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Computer modelling of mixture formulas of composite materials
Matoušek, Jiří ; Frk, Martin (referee) ; Rozsívalová, Zdenka (advisor)
Submitted work engage in modelling of progressions of dielectric variables and aplication of mixture formulas for solution of composite materials in dependency on frequency. Theoretical part engage in theory of dielectric materials and composite materials and contains summary of basic mixture formulas. A part of work is programm which can be used in education. It allows modelling of permitivity, loss factor and loss number in dependency on frequency and Cole-Cole circle diagram in materials. In mixtures modelling of Maxwell´s, Bőttcher´s and Lichtenecker´s mixture formulas.
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Optimalisation of coposite materials for civil engineering
Kazda, Tomáš ; Chladil, Ladislav (referee) ; Novák, Vítězslav (advisor)
This work is focused on optimalisation of coposite materials for civil engineering. In the theoretical part of the project is introduction of the composite materials and materials which are used for their production. There are also concerned their properties and possible application areas. In conclusion of theoretical part this project is a summary of the possible use of composite materials. The practical part compares the characteristics of the different types of composites made in terms of conductivity and the rate of corrosion.
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Modelling and behaviour of composite systems in AC electric field
Matoušek, Jiří ; Frk, Martin (referee) ; Rozsívalová, Zdenka (advisor)
This work deals with modeling of progression of dielectric variables and mixture formulas for solution of properties of composite materials in dependency on frequency. Theoretical part of the work explains physical principles of polarisation mechanisms and influence on dielectric constant with changing temperature and frequency. In theoretical part processes inside the composite material, which is in electrical field are described. The work contains summary of mixture formulas and methods of their derivation. Program for use in education is a part of the work. It allows modelling of progression of dielectric variables in dependency on frequency and Cole-Cole circle diagram. In mixtures it allows modelling of frequency dependencies of dielectric constant in accordance to Maxwell's, Bőttcher's and Lichtenecker's mixture formulas.
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Neural networks for EMC modeling of small airplanes
Koudelka, Vlastimil ; Goňa,, Stanislav (referee) ; Raida, Zbyněk (advisor)
This thesis deals with neural modeling of electromagnetic field inside small aircrafts, witch can contain composite materials in their construction. Introduction to neural networks and its application in EMC of small airplanes is discussed in the first part of the text. In the second part of this thesis we design a simple EM model of small airplane. The airplane is simulated by two parallel dielectric layers (the left-hand side wall and the right hand side wall of the airplane). The layers are put into a rectangular metallic waveguide terminated by the absorber in order to simulate the illumination of the airplane by the external wave (both of the harmonic nature and pulse one). Numerical analyses are performed to search the relations between the distribution of an electromagnetic field inside the aircraft and electric parameters of model walls. The results of numerical analyses are used to train two types of neural network. In this way we can obtain accurate continuous model of electromagnetic field inside the aircraft. For the comparison with neural networks a multi-dimensional cubic spline interpolation is provided also. Neural classifiers are also investigated. We use them for classification of imaginary composite materials in terms of EMC. The nearest neighbour algorithm is applied as a classic approach to problem of classification.
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Plasmochemical treatment of natural fibres
Demková, Eva ; Mazánková, Věra (referee) ; Přikryl, Radek (advisor)
This bachelor thesis is focused on plasmochemical surface treatment of natural flax fibres using dielectric barrier discharge and silane coupling agent. Treated fibres were used as reinforcement of composite material with an epoxy matrix. Composite materials were prepared manually, by placing saturated fibres into silicone mold. Mechanical properties of composite materials were determined by bending test, tensile test and dynamic-mechanical analysis (DMA). The presence of a silane coupling agent on the surface of the fibre was detected by EDS analysis. SEM method was also used to determine the effect of plasma on the surface of fibres.
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Lightweight composites based on fluid filter ashes
Palovčík, Jakub ; Másilko, Jiří (referee) ; Opravil, Tomáš (advisor)
This Bachelor’s thesis deals with preparation, study and analysis of binders based on fluid filter ashes. Binders were doped with various additives to alter the rheological properties, reduce volumetric weight and increase flexural compressive and tensile strength. Next, a possibility of using waste polyester fibres for reinforcement in matrices based on above mentioned binders was determined. The prepared samples were tested for compression and flexural strength after 28 days. Phase composition was analysed by means of X-ray diffraction analysis.
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The mechanical properties of fiber reinforcement laminates
Jílek, Jan ; Němec, Karel (referee) ; Válka, Libor (advisor)
This bachelor's thesis summarizes the current findings in the area of evaluation of mechanical properties of fibre reinforcement laminates. In the thesis an algorithm for acquiring material characteristics of laminate by calculation is introduced, the results are tested by tensile stress. Among the calculated and experimental values of material characteristics only a small difference was found. The effect of temperature on stiffening of laminate on mechanical properties is studied.
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Experimental comparison of shear properties of FRP measured by ASTM methods
Ponížil, Tomáš ; Mališ, Michal (referee) ; Urík, Tomáš (advisor)
Přesné určení konstitutivních smykových závislostí napětí na deformacích je základem pro pochopení chování anizotropního kompozitního materiálu. Bylo vyvinuto mnoho zkoušek smykových vlastností kompozitních materiálu. Jelikož vyvolání čisté smykové napjatosti je složité, tento stav je vyvolán pouze některými z nich. V této práci je ověřeno použití systému Aramis k vyhodnocení průběhu smykového přetvoření a následnému výpočtu konstitutivních smykových vlastností při provedení jednoduché zkoušky ohybem krátkého nosníku. Tyto výsledky jsou dále porovnány se zkouškou podle Nicolae Iosipesca.
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