grown ZnO nanowires for Opto-electronic applications.
Although the initial research work was done on incorporating the piezo effect of bulk grown ZnO nanowires in improving the efficiency of an OPV, we discovered a unique memory effect in this device by incorporating ZnO nanowires in an inverted organic photovoltaic architecture. The device switched between a rectifying response in dark to resistive behavior under illumination with a finite transition time and was reversible. Since then we decided to explore few of the opto-electronic applications of this technology.
The synthesis and characterization of crystalline ZnO nanowires, nanoforest and planar ZnO nanofilm are reported along with the application of these ZnO nanostructures in optoelectronic devices. Noncentro symmetry of crystalline ZnO nanostructures makes it an excellent candidate to be used as piezo functional material and these nanostructures are characterized using electrochemical cell containing ZnO electrode as the working electrode.
ZnO nanostructures like nanowires, nanoforest and planar nanofilm are similarly characterized for piezo property using electrochemical technique. Different devices require distinguishing physical and electrical properties of ZnO nanostructures, hence morphology, effect of pre-strain, surface area, surface coverage and thickness of these nanostructures were evaluated for its piezoresponse. It is shown that it was possible to obtain similar piezoresponse among different ZnO nanostructures in addition to taking advantage of the structural benefits among various categories of nanostructures as per requirement.
The presented research can be used as the proof-of-the-concept that ZnO nanostructures can be designed and fabricated with a prestrain to adjust the piezo response of the material under external forces. Therefore, the structure with the prestrain can be employed in various electronic and optical devices where the piezo voltage can be used for adjusting the energy band bending at an interface.
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Man, Hou Michael Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "Implicit coupled constitutive relations and an energy-based method for material modelling." Publisher:University of New South Wales. Mechanical & Manufacturing Engineering, 2009. http://handle.unsw.edu.au/1959.4/43652.
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The contributions of this thesis are an implicit modelling method for the coupled constitutive relations and an energy-based method for material modelling. The two developed methods utilise implicit models to represent material constitutive relations without the requirement of physical parameters. The first method is developed to model coupled constitutive relations using state-space representation with neural networks. State-space representation is employed to express the desired relations in a compact fashion while simultaneously providing the capability of modelling rate- and/or path-dependent behaviour. The employment of neural networks with the generalised state-space representation results in a single implicit model that can be adapted for a broad range of constitutive behaviours. The performance and applicability of the method are highlighted through the applications for various constitutive behaviour of piezoelectric materials, including the effects of hysteresis and cyclic degradation. An energy-based method is subsequently developed for implicit constitutive modelling by utilising the energy principle on a deformed continuum. Two formulations of the proposed method are developed for the modelling of materials with varying nature in directional properties. The first formulation is based on an implicit strain energy density function, represented by a neural network with strain invariants as input, to derive the desired stress-strain relations. The second formulation consists of the derivation of an energy-based performance function for training a neural network that represents the stress-strain relations. The requirement of deriving stress is eliminated in both formulations and this facilitates the use of advanced experimental setup, such as multi-axial load tests or non-standard specimens, to produce the most information for constitutive modelling from a single experiment. A series of numerical studies -- including validation problems and practical cases with actual experimental setup -- have been conducted, the results of which demonstrate the applicability and effectiveness of the proposed method for constitutive modelling on a continuum basis.
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Song, Hyun-Cheol. "Piezoelectric-based Multi-Scale Multi-Environment Energy Harvesting." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/87400.
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Energy harvesting is a technology for generating electrical power from ambient or wasted energy. It has been investigated extensively as a means of powering small electronic devices. The recent proliferation of devices with ultra-low power consumption - devices such as RF transmitters, sensors, and integrated chipsets - has created new opportunities for energy harvesters. There is a variety of ambient energies such as vibration, thermal, solar, stray current, etc. Depending on energy sources, different kinds of energy conversion mechanism should be employed. For energy harvesters to become practical, their energy conversion efficiency must improve. This efficiency depends upon advances in two areas: the system or structural design of the energy harvester, and the properties of the materials employed in energy conversion. This dissertation explores developments in both areas. In the first area, the role of nano-, micro-, and bulk structure of the energy conversion materials were investigated. In the second area, piezoelectric energy harvesters and a magneto-thermoelectric generator are treated from the perspective of system design.
In the area of materials development, PbTiO3 (PTO) nanostructures consisting of nanofibers and three-dimensional (3-D) nanostructure arrays were hydrothermally synthesized. The growth mechanism of the PTO nanofibers and 3-D nanostructures were investigated experimentally and theoretically. The PTO nanostructures were composed of oriented PTO crystals with high tetragonality; these arrays could be promising candidates for nanogenerators.
Different designs for energy harvesters were explored as a means of improving energy conversion efficiency. Piezoelectric energy harvesters were designed and constructed for applications with a low frequency vibrational energy and for applications with a broadband energy spectrum. A spiral MEMS piezoelectric energy harvester design was fabricated using a silicon MEMS process and demonstrated to extract high power density at ultra-low resonance frequencies and low acceleration conditions. For a broadband energy harvester, a magnetically-coupled array of oscillators was designed and built that broadened the harvester's effective resonance frequency with considerably improved output power.
A new design concept for thermal energy harvesting that employs a magneto-thermoelectric generator (MTG) design was proposed. The MTG exploits a thermally-induced second order phase transition in a soft magnetic material near the Curie temperature. The MTG harvested electric power from oscillations of the soft magnet between hot and cold sources. For the MTG design, suitable soft magnetic materials were selected and developed using La0.85Sr0.15MnO3-Ni0.6Cu0.2Zn0.2Fe2O4 magnetic composites. The MTG was fabricated from a PVDF cantilever and a gadolinium (Gd) soft magnetic material. The feasibility of the design for harvesting energy from the waste heat was demonstrated by attaching an MTG array to a computer CPU.PHD
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Fujino, Shigehiro. "Combinatorial discovery of a morphotropic phase boundary in a lead-free piezoelectric material." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8554.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Material Science and Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Tremaine, Kellie Michelle. "MODAL ANALYSIS OF COMPOSITE STRUCTURES WITH DAMPING MATERIAL." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/823.
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The purpose of this study is to develop an analytical solution for modal analysis of actively damped orthotropic composite plates in bending and to verify it with experimental analysis.
