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Piezoelectricity In Technical Practice
Škarabelová, Lenka
Bachelor's thesis is dedicated to the study of the principle and possibilities of use of the piezoelectric effect. Since the use of piezoelectric effect in electrical engineering is very extensive, the main focus is placed on the ability to exploit this effect in the field of ultrasonic and piezoelectric resonators. Next aim of this work is practically and theoretically to get acquainted with the measurement with an ultrasonic equipment from company Olympus and ultrasonic defectoscopy for detection of possible imperfections in the material and their evaluation.
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Measurement of energy harvesters
Kašpárek, Ondřej ; Pikula, Stanislav (referee) ; Kunz, Jan (advisor)
Over recent years the power outputs of piezoelectric energy harvesters have increased to the point where they rival other types of energy harvesting and therefore their sufficient parameterization is necessary. Four piezoelectric PVDF films - DT1-028KL, DT1-052K, DT2-028K a LDT2-028K made by SENZOR SOLUTIONS TE Connectivity were parametrized by two created systems of measurement with force strain. Power outputs of these films when pressed with harmonic force signal with 3 Nrms amplitude are in nW and transferred energies after force impulse with size 300 N are between hundreds and tenths of fJ. Furthermore, values of quality factor, resonance frequency, optimal load resistance and maximal power stability were determined.
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Electrical characterization of flexible nanofiber piezoelectric materials
Pokorná, Romana ; Holcman, Vladimír (referee) ; Tofel, Pavel (advisor)
This bacherol thesis is focused on piezoelectric nanofibrous materials. The first part describes the formation, use and possible aplications of nanofibers. It further analyze the principle of piezoelectric effect. It is a conversion of mechanical energy into electric energy and conversely. The second part is focused on design of experimental workplace for measurement of functional material properties. The last section of the thesis is dedicated to the electrical characterization of PVDF nanofibers and to the measurement of the piezoelectric charge constant.
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Characterization of lead-free piezoelectric ceramics
Šťastná, Magdaléna ; Holcman, Vladimír (referee) ; Tofel, Pavel (advisor)
This project is focused on lead-free piezoelectric ceramics which are meda in CEITEC. Behaviour of these ceramics is quite different from the lead one. The first part is dedicated to dielectrics and its polarisation techniques. These techniques also include the piezoelectric effect which occurs only in crystals without central symmetry. The following part is focused on piezoelectric materials, piezoelectric polymers and piezoelectric ceramics respectively. The next section of the project is dedicated to the design of an experimental workplace for direct measurement of the piezoelectric charge coefficient đť‘‘33. The experimental part of the work is focused on electric characterisation of lead-free piezoceramics.
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Electrospinning of composite fiberous structures for piezoapplications
Schifferová, Zuzana ; Kaštyl, Jaroslav (referee) ; Částková, Klára (advisor)
Polymer and composite polymer-ceramic nanofibers were prepared by electrospinning process. Solution of 20 wt.% polyvinylidene fluoride (PVDF) in a mixture of dimethyl sulfoxide (DMSO) and acetone in the ratio of 7:3 was chosen as the most suitable precursor. When preparing composite nanofibers, 20 wt.% of barium calcium zirconate titanate (BCZT) or barium titanate (BT) nanoparticles was added to this PVDF solution. Given parameters were defined as the most suitable for the process of electrospinning: voltage of 50 kV, feeding rate of 30 l/min, distance between emitter and collector of 20 cm and needle diameter of 17 G. The effect of polymer molecular weight and the rotation speed of collector was also studied. Various properties of prepared samples were studied: morphology and fiber diameter, phase composition with the use of x-ray diffraction and Fourier transform infrared spectroscopy and also chosen electrical properties. Lower fiber diameters appeared with lower polymer molecular weight and higher rotation speed of the collector. These parameters resulted in higher percentage of the piezoelectric phase as well. The smallest achieved fiber diameter was around 300 nm, the highest percentage of phase was 92 % and the highest piezoelectric constant had a value of 16 pC/N. Composite fibers filled with BT particles showed better properties that the ones filled with BCZT particles.
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Nano-ammeter with galvanic isolation
Šimka, Marek ; Kubíček, Michal (referee) ; Kolka, Zdeněk (advisor)
This bachelor thesis deals with all the aspects, that are important in the designing of the nano-ammeter. In theoretical part, there are described possible ways to measure electrical current of very low values. Other parts of the thesis describe all parameters, which are influencing measurement accuracy. These are, for example, unwanted and leakage currents, but also other parasitic phenomena that may occur. Thesis explains how to minimize unwanted currents and other influences. Practical section provides more detailed description of the proposed main scheme. There are also described components, that have been selected as the main parts of the nano-ammeter circuit. Subsequent part contains analysis of printed circuit board including all layers. Furthermore, the thesis deals with the realization of equipment and possible errors. The results of the bachelor are summarized in the last chapter.
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Analytical model of composite cantilever with SMART layer
Dostal, Vojtěch ; Ševeček, Oldřich (referee) ; Majer, Zdeněk (advisor)
This bachelor's thesis deals with analytical modelling of composite cantilever with smart layer. The structure is based on the real piezoelectric generator, which is a solid cantilever beam with a layer of piezoelectric material attached to its bottom and top. The first part of this bachelor's thesis summarizes the knowledge of the energy harvesting, the process under which harvesting of electric energy from the piezoelectric generator belongs. Some piezoelectric materials are mentioned and described afterwards. At first, analytical modelling is implemented on the homogeneous cantilever beam. Then, the relations for required characteristics are derived for laminate structure, which is structurally similar to the piezoelectric generator. One chosen parameter will be changeable. Due to the ties of relations, the required characteristics will change as well, which are for the piezoelectric generator strain and deflection.
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Piezoelectric vibration energy harvester
Klásek, Matyáš ; Rubeš, Ondřej (referee) ; Hadaš, Zdeněk (advisor)
The first goal of this bachelor’s thesis is to give an overview of piezoelectric materials and their utilization in energy harvesting applications. The second goal is to examine the effect of altering model parameters on generated power and natural frequency of the system using analytical model of a bimorph piezoelectric cantilever beam in MATLAB/Simulink.
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Piezoelectricity in technical practice
Škarabelová, Lenka ; Frk, Martin (referee) ; Kazelle, Jiří (advisor)
Bachelor's thesis is dedicated to the study of the principle and possibilities of use of the piezoelectric effect. Since the use of piezoelectric effect in electrical engineering is very extensive, the main focus is placed on the ability to exploit this effect in the field of ultrasonic and piezoelectric resonators. Next aim of this work is practically and theoretically to get acquainted with the measurement of small changes in weight, using electrochemical quartz crystal microbalance (EQCM), also with an ultrasonic equipment from company Olympus and ultrasonic defectoscopy for detection of possible imperfections in the material and their evaluation.
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Measurement of the piezoelectric charge coefficient
Stehno, David ; Uher, Miroslav (referee) ; Fialka, Jiří (advisor)
The thesis aim was to study in theory the determination of piezoelectric coefficients, in particular piezoelectric coefficient of charge and to use different measurement methods to determine this factor. Also to further study the issue of determining the uncertainties and determine the measurement uncertainty. Measurements were conducted on cylinder-shaped samples, with different dimensions of individual samples. With type material PCM51 and PCM41. Piezoelectric coefficient measurements of charge was carried out using three methods: frequency, direct and quasi-static. The results achieved by all methods are compared at the end of this study and the measurements uncertainty are calculated and discussed for each method.
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