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Preparation and characterization of epoxy potting resins modified with nanoparticles
Lednický, Jiří ; Polsterová, Helena (referee) ; Chladil, Ladislav (advisor)
This bachelor's thesis focuses on nanocomposites composed of an organic matrix in the form of epoxy resin and TiO2 filler in the anatase crystallographic structure with dimensions in the order of tens of nanometers. The work is aimed at understanding the issue of nanocomposites, summarizing the results of other studies, and especially at the production and characterization of samples with nanoparticles dispersed using a planetary mill. Furthermore, the effect of the used nanoparticles and dispersion in the planetary mill on the dielectric properties of pure epoxy resin was analyzed.
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Circular Representative Volume Element for Homogenization of Discrete Model of Concrete
Středulová, Monika ; Eliáš, Jan
The contribution presents initial results obtained by employing a circular representative volume element (RVE) for the homogenization of a discrete model of concrete. Based on initial research, circular RVE might be a promising alternative to the classical square one (for 2D problems), especially considering its use in conjunction with periodic boundary conditions after strain localization in the material. The contribution shows the behaviour of the circular RVE in elastic loading and compares it to the results obtained by the usually used square RVE.
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Banach Algebras
Machovičová, Tatiana ; Nechvátal, Luděk (referee) ; Franců, Jan (advisor)
By Banach algebra we mean Banach space enriched with a multiplication operation. It is a mathematical structure that is used in the non-periodic homogenization of composite materials. The theory of classical homogenization studies materials assuming the periodicity of the structure. For real materials, the assumption of a periodicity is not enough and is replaced by the so-called an abstract hypothesis based on a concept composed mainly of the spectrum of Banach algebra and Sigma convergence. This theory was introduced in 2004.
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Homogenization in Perforated Domains
Rozehnalová, Petra ; Bock, Igor (referee) ; Rohan, Eduard (referee) ; Franců, Jan (advisor)
Numerické řešení matematických modelů popisujících chování materiálů s jemnou strukturou (kompozitní materiály, jemně perforované materiály, atp.) obvykle vyžaduje velký výpočetní výkon. Proto se při numerickém modelování původní materiál nahrazuje ekvivalentním materiálem homogenním. V této práci je k nalezení homogenizovaného materiálu použita dvojškálová konvergence založena na tzv. rozvinovacím operátoru (anglicky unfolding operator). Tento operátor poprvé použil J. Casado-Díaz. V disertační práci je operátor definován jiným způsobem, než jak uvádí původní autor. To dovoluje pro něj dokázat některé nové vlastnosti. Analogicky je definován operátor pro funkce definované na perforovaných oblastech a jsou dokázány jeho vlastnosti. Na závěr je rozvinovací operátor použit k nalezení homogenizovaného řešení speciální skupiny diferenciálních problémů s integrální okrajovou podmínkou. Odvozené homogenizované řešení je ilustrováno na numerických experimentech.
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Homogenization of closed foam structures using Kelvin cell
Škoviera, Jozef ; Navrátil, Petr (referee) ; Skalka, Petr (advisor)
The bachelor‘s thesis deals with creating calculation model of the foam structure based on Kelvin cell with closed porosity. First aim of this work is homogenization of the foam structure by identical deformation response in foam structure and continuum. Second aim is follow-up parametrical study of influence of characteristic measures of Kelvin cell on material characteristics. Task was solved in ANSYS software by method of final elements. Resultant dependences rendering was done in MATLAB software.
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Sample preparation for DNA analysis from foods of plant origin
Silná, Renata ; Rittich, Bohuslav (referee) ; Kovařík, Aleš (advisor)
The isolation of high quality DNA is nessecary for many molecular biology applications. However, plant DNA contains high amonts of polysaccharides, polyphenols and various secondary metabolites, which decrease yield and quality of isolated DNA. The aim of this study was preparation of samples and different food matrices for DNA isolation DNA by magnetic particles. It was about 5 species of vegetable and 10 species of processed plant food. Homogenization of samples was performed in CTAB buffer. Isolation of plant DNA was performed by magnetic particles covered with carboxyl groups. All DNAs were isolated in conventional PCR qualities using primers for 700 bp amplicons, in the case of heat processed products for 220 bp ampilicons and for real time PCR. The efficiancy of separation of magnetic particles with DNA by magnetic separator and magnetic needle was compared. It was find out that DNA of higher purity was isolated using magnetic needle. The micromethod of isolation of plant DNA from homogenates with CTAB with magnetic particles is suitable for different processed food.
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Design of the composite rotor sleeve of a high speed rotary machine
Pavlík, Ondřej ; Ševeček, Oldřich (referee) ; Návrat, Tomáš (advisor)
The diploma thesis focuses on manufacturing carbon fiber and epoxy composite material using filament winding method. Material properties of manufactured composite are ap-proximated using analytical and numerical homogenization models. Calculated material properties are applied to design and evaluate reserve factor of retaining sleeve for high speed brushless permanent magnet synchronous motor. Margin of safety of designed rotor is evaluated using composite failure criteria. Test stand for both static and dynamic testing is designed, static test stand is manufactured and assembled. Static strength test is carried out.
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News in the field of the road construction
Zelenka, Lukáš ; Zajíček, Jan (referee) ; Varaus, Michal (advisor)
The bachelor’s thesis focuses on new technological equipment for transport and paving of asphalt mixtures. Specifically, it is a thermo superstructure with an extrusion face and a homogenization tank of an asphalt mixture. The advantages of these machines and their positive influence on the quality of the work are described. Subsequently, the researches which confirm it are described. The last chapter describes recommendations for the contracting authority to require the use of these technologies in tenders.
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Lattice Topology Optimization in ANSYS software
Černák, Martin ; Vaverka, Ondřej (referee) ; Vrána, Radek (advisor)
ANSYS is one of the first commercially available software which allows to make topology optimization of lattice structures. In this bachelor’s thesis optimization workflow, calibration of numerical model, validation of numerical results and revelation of influence of basic parameters involved in computation – cell type, minimum and maximum relative density, cell size and used discretization, are showed. Optimised part was compared by means of FEM and homogenization with available experimental data. Subsequently, influence of basic parameters was evaluated. It was shown that optimized structure is stiffer than benchmark and influence of basic parameters for mechanical response and computational complexity was introduced. Simultaneously, it was shown that homogenization overestimated mechanical response. The findings of bachelor’s thesis validate computational model in program ANSYS and can be used for more effective making of optimization models.
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CFD modelling of pipe flow mixing of liquids
Pavlíček, David ; Hájek, Jiří (referee) ; Juřena, Tomáš (advisor)
This work is focused on computational modelling of mixing fluids in pipeline with static mixers. Main objective is to analyze several selected static mixers in a particular industrial application, namely dosing of the aluminium sulphate solution in the clarification process for potable water treatment. The analysis focuses on the degree of mixedness and pressure loss of individual mixers. Further, the aim of this work is to process the search of available types of static mixers. The benefit of this work is at least an effort to motivate the reader to deeper understanding of the mixing fluids, especially by static mixers.
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