The analytical modal analysis solution for composite plate dynamics is derived using Euler theory. This analysis applies to structures with orthotropic lamina of uniform material properties at any lamination angle. The bending-extensional coupling can be neglected for plates that are symmetric or approximately symmetric, which allows an exact solution for natural frequency and mode shape to be obtained. An exact solution can be found for natural vibration and in general.
The active control is modeled analytically by combining the Lagrange equation with the Ritz Assumed Mode method. This analysis produces a generalized coordinate vector that correlates the assumed mode to the particular amplitude of a particular case. The kinetic energy dissipated by the piezoelectric actuator from the system over one oscillation can be calculated from the generalized coordinate vector and the assumed mode. The equivalent damping ratio of the active control system is calculated as the ratio between the kinetic energy absorbed by the piezoelectric actuator from the system in one oscillation and the maximum strain energy of the system during that oscillation.
A point mass on the plate, such as an accelerometer mass, can also be modeled as a single layer of uniform mass, that is an isotropic layer, by equating the potential energy of the point mass with the potential energy of the uniform mass layer. It is important to note that the mass of the isotropic layer is frequency dependent, and it has no effect on the plate stiffness.
The analytical model is validated by comparison to experimental work. The samples studied were aluminum and composite plates of various lengths. The active control predictions were also validated using previous experimental work completed at California Polytechnic State University in San Luis Obispo. These cases included active control of an aluminum beam with a patch of piezoelectric material and an aluminum sailplane with a patch of piezoelectric material.
Results indicate that while the analytical mode solutions are in good agreement with the experimental results, they are also systematically higher than the experimental results. The analytical active control solutions match previous work when the piezoelectric effects are linear. The main result of adding an active control system is approximately a 5-10% increase in modal frequencies and a 200-800% increase of damping ratio.
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KANDELL, BRIAN M. "PIEZOELECTRIC POLYMER (PVDF) RIBBON FOR CHOCHLEAR IMPLANTATION - GUIDELINES AND COMPARISONS WITH TOOTHBRUSH STYLE PROTOTYPES." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1141311212.
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Brockmann, Tobias H. "Theory of adaptive fiber composites from piezoelectric material behavior to dynamics of rotating structures." Dordrecht Heidelberg London New York, NY Springer, 2009. http://d-nb.info/997517948/34.
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Lagoin, Thiago Galbiati. "Utilização de materiais piezelétricos (PZTS) para coleta e armazenamento de energia /." Ilha Solteira : [s.n.], 2011. http://hdl.handle.net/11449/94516.
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Orientador: João Antonio PereiraBanca: Walter Katsumi Sakamoto
Banca: Giuliano Pierre Estevam
Resumo: As vibrações mecânicas tem se mostrado uma forma efetiva de geração de energia através da deformação de materiais piezelétricos ou movimentação de bobinas eletromagnética. As técnicas de energy harvesting estudam o processo de extração e armazenamento deste tipo de energia até um nível utilizável. Neste caso que a estrutura piezelétrica é deformada devido à condição de operação gerando uma tensão/corrente que pode ser usada como uma fonte natural de energia, principalmente, para operar dispositivos eletrônicos de baixa potência. Entretanto, a energia gerada através do efeito piezelétrico usualmente não é suficiente para operar diretamente a maioria dos circuitos eletrônicos. Assim, o desenvolvimento e implementação de métodos para acumular e armazenar a energia capturada nestes sistemas (materiais inteligentes) até um nível utilizável é a chave para o sucesso desta tecnologia. Este trabalho discute o estudo e avaliação da modelagem teórica-experimental de uma estrutura do tipo viga com PZTs submetida à deformação causada por vibrações mecânicas, buscando avaliar o comportamento do acoplamento eletromecânico do sistema bem como quantificar a eficiência, não só da quantidade de energia gerada pelo material, mas também o seu armazenamento em dispositivos do tipo capacitor. A modelagem da estrutura piezelétrica foi realizada por elementos finitos com o programa ANSYS e validada com testes experimentais. Em seguida foi feito um estudo paramétrico das variáveis do modelo através de um conjunto de simulações numéricas efetuadas para avaliar o potencial elétrico gerado. Para finalizar foram realizados testes experimentais de dois circuitos eletrônicos utilizados para extrair energia de um material piezelétrico
Abstract: Mechanical vibrations have been shown an effective form of generating energy through deforming piezoelectric materials or moving electromagnetic coil. The energy harvesting techniques studies the processes of extracting and storing this kind of energy until an usable level. In the case that piezoelectric structure is deformed due operation condition it generates a voltage/current that can be used like a natural source of energy, mainly, for operating electronic devices of low power. However, the energy generated through piezoelectric effect usually is not enough to operate directly the most electronic circuits. Therefore, the development and implementation of methods to accumulate and store the energy captured in these systems (smart materials) until an usable level is the key for the success of this technology. This work discusses the study and evaluation of a theoretical-experimental modeling of a beam structure with bounded PZTs submitted to mechanical vibration, aiming at evaluating the behavior of the electro-mechanical coupling of the system, as well as, to quantify the amount of energy generated by the material and the storage of this energy in a capacitive type device. The modeling of piezostructure was performed by finites elements with the program ANSYS and validated with experimental tests. Then a parametric study of model variables was made through a set of numerical simulations carried out to evaluate the electrical potential generated. For finished were performed experimental tests of two electronic circuits used to extract energy from a piezoelectric material
Mestre
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Tahiraj, Klein. "Piezoelectric force microscopy study on zinc tin oxide nanowires." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19405/.
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Self-powered sensor devices could find widespread application to monitor personal health, automobiles or buildings. One of the most ubiquitous form of energy on which these devices could rely is vibrational energy. To convert this energy into electrical energy, the research is focusing on piezoelectric materials. Examples of these materials are ZnO or Zinc Tin Oxides (ZTO). Modelled into nanowires and incorporated into an elastomer at the University of Lisbon, these materials have been demonstrated to result in macroscopically efficient energy conversion. In this work, I use Piezoelectric Force Microscopy to characterize the piezoelectric response of a single ZTO nanowire, namely, to measure the component d33 of its piezoelectric strain tensor. P(VDF-TrFE) thin film, i.e. a material with well characterized piezoelectric proprieties, is used to calibrate the instrument sensitivity. The value I obtain for the d33 of the ZTO nanowire is 23.70±0.04pm/V. In order to use it as a reference, I perform a characterization also for a ZnO nanowire. The value I obtain is 10.36±0.03pm/V. The value for the ZTO nanowire is therefore about double that of the ZnO. This result certifies ZTO nanowires as good candidates for energy conversion in future self-powered devices.
