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Inteligentní materiály v letectví
Riger, Rostislav ; Jetela, Václav (oponent) ; Klement, Josef (vedoucí práce)
Tato bakalářská práce se zabývá inteligentními materiály a jejich aplikacemi v letectví. V teoretické části je vysvětleno, co rozumíme pod pojmem inteligentní materiály a čeho chceme s jejich použitím dosáhnout. Dále jsou tyto materiály seřazeny podle principu fungování a popsány. V praktické části je práce zaměřena na konkrétní aplikace inteligentních materiálů v letectví. Někdy se jedná pouze o teoretické aplikace, které nebyly ještě použity.
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Koncepce uspořádání pohonné jednotky na letounu
Bauer, Martin ; Klement, Josef (oponent) ; Píštěk, Antonín (vedoucí práce)
Tato bakalářská práce se zabývá koncepcemi umístění pohonných jednotek na letounech. Je zde vytvořen přehled uspořádání pohonných jednotek v jednotlivých kategoriích letounů. V práci jsou uvedeny výhody a nevýhody různých řešení z hlediska aerodynamického, pevnostního, konstrukčního, výkonnostního, provozního a bezpečnostního.
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Možnosti použití motorů koncepce Propfan v letecké dopravě
Polák, Andrej ; Klement, Josef (oponent) ; Šplíchal, Miroslav (vedoucí práce)
Bakalářská práce je psaná rešeršní formou a pojednává o leteckých motorech koncepce propfan. Po představení samotné koncepce se první část zabývá principem fungování motorů a jejich propulsní účinností. Druhá část stručně popisuje konstrukci těchto motorů se zaměřením na specifické části odlišující motory koncepce propfan od ostatních leteckých motorů. Následně jsou shrnuty vlastnosti těchto motorů, popsány jejich výhody a nevýhody spolu s moţnostmi eliminace nevýhod. Nakonec je stručně popsána historie vývoje koncepce propfan.
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DESIGN, STRESS ANALYSES AND LIMIT LOAD OF SANDWICH STRUCTURES
Löffelmann, František ; Pavlínek,, Vladimír (oponent) ; Klement, Josef (oponent) ; Píštěk, Antonín (vedoucí práce)
The thesis starts with a review of design calculations of sandwich beams, plates, and complicated structures, where FEM plays an important role. Next, optimization methods are reviewed to shed light on the wide area of mathematical programming and basic topology optimization principles up to its implementation by other authors in composite design, including representative examples of analytical and numerical optimization of sandwiches. The thesis objective is defined as an implementation of mass minimization with failure constraints aiming to make the sandwich design process easier. This is done by own implementation of gradient optimization based on topology optimization principles, known as Discrete Material Optimization (DMO), which helps to find optimal layup. Approach to material interpolation and failure constraints interpolation is developed and programmed in Python, using First Order Shear Deformation Theory (FSDT) to evaluate stresses on elements, based on element loads given by the Nastran FE solver. Gradient optimizer searches for optimal materials for each layer of the sandwich face-sheet and core from the user-defined candidates. The program is tested on examples of sequential complexity from one-element beams where the true optimum is known up to a practical task of the sandwich galley from an airliner. Results have shown that the algorithm can reach a discrete solution without (significant) violation of constraints and thus can be practically used to make conceptual sandwich design more efficient.
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Hardenability of aluminium alloys and its experimental determination
Weiss, Andrej ; Jetela, Václav (oponent) ; Klement, Josef (vedoucí práce)
The Diploma thesis deals with the verification of Jominy end-quench test when analysis of hardenability of aluminium alloys is considered. The problem was solved experimentally, by developing end-quench curves of selected grades of aluminium alloys. Degree of hardenability of alloy is hardness after complete strengthening heat treatment. Samples of aluminium alloys commonly used for aircraft structures were prepared and then subjected to end-quench tests in various quenchants. On the basis of performed experiments, suitability of Jominy end-quench test for comparison of hardenability of alloys was found. Part of the thesis deals with the creation of equivalent cooling rate diagrams using the developed end-quench curves.
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Diagnostika hydraulických soustav letadel
Bencalík, Karol ; Rousek, Miroslav (oponent) ; Klement, Josef (oponent) ; