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MEMS based energy harvesting
Klempa, Jaroslav ; Prášek, Jan (referee) ; Gablech, Imrich (advisor)
This work is dedicated to principles of energy harvesting or scavenging from free energy around us. Energy harvesting principles are described in the first part. Following chapter is devoted to description of piezoelectricity and piezoelectric materials. Next part researches already reported results on piezoelectric energy harvesters. Following chapter shows simulations on designed structures in ANSYS® Workbench. Next the fabrication of the structures is described. Measurement are made regarding to maximum generated power.
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Evaluation of Fracture Mechanical Parameters for Bi-Piezo-Material Notch
Hrstka, Miroslav ; Materna, Aleš (referee) ; Náhlík, Luboš (referee) ; Profant, Tomáš (advisor)
Předkládaná dizertační práce se zabývá stanovením hlavních členů Williamsova asymptotického rozvoje popisujícího rovinné elektro-elastické pole v okolí piezoelektrických bi-materiálových vrubů a trhlin na rozhraní za použití rozšířeného Lechnického-Eshelbyho-Strohova formalismu v návaznosti na čistě anizotropní pružnost. Je ukázáno, že rozšířený Lechnického-Eshelbyho-Strohův formalismus představuje spolu s moderními programovacími koncepty v jazyku Python efektivní a také praktický nástroj pro lomovou analýzu piezoelektrických bi-materiálů. Teoretická část práce popisuje aspekty anizotropní pružnosti a její návaznost na piezoelektrické materiály. Základní rovnice zaměřené na speciální typy monoklinických materiálů, které umožňují oddělení rovinného a anti-rovinného problému, jsou vyjádřeny pomocí komplexních potenciálů. V praktické části práce je sestaven problém vlastního hodnot pro bi-materiálový vrub, na jehož základě jsou stanoveny exponenty singularity a pomocí dvoustavového -integrálu také zobecněné faktory intenzity napětí. Veškeré vztahy a numerické procedury jsou následně rozšířeny na problém piezoelektrických bi-materiálových vrubů a podrobně prozkoumány v uvedených příkladech. Zvláštní pozornost je věnována přechodu asymptotického řešení téměř zavřených vrubů a trhlin na rozhraní. Vliv směru polarizace na asymptotické řešení je také zkoumán. Přesnost stanovení zobecněných faktorů intenzity napětí je testována srovnáním asymptotického řešení a řešení získaného pomocí metody konečných prvků s velmi jemnou sítí konečných prvků. Na závěr je formalismus modifikován pro nepiezoelektrické materiály.
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Piezoelectric MEMS resonators for sensing applications
Klempa, Jaroslav ; Svatoš, Vojtěch (referee) ; Gablech, Imrich (advisor)
Basic principles and processes used during fabrication of microelectromechanical systems are presented in this work. This thesis is focused on material properties, deposition, lithographic and micromachining processes. Fundamental principles and applications of piezoelectric resonant structures are described as well. Final part of this work is devoted to simulation of resonant beams using FEM method in ANSYS® Workbench, practical fabrication and characterization of piezoelectric MEMS resonators.
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Estimation of equivalent circuit parameters of a piezoelectric resonator
Ryšavý, Lukáš ; Majzner, Jiří (referee) ; Sedlák, Petr (advisor)
In this thesis, a simple measurement setup including control software is designed to estimate the parameters of Mason electrical equivalent circuit for piezoelectric resonators. Direct measurements can evaluate variables, such as mechanical quality factor, parallel resonance, serial resonance and serial resistance. These variables are used to estimate remaining parameters. The software is implemented in C++ Builder. Experimental study and verification were carried out on several quartz crystal and piezoceramic samples. The measurements are in good agreement with simulations as it is illustrated by a low value of relative error. The measurement setup will be used for scientific purposes of Dept. of physics FEEC BUT.
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Using of Piezo-material for Energy Harvesting from Vibration
Hanus, Jiří ; Dušek, Daniel (referee) ; Hadaš, Zdeněk (advisor)
Master’s Thesis deals with obtaining electricity from the vibrations of the surrounding environment through piezoelectric vibration generator. To simulation piezoceramics and design mechanical parts of the generator was used simulation program ANSYS 10.0. First, parameters of the designed piezoelectric generator were numerically calculated, and then these values were compared with the real sample. Further work is in the description of material properties of piezo materials.
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Measurment of Equivalent Circuit of Piezoelectric Resonator
Vomočil, Vojtěch ; Frk, Martin (referee) ; Kazelle, Jiří (advisor)
This theis deals with the general overview of the piezoelectric theory, focused both on the mathematical description and on the attributes of piezoelectric materials. It further focuses on the description of piezoelectric resonators with a more detailed explantation of their equivalent scheme and measurement methods of its single elements. The practical part of the thesis rests on the proposal of a measurement apparatus which will serve to measuring the equivalent circuit piezoelectric resonator elements. The realization of the apparatus and its functionality testing are described. In the experimental part of the thesis, the measured rates are processed and levels of the electric equivalent circuit elements of the used piesoelectric resonator for the basic and the two higher closest resonance frequency are set. The measured results are compiled into a standard measurement protocol. This thesis should place basics to the growing laboratory. It should also be a source of necessary theoretical and practical information for this lab.
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Proposal of piezo-generator inside button
Kučera, David ; Houška, Pavel (referee) ; Hadaš, Zdeněk (advisor)
This bachelor’s thesis deals with proposal of piezo-generator inside button. There are described types of piezo-generators, explained piezoelectric effect, types of piezoelectric material with focus on piezoceramics. The properties of piezoelectric ceramics are described. Proposal of piezo-generator inside button is described at the end of this thesis.
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Preparation of nanoforms of layered piezoelectric of systems BI2O3-TA(2)O(5)-AO (A=CA,SR,BA)
Štarman, S. ; Matz, V. ; Kváča, Z. ; Mohyla, M. ; Olšák, V. ; Plocek, Jiří ; Vaněk, Přemysl ; Tylš, B.
Based on the known Aurivillius phases types ABi2Ta2O9 and A2BiTaO6 ( A=Ca, Sr, Ba) were supplemented with new compositions of layered tantalates, which resulted the possibility of the existence of a new phase Sr2BiTaO6. Ternary compounds with piezoelectric structure were prepared as nanoforms by solgel reactions of homogeneous acetate Bi, Ta, A and subsequent annealing in a controlled atmosphere. Annealing temperature was determined from DSC curves based on the weight loss and phase transitions. Composition and structure of nanocrystals has been analyzed by X-ray diffraction (XRD), scanning nanomorphology (SEM) and acoustic measurements.
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