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Lin, Ching-Yu 1972. "Material characterization and modeling for piezoelectric actuation and power generation under high electromechanical driving levels." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8100.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2002.Includes bibliographical references (p. 257-262).
High electromechanical loads parallel to piezoelectric polarization might result in depolarization of the material, depending on the material property itself and the external excitations such as electrical field, electrical driving frequency, stress and stress duration. In this work, material properties under these effects were first characterized experimentally. The experiments included monitoring general piezoelectric responses of PZT-5H and PZT-5A subjected to large electric excitations (butterfly curves) under various static compressions and measuring generalized piezoelectric constants under short and open circuit conditions for actuation of PZT-5A and power generation of PZT-5H, single crystals PZN-PT, and single crystals PMN-PT. To model these observed material behaviors, one- and three-dimensional rate dependent nonlinear constitutive models based on thermodynamic potentials for PZT-5H and PZT-5A piezoelectric materials were then developed. An internal variable, net remnant polarization D*, was used to simulate the hysteric behaviors of piezoelectric materials. An evolution law of D* was derived to specify the rate dependent responses of the materials. The parameters of the material models were determined by minimizing the error between the data and the models. The material models were capable of describing the responses subjected to large electric excitations under static compression, but incapable of predicting accurate piezoelectric constants under dynamic compression. This flaw was believed due to the absence of stress rate dependency in the models. It was also found that the PZT-5A model performed worse than the PZT-5H model because of its highly hysteretic strain-polarization relation.
(cont.) This hysteresis could be explained by the slow switching rate of 90-degree domain movement. Finally, to simulate devices under non-uniform field or with irregular geometries using these material models, differential algebraic equations for mixed finite element analysis of 3-D nonlinear rate dependent piezoelectric materials were formulated and solved numerically by DASPK solver. Using 4-node tetrahedral elements, this formulation was demonstrated by examples with uniform and skewed electric excitations. The combination of the nonlinear mixed FEM model and the material model provided a useful tool for modeling the response of active devices with complicated geometries and irregular boundary conditions.
by Ching-Yu Lin.
Ph.D.
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輝心, 黄. "Three-scale structure analysis and thin film generation of a new biocompatible piezoelectric material MgSiO3." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB12252687/?lang=0, 2011. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB12252687/?lang=0.
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Procházka, Josef. "MKP model piezoelektrických MEMS filtrů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231204.
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This thesis focuses on simulation modelling of a piezoelectric MEMS filter, which may be used as a part of cochlear implant. A model of this filter is created in the programme ANSYS. A research on experimental cochlear implants and materials suitable for this application is also included.
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Rabčan, Jakub. "Analýza využití SMART materiálů jako aktivních prvků pro snímáni vibrací." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-402504.
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This diploma thesis deals with the possibility of vibration sensing and vibrodiagnostics based on the use of so-called "SMART" materials such as piezoelectric layers or structures. Research studies have examined the general overview of vibrodiagnostic methods and their analysis of the possibility of sensing vibration by piezoelectric structures. This was followed by measuring and evaluating the results using various vibro-diagnostic methods. The results were compared with those obtained by sensing vibration using an accelerometer. We also dealt with the problem of detecting the deformation of the device by sensing vibration with piezoelectric structures. The last part was programming the "Myrio" to capture and evaluate the vibration using Labview.
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Lagoin, Thiago Galbiati [UNESP]. "Utilização de materiais piezelétricos (PZTS) para coleta e armazenamento de energia." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/94516.
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As vibrações mecânicas tem se mostrado uma forma efetiva de geração de energia através da deformação de materiais piezelétricos ou movimentação de bobinas eletromagnética. As técnicas de energy harvesting estudam o processo de extração e armazenamento deste tipo de energia até um nível utilizável. Neste caso que a estrutura piezelétrica é deformada devido à condição de operação gerando uma tensão/corrente que pode ser usada como uma fonte natural de energia, principalmente, para operar dispositivos eletrônicos de baixa potência. Entretanto, a energia gerada através do efeito piezelétrico usualmente não é suficiente para operar diretamente a maioria dos circuitos eletrônicos. Assim, o desenvolvimento e implementação de métodos para acumular e armazenar a energia capturada nestes sistemas (materiais inteligentes) até um nível utilizável é a chave para o sucesso desta tecnologia. Este trabalho discute o estudo e avaliação da modelagem teórica-experimental de uma estrutura do tipo viga com PZTs submetida à deformação causada por vibrações mecânicas, buscando avaliar o comportamento do acoplamento eletromecânico do sistema bem como quantificar a eficiência, não só da quantidade de energia gerada pelo material, mas também o seu armazenamento em dispositivos do tipo capacitor. A modelagem da estrutura piezelétrica foi realizada por elementos finitos com o programa ANSYS e validada com testes experimentais. Em seguida foi feito um estudo paramétrico das variáveis do modelo através de um conjunto de simulações numéricas efetuadas para avaliar o potencial elétrico gerado. Para finalizar foram realizados testes experimentais de dois circuitos eletrônicos utilizados para extrair energia de um material piezelétrico
Mechanical vibrations have been shown an effective form of generating energy through deforming piezoelectric materials or moving electromagnetic coil. The energy harvesting techniques studies the processes of extracting and storing this kind of energy until an usable level. In the case that piezoelectric structure is deformed due operation condition it generates a voltage/current that can be used like a natural source of energy, mainly, for operating electronic devices of low power. However, the energy generated through piezoelectric effect usually is not enough to operate directly the most electronic circuits. Therefore, the development and implementation of methods to accumulate and store the energy captured in these systems (smart materials) until an usable level is the key for the success of this technology. This work discusses the study and evaluation of a theoretical-experimental modeling of a beam structure with bounded PZTs submitted to mechanical vibration, aiming at evaluating the behavior of the electro-mechanical coupling of the system, as well as, to quantify the amount of energy generated by the material and the storage of this energy in a capacitive type device. The modeling of piezostructure was performed by finites elements with the program ANSYS and validated with experimental tests. Then a parametric study of model variables was made through a set of numerical simulations carried out to evaluate the electrical potential generated. For finished were performed experimental tests of two electronic circuits used to extract energy from a piezoelectric material
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Lee, Jae Sang. "Effective properties of three-phase electro-magneto-elastic multifunctional composite materials." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/1448.
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Coupling between the electric field, magnetic field, and strain of composite materials is achieved when electro-elastic (piezoelectric) and magneto-elastic (piezomagnetic) particles are joined by an elastic matrix. Although the matrix is neither piezoelectric nor piezomagnetic, the strain field in the matrix couples the E field of the piezoelectric phase to the B field of the piezomagnetic phase. This three-phase electro-magneto-elastic composite should have greater ductility and formability than a two-phase composite in which E and B are coupled by directly bonding two ceramic materials with no compliant matrix. A finite element analysis and homogenization of a representative volume element is performed to determine the effective electric, magnetic, mechanical, and coupled-field properties of an elastic (epoxy) matrix reinforced with piezoelectric and piezomagnetic fibers as functions of the phase volume fractions, the fiber (or particle) shapes, the fiber arrangements in the unit cell, and the fiber material properties with special emphasis on the symmetry properties of the fibers and the poling directions of the piezoelectric and piezomagnetic fibers. The effective magnetoelectric moduli of this three-phase composite are, however, less than the effective magnetoelectric coefficients of a two-phase piezoelectric/piezomagnetic composite, because the epoxy matrix is not stiff enough to transfer significant strains between the piezomagnetic and piezoelectric fibers.
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Brockmann, Tobias H. [Verfasser]. "Theory of adaptive fiber composites : from piezoelectric material behavior to dynamics of rotating structures / Tobias H. Brockmann." Dordrecht, 2009. http://d-nb.info/997517948/34.
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Shatalov, MY, AC Every, and AS Yenwong-Fai. "Analysis of non-axisymmetric wave propagation in a homogeneous piezoelectric solid circular cylinder of transversely isotropic material." Elsevier, 2008. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001768.
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a b s t r a c t
A study concerning the propagation of free non-axisymmetric waves in a homogeneous
piezoelectric cylinder of transversely isotropic material with axial polarization is carried
out on the basis of the linear theory of elasticity and linear electro-mechanical coupling.
The solution of the three dimensional equations of motion and quasi-electrostatic equation
is given in terms of seven mechanical and three electric potentials. The characteristic equations
are obtained by the application of the mechanical and two types of electric boundary
conditions at the surface of the piezoelectric cylinder. A novel method of displaying dispersion
curves is described in the paper and the resulting dispersion curves are presented for
propagating and evanescent waves for PZT-4 and PZT-7A piezoelectric ceramics for circumferential
wave numbers m = 1, 2, and 3. It is observed that the dispersion curves are sensitive
to the type of the imposed boundary conditions as well as to the measure of the
electro-mechanical coupling of the material.
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Yang, Xiaomei, and 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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Chee, Clinton Yat Kuan. "STATIC SHAPE CONTROL OF LAMINATED COMPOSITE PLATE SMART STRUCTURE USING PIEZOELECTRIC ACTUATORS �." University of Sydney. Aeronautical Engineering, 2000. http://hdl.handle.net/2123/709.
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The application of static shape control was investigated in this thesis particularly for a composite plate configuration using piezoelectric actuators. A new electro-mechanically coupled mathematical model was developed for the analysis and is based on a third order displacement field coupled with a layerwise electric potential concept. This formulation, TODL, is then implemented into a finite element program. The mathematical model represents an improvement over existing formulations used to model intelligent structures using piezoelectric materials as actuators and sensors. The reason is TODL does not only account for the electro-mechanical coupling within the adaptive material, it also accounts for the full structural coupling in the entire structure due to the piezoelectric material being attached to the host structure. The other significant improvement of TODL is that it is applicable to structures which are relatively thick whereas existing models are based on thin beam / plate theories. Consequently, transverse shearing effects are automatically accounted for in TODL and unlike first order shear deformation theories, shear correction factors are not required. The second major section of this thesis uses the TODL formulation in static shape control. Shape control is defined here as the determination of shape control parameters, including actuation voltage and actuator orientation configuration, such that the structure that is activated using these parameters will conform as close as possible to the desired shape. Several shape control strategies and consequently algorithms were developed here. Initial investigations in shape control has revealed many interesting issues which have been used in later investigations to improve shape controllability and also led to the development of improved algorithms. For instance, the use of discrete actuator patches has led to greater shape controllability and the use of slopes and curvatures as additional control criteria have resulted in significant reduction in internal stresses. The significance of optimizing actuator orientation and its relation to piezoelectric anisotropy in improving shape controllability has also been presented. Thus the major facets of shape control has been brought together and the algorithms developed here represent a comprehensive strategy to perform static shape control.
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Luan, Jiyuan. "Design and Development of High-Frequency Switching Amplifiers Used for Smart Material Actuators With Current Mode Control." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36914.
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This thesis presents the design and development of
two switching amplifiers used to drive the so-called
smart material actuators. Different from conventional
circuits, a smart material actuator is ordinarily a
highly capacitive load. Its capacitance is non-linear
and its strain is hysteretic with respect to its
electrical control signal. This actuator's reactive
load property usually causes a large portion of reactive
power circulating between the power amplifier and the
driven actuator, thus reduces the circuit efficiency
in a linear power amplifier scenario. In this thesis,
a switching amplifier design based on the PWM technique
is proposed to develop a highly efficient power
amplifier, and peak current mode control is proposed
to reduce the actuator's hysteretic behavior. Since
the low frequency current loop gain tends to be low
due to the circuit's capacitive load, average current
mode control is further proposed to boost the low
frequency current loop gain and improve the amplifier's
low frequency performance. Both of the circuits have
been verified by prototype design and their experimental
measurement results are given.Master of Science
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Cervelin, José Eduardo. "Redução de vibrações mecânicas em processos de torneamento usando material piezelétrico." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18156/tde-16062014-135146/.
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Vibrações mecânicas oferecem grande limitação para a produtividade, qualidade ou mesmo viabilidade das operações de usinagem, especialmente quando se trata das autoexcitadas (chatter). Neste trabalho, foram desenvolvidas estratégias que tem como objetivo diminuir a intensidade de vibrações em processos de torneamento por meio do acoplamento de material piezelétrico ao suporte de ferramenta em conjunto com uso de shunts resistivo, indutivo e resistivo-indutivo em série ou em paralelo, criando assim estruturas eletromecânicas passivamente amortecidas. Para tanto, foram construídos modelos eletromecânicos de parâmetros distribuídos para mostrar a capacidade que tais estruturas eletromecânicas possuem em oferecer um maior amortecimento quando comparadas com estruturas mecânicas convencionais. Com os modelos construídos, foi possível verificar a influência causada pela espessura da camada de material piezelétrico bem como a influência dos shunts no comportamento da estrutura, sendo constatado que camadas mais espessas aumentam a capacidade de amortecimento da estrutura e que os shunts resistivo-indutivo, tanto em série quanto em paralelo, funcionam como um amortecedor dinâmico de vibrações amortecido e oferecem o melhor desempenho. A seguir, construiu-se o diagrama de lóbulos de estabilidade para comparar as estruturas com e sem shunts e observou-se que as estruturas com shunts resistivo-indutivo possuem um melhor desempenho. Também foram executados testes de impacto (tap tests) para a verificação experimental do comportamento da estrutura quando conectadas aos shunts e os resultados mostraram que há um maior amortecimento. Considerando os resultados obtidos, acredita-se que seja possível melhorar o desempenho de processos de torneamento usando material piezelétrico.Mechanical vibrations offer great limitation for the productivity, quality or even feasibility of the machining operations when chatter is present. In this work it was developed strategies aiming to diminish the intensity of the vibration in turning processes. By coupling a piezoelectric material with a turning tool and by using different associations of resistive and inductive shunt (series or parallel) it was created electromechanical structures passively damped. Electromechanical models of distributed parameters were developed in order to show the capacity that these structures has to offer a greater dumping when compared with conventional mechanical structures. By using these constructed models it was possible to verify the influence of the thickness of the piezoelectric material as well as the influence of shunts in the behavior of structure. It was observed that thicker layers increase the damping capacity of the structure that resistive-inductive shunt (series or parallel) works as a damped dynamic vibration absorber which offer better performance. Latter was developed a stability lobes diagram in order to compare the structures with and without shunts and it was observed that structures connected to resistiveinductive shunt has a better performance. Tap tests were performed for the purpose of study the experimental behavior of the structure connected to shunt and results showed that there is a better damping in this situation. Considering the results obtained, is fair to believe that is possible to improve turning process by using piezoelectric materials.
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Cicogna, Thiago Rodrigo. "Identificação de matrizes de função de resposta em freqüência multidirecionais em estruturas complexas." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-19012011-142931/.
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Este trabalho apresenta o desenvolvimento de uma metodologia para a estimativa de funções de resposta em freqüência angulares (FRFAs). Trata-se de uma técnica que utiliza transdutores piezelétricos (PZT) do tipo bimorph para a medição da curvatura local da estrutura através do potencial elétrico induzido pela extensão e compressão do sensor. A partir da estimativa da curvatura, a rotação pode ser obtida diretamente através de várias técnicas de interpolação (polinomial, formas modais, etc). Apresenta-se a modelagem téorica da qual se deriva as equações que governam a dinâmica de estruturas uni-dimensionais, do tipo viga, e estruturas bidimensionais, do tipo placa, ambas isotrópicas, onde se incorpora o sensor bimorph. Modelos em elementos finitos foram propostos no intuito de avaliar a utilização destes sensores (bimorphs) aplicados à estimativa das FRFAs. Apresentam-se também resultados numéricos e experimentais considerando-se uma viga engastada-livre (cantilever) e resultados numéricos considerando-se uma placa simplesmente apoiada. Um algoritmo genético foi ainda desenvolvido no intuito de determinar a posição e dimensão ótimas dos bimorphs em estruturas do tipo viga.The present work aims to perform the development of an attractive approach for accurate measurement of angular frequency response functions (AFRFs). It uses bimorph piezoceramic patches to measure the structure\'s local curvature through the measurement of the electric potential induced by the extension and compression of the patch\'s top and bottom stripes, respectively. From this curvature, rotation can be obtained directly by several interpolation techniques (single polynomial, modes basis). Theoretical modeling of the vibration incorporating piezoelectric bimorph sensor is presented and equations governing the dynamics for one-dimensional structures, like a beam, and for two-dimensional structures, like a plate, are derived for isotropic structures. Finite element model for the dynamic analysis were proposed to evaluate bimorphs patches applied to the measurement of angular FRFs. Numerical and experimental results are presented considering a cantilever beam and numerical results for a simply supported plate as tested structured. Also, in this work, a genetic algorithm was used as an adaptive heuristic search algorithm for optimal placement and sizing of the bimorph sensor into beam like structures.
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Lacour, Olivier. "Influence de la piézoélectricité sur l'absorption du son dans les milieux composites." Grenoble 1, 1989. http://www.theses.fr/1989GRE10058.
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Headings, Leon Mark. "Modeling, characterization, and design of smart material driven stick-slip actuation mechanisms." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1141700440.
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Junior, Rubens Martins Cunha. "Otimização das propriedades estruturais de filmes de nitreto de alumínio visando sua aplicação como material piezoelétrico." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-20072016-153016/.
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Neste trabalho é apresentado um estudo sobre a produção e caracterização do nitreto de alumínio (AlN) obtido pela técnica de r.f. Magnetron Sputtering reativo. Aqui reportamos o efeito dos parâmetros de deposição, como densidade de potência de r.f., temperatura e pressão de processo nas propriedades estruturais, morfológicas e elétricas dos filmes de AlN obtidos. Foram realizados estudos sobre os modos vibracionais, pela técnica de espectroscopia de infravermelho por transformada de Fourier (FTIR), das orientações cristalográficas por difração de raios X e da morfologia da superfície pela técnica de microscopia de força atômica (AFM). Estes estudos nos permitiram produzir filmes finos de AlN com uma alta orientação na direção cristalográfica [002] com uma potência de r.f. de 1,23 W/cm2 , uma temperatura de deposição de 200°C e uma pressão de processo de 2 mTorr. Este estudo nos permitiu fabricar filmes de AlN com alta orientação [002] à temperatura ambiente a partir de um alvo de Al. O coeficiente piezoelétrico d33 variou de aproximadamente 4 a 6 pm/V e o d31 2 a 3 pm/V para filmes cristalinos e d33 3 pm/V e d31 1,5 pm/V para filmes amorfos. Os coeficientes piezoelétricos d33 and d31 foram estimados pelo método capacitivo proposto por Mahmoud Al Ahmad and Robert Plana, através da variação das dimensões geométricas induzidas pelo campo elétrico aplicado.In this work we present a study about the production and characterization of aluminum nitride (AlN) obtained by r.f. Reactive Magnetron Sputtering. Here we report the effect of the deposition parameters, such as r.f. power density, and deposition temperature and pressure, on the morphological, structural and electrical properties of the obtained AlN thin films. In this work we have performed studies concerning the vibrational modes by Fourier Transform Infrared Absorption technique (FTIR), the crystallographic orientations by X-ray diffraction and the surface morphology by Atomic Force Microscopy (AFM). This study allowed us to produce high oriented [002] AlN thin films with a r.f. power density of 1.23 W/cm2, a deposition temperature of 200ºC and a process pressure of 2 mTorr. This study allowed us to produce high oriented [002] AlN thin films at room temperature from a pure Al target. The piezoelectric coefficient d33 was around 4 to 6 pm/V and d31 2 to 3 pm/V to crystalline films and d33 3 pm/V and d31 1.5 pm/V amorphous ones. d33 and d31 piezoelectric coefficients were estimated by the capacitive method proposed by Mahmoud Al Ahmad and Robert Plana, through its geometrical dimensions variation.
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Huang, Tai-Rong, and 黃泰榮. "Anisotropic Material Constants Measuring of Additive Manufactured Materials and Piezoelectric Ceramics." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/87378396047866671729.
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碩士國立臺灣科技大學
機械工程系
103
This study used on the fused deposition modeling of 3D printer to process the specimens of three different directions. The specimens with different additive manufacture were measured their mechanical properties by static and the dynamic tests. The specimens of static test under the simply-supported beam boundary condition load the weight in the middle of specimens so that the Young's modulus were determined by measuring the deformation of strength. The specimens of dynamic test were achieved by the boundary condition of cantilever beam. Using a steel ball to strike the cantilever beam, the transient signal were obtained by two measured methods. Through the piezoelectric film bounded on the cantilever beam, the dynamic strain were determined by oscillator connecting with charge amplifier. Through the laser Doppler vibrometer (LDV) to measure the non-contact optical signals, the velocity were determined by the LDV built-in modulator. Using Fast Fourier Transform (FFT) to transfer the transient signals in time domain as frequency domain, the resonant frequency can be indicated by the maxima of frequency spectrums. Finally, the Young's modulus, Poisson’s ratio, and shear modulus can be calculated according to the theory of Bernoulli-Euler beam. Finally, the orthotropic material constants of the additive manufacturing specimen can be built by those static and dynamic tests. The material constants of piezoelectric ceramics, which are developed on the piezoelectric print head development of 3D stereolithographic printer, are determined by resonance method according to IEEE standard. First, the commercial piezoelectric print head was dissemble in order to realize its components of the structure. Because dynamic characteristics of piezoelectric device need to establish by finite element calculation, the anisotropic material constants of piezoelectric materials were determined using in design of piezoelectric print head. The resonant frequencies obtained from FEM results, which were calculated by importing the anisotropic material constants of piezoelectric ceramics, were verified by two kinds of experimental measurements. The resonant frequencies and mode shapes both of out-of-plane and in-plane vibrations were determined by electronic speckle pattern interferometry (ESPI) and the in-plane resonant frequencies were also measured by impedance analyzer. The vibration characteristics of piezoelectric ceramics are shown in good consistence between FEM results and experimental measurements.
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Chen, Pin Hong, and 陳品宏. "Research on piezoelectric material product module system." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/85502496110192229693.
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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
98
This paper aims at the experimental study on the force-electricity conversion system made of the piezoelectric material (PM). Two types of the PZT piezoelectric material, including Md and Ka, were used and a PM power generators were designed and made. The efficiency of the PM power generator was tested. In the experiments, four pieces of the PM with parallel connection were tested to investigate the efficiency of the PM power generation module system under various compressive loading. Each type of the PM (Md and Ka) was set up with three different layers so that their thickness differed, where 2±0.1mm, 4±0.1mm, and 6±0.1mm were corresponding to 1, 2, and 3 layers, respectively. The regression analysis of testing results reveal that when the PM power generation module system subjecting 100kgf compressive loading with 0.05Hz load frequency, and the thickness increased from 1, 2, to 3 layers, the Md type PM would generate the power with voltages of 9.53, 15.97, and 22.01Volts, respectively. Under the same condition, the results of the Ka type PM power generation module were 10.74, 19.4, and 24.3Volts, respectively. The results also show that the power generation efficiency of PM will increase as the load increased. The power generation efficiency of raw PM is supposed to use at 1000Hz loading frequency. In this study, the PM was tested under low frequency loading condition, range from 0.05Hz~0.75Hz. The experimental result shows that the power generation efficiency will reduce 50% in low frequency when compared to raw PM at high frequency.
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Kim, Justin Young-Hyun. "Parylene-C as a New Piezoelectric Material." Thesis, 2013. https://thesis.library.caltech.edu/7705/9/Thesis_2013_EE_Justin%20Young-Hyun%20Kim_final.pdf.
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The goal of this thesis is to develop a proper microelectromechanical systems (MEMS) process to manufacture piezoelectric Parylene-C (PA-C), which is famous for its chemical inertness, mechanical and thermal properties and electrical insulation. Furthermore, piezoelectric PA-C is used to build miniature, inexpensive, non-biased piezoelectric microphones.
These piezoelectric PA-C MEMS microphones are to be used in any application where a conventional piezoelectric and electret microphone can be used, such as in cell phones and hearing aids. However, they have the advantage of a simplified fabrication process compared with existing technology. In addition, as a piezoelectric polymer, PA-C has varieties of applications due to its low dielectric constant, low elastic stiffness, low density, high voltage sensitivity, high temperature stability and low acoustic and mechanical impedance. Furthermore, PA-C is an FDA approved biocompatible material and is able to maintain operate at a high temperature.
To accomplish piezoelectric PA-C, a MEMS-compatible poling technology has been developed. The PA-C film is poled by applying electrical field during heating. The piezoelectric coefficient, -3.75pC/N, is obtained without film stretching.
The millimeter-scale piezoelectric PA-C microphone is fabricated with an in-plane spiral arrangement of two electrodes. The dynamic range is from less than 30 dB to above 110 dB SPL (referenced 20 µPa) and the open-circuit sensitivities are from 0.001 – 0.11 mV/Pa over a frequency range of 1 - 10 kHz. The total harmonic distortion of the device is less than 20% at 110 dB SPL and 1 kHz.
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Tsay, Meng-chien, and 蔡孟倩. "Application of Piezoelectric Material in Structural Vibration Analysis." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/49120456339457962423.
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碩士正修科技大學
營建工程研究所
96
This study is to probe the Piezoelectric material apply to the structure and shake feasibility analysis on, caused by that bear the external force the response of shaking because of the structure, will influence the demands of structurl safefy and serviceabitity. So vibration amount examines the antivibration to the structure thing, is a very important with the vibration investigation and analysis of present . This thesis, by striking impact hammer and vibration platform imitating and load to the structure , emergency rule and shifting to count vibration to reflect the detecting device, shake the feasible analysis of the characteristic experiment, theory mechanics analysis and experimental analysis, analyse via the three the result of incomes carries on models and proves, confirm limited element model and exactness and suitability of the theory model. And then utilize the piezoelectricity material equivalent examining device to relatively verify the result, examine the suitability and feasibility of the method for the amount of experiment confirmed.
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Chen, Yi-Chen, and 陳怡臻. "Application of opto-piezoelectric material in valveless micropump." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/63815015601130403128.
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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
102
In this work, we intended to change the dynamic flow rate of valveless micropump by developing a new smart composite material which is able to construct an actuator that can spatially modulated by optical means. The smart opto-piezo composite material is composed of photoconductive material TiOPc and piezoelectric material PZT. Spatial optical modulation in an opto-piezo composite mentioned above means modulating a force field of the actuator by changing the light field instead of changing the spatial distribution of the electrical field. To enhance the effect of modulating a force field by using the light field, the electrical impedance of TiOPc/copolymer thin film was measured by Agilent 4294A Precision Impedance Analyzer to investigate the impedance and electrical characteristics change before and after the external light illumination. We analyzed the relationship between the parameters of driving bias, frequency and diffuser angle so as to compare the flow rate difference of valveless micropump after illumination. According to the experimental results of flow rate of valveless micropump, the maximum flow rate was 95.33μL/min under the condition of driving bias 100V, frequency 600Hz and diffuser angle 10°. Furthermore, the maximum flow rate of optical-modulated valveless micropump increased from 6.09μL/min to 19.62μL/min, and the ability of spatial dynamic flow rate modulation was confirmed by illuminated different area of valveless micropump. Coupling these preliminary results with some future works, return flow typically associated with the valveless micropump can potentially be further reduced in the future.
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Chiang, Yen-Ching, and 江彥青. "Environment-Friendly Lead-Free Piezoelectric Material Business Plan." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/53332671553011011808.
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碩士國立交通大學
企業管理碩士學程
98
This study is to perform feasibility evaluation of an actual lead-free piezoelectric bismuth ferrite (BiFeO3) which developed by NCTU in Taiwan has great potential as an efficient replacement for traditional PZT (lead zirconate titanate) in business plan format. There are several alternatives of PZT (lead zirconate titanate), but they are more expensive or less efficient than it. Thus, PZT (lead zirconate titanate) are most widely used to manufacture products in the modern world. However, PZT (lead zirconate titanate) is a lead-based. Lead has classified as a hazardous substance because of its negative environmental and health effects. Therefore, global environmental concern, government policy such as RoHS and WEEE , and market potential drive companies, universities, colleges, research institutions to discover a practical lead-free piezoelectric material to substitute PZT (lead zirconate titanate). The environment-friendly lead-free piezoelectric bismuth ferrite (BiFeO3) generates 12% more electricity than traditional PZT and has similar production cost. To win over a complicated scenario and commercialize the core technology successfully, the research uses the business plan format to identify the market opportunity, define marketing as well as operation strategy and make risk assessment and 5-years-period financial analysis to help the entrepreneurs and companies to obtain and maintain the sustainable competitive advantages. Through practical and valuable literature re-views, strategy market research, industry and academic experts’ interviews, real business negotiations, and participating in international entrepreneur competitions, the business plan is enhanced more practically and completely, which really generates important and practical findings for the next business stage.
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Cleveland, Michael Allen. "Multifunctional Composites and Devices for Sensing and Energy Harvesting." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-05-7902.
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This research investigates a novel class of active materials for energy and sensing applications. Magnetocaloric alloys, Gd5Si2Ge2, were developed into a composite with poly(vinylidine flouride) (PVDF), piezoelectric polymer. The giant megnetocaloric property combined with the piezoelectricity creates extraordinary properties for composite materials.
The research approach was primarily experimental. Activities include synthesis, characterization, and device design and evaluation. Using the arc melting method, the magenetocaloric samples were created. Multi-length scales characterized using atomic force microscopy (AFM), optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-Ray diffraction (XRD), and X-Ray Photoelectron spectroscopy (XPS). The prototype devices were evaluated for their power generation and efficiency. Through those techniques, the fundamental understanding in the new materials was obtained. The relationships between process-microstructures, microstructure-properties, and structure-power generation were established.
Results showed that the phase transformation of the magnetocaloric material at its Curie temperature induced a significant increase in power generation in the peizeoelectric polymer. Such transition was also beneficial for a laminated device for energy harvesting. In addition, it was found that the oxidation that occurred during high temperature melting stabilized the orthorhombic phase at room temperature. The multifunctional composites as well as the laminated structure use the thermal expansion of the magnetocaloric material for energy harvesting, cyclic monitoring, and/or thermal switching.
This thesis consists of six chapters. Chapter I provides a history and explanation of the materials used. Chapter II provides an explanation of the motivation for this work. Chapter III addresses the experimental procedures. The results of which are presented in Chapter IV and discussed in Chapter V. The research is summarized and future recommendations are given in Chapter VI.
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Tsai, Wen-Chih, and 蔡汶志. "Material Characterization of Piezoelectric Fiber Composites under Periodic Electrodes." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/70192168882225989190.
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碩士國立交通大學
機械工程系所
96
Piezoelectric fiber composite (PFC) actuated by symmetrically aligned interdigital electrodes on its opposite surfaces is an emerging smart material developed in recent years. The PFC is capable of providing large deformation and stiff exciting force. The flexibility of PFC makes it possible to conform to curved surfaces of the host structures. These properties make PFC possess great potential to become a functional material in applications of structural health monitoring, aerospace structures, etc. The effective material constants of PFC are estimated by rule of mixtures. Some material constants, s33, s13 and d33 , d31 , are directly measured by stain gauges through uniaxial tensile test and applying high voltage to its opposite electrodes. The remaining constants are determined by an inverse scheme based on quasi-Newton method. The quadratic objective function is defined by the sum of squares of deviations between the measured resonant frequencies of the lowest extensional vibration modes for the finite-length overhung PFC and those calculated by a commercial finite element code ANSYS. It is observed by a polar light microscope that the piezoelectric fibers and interdigital electrodes are not uniformly aligned in some specimens. The deviation found in measured material constants is caused by the inhomogeneous material properties. The piezoelectric constant d15 is not suitable to be determined by the present method since it has weak influence on resonant frequency of extensional mode and divergent properties in seneitivity study of parameters. Most material constants are in agreement with those obtained by effective model estimated by mixture rule.
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Qiu, Jin Dong, and 邱進東. "Optimal control of light structure by using piezoelectric material." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/03826693245325215847.
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Lai, Hua-Chien, and 賴華謙. "Study of Timoshenko Beam With Partly Embedded Piezoelectric Material." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/15592568562775181387.
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碩士國立成功大學
工程科學系碩博士班
95
In this paper, Finite element method and analytic method is employed to study vibration control of Timoshenko beam with partly embedded piezoelectric material. To compare with the modal frequencies calculated by the two methods, the finite element solutions are approached to the analytic solutions. In vibration analysis and vibration control, the actuator provide a damping by coupling a negative velocity feedback control algorithm in a closed control loop. Use Newmark method to compute the dynamic response of entire beam. The results of gain effects, embedded displace effects and embedded length effects can good increse the suppression of vibration.
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Su, Yu Cheng, and 蘇裕盛. "Computation of stress intensity factor for crack in piezoelectric material." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/32555372548942449893.
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碩士國立成功大學
機械工程學系
86
In this study Conservative-Integral is used to solve stress intensity fact ors which is near the crack tip field in piezoelectric material. We superimpos e the unknown field which we wish to know and the auxial field which is a know n asymptotic crack tip singularity solution and get a superimposed field. Then we use the concern of the three fields to get interaction energy release rate . And we use finite element method as the numerical method to compute the inte raction energy release rate which is the type of domain integral. It is also c alled Interaction integral. So the stress intensity factor can be geted of the unknown field when we determined the stress intensity factor of the auxial fi eld. In this paper we consider a two-dimensional homogeneous piezoelectric material problem with a crack lied on the x-axis. The direction of pored axis in this case is perpendicular to the crack plane. The last we can get reasonab le results of stress intensity factor when the material subjected far field me chanical load and electric load.
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Chen, Yu-Hsien, and 陳又賢. "The Three-Dimension Vibration Sensor Design Using A Piezoelectric Material." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/09005473408082081981.
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碩士逢甲大學
自動控制工程研究所
84
Abstraction The vibration measurements play an important role in industry and laboratory. To get suitable sensors for accurate vibration measurements are desired. One- dimension vibration sensors have been developed well but they have intrinsic interfenence problems. This thesis is proposed to design the piezoelecric-type sensors for the three-dimension vibration measurements. The PVDF（polyvinylidene fluoride） material was used as the vibration sensing material. The bases of sensors are designed to enhance vibration signal but to reduce noise. The vibration sensing systems were tested using the Vibration Simulation System series 9363-SR (King Design Co.). According to the reponse data, the three-dimension vibration sensor has good linearity in the operation range from 200Hz to 400Hz. For the whole tested frequency range (100Hz-600 Hz), the output curves show reasonable linearity. Comparing with the non-axial response, the main-axial sensor response is much strong, so the system parasitic noise can be ignored. Keywords：piezoelectric material, vibration sensor, vibration measurement
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Chuang, Ming-Hua, and 莊明樺. "Handling Experimentals for Mini-Walking Machines Made of Piezoelectric Material." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/27448117336391644734.
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Chang, Kai-jei, and 張凱傑. "On Multiple Circular Piezoelectric Inclusions Embedded in an Intelligent Material." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/68195682486451617331.
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HONG, ZONG-HUEI, and 洪宗暉. "Theoretical Analyze for the Antiplane Problem of a Piezoelectric Material." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/73088534383251668744.
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碩士南臺科技大學
機械工程系
104
The theoretical analysis for the antiplane problem of a piezoelectric material subjected to a point loading had been investigated by the technique of the Fourier transform, image method and conformal mapping in the study. The geometric configuration of the piezoelectric body includes the infinite plane, half-plane, bimaterial consisting of two half plane, quarter plane, bimaterial consisting of two quarter plane, single layer and composited layer. The point loading consists of the antiplane shear force, screw dislocation, concentrated charge, and voltage. The boundary conditions include mechanical boundary such as traction and displacement and electric boundary as electric charge and voltage. Based on the analytical solutions, the influence of boundary conditions on the field of displacement, stress, electric displacement, and electricity will be discussed. The properties of the image method for antiplane piezoelectric material will be known in detail as well. Use the conformal mapping to obtain the solution of a layered media from quarter plane will be illustrated in the paper. The numerical calculation with practical piezoelectric ceramics will be presented in figures in the study. These figures will be used to verify the correctness of analytical solutions obtained in the study and explain the distribution of physical fields for the piezoelectric ceramics.
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Chang, Sheng-Hsin, and 張聖心. "Quantitative Determination of Material Viscoelasticity Using a Piezoelectric Cantilever Bimorph Beam." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/33995489889870125728.
Full textAbstract:
碩士國立高雄第一科技大學
機械與自動化工程所
90
The objective of this paper is to formulate the governing equation of a cantilever bimorph beam associated with a tip mass in contact with a viscoelastic material, which is modeled by a stiffness and a damper in parallel. From the eigenvalue problem, we can obtain the resonant frequencies as functions of the tip mass and material stiffness. The relation between the spectrum and material damping is established by the half-power bandwidth. It is found that the resonant frequencies increase as the material stiffness increases or the tip mass decreases, and the spectrum decreases by increasing the damping. From the analytic results, a cantilever could provide a technique to assess material viscoelasticity by simple measurements of the resonant frequency and the spectrum. Since the cantilever’s behavior scales with its geometry, the device can be designed specifically for mechanical measurement of a microscopic system such as living cells and biomaterials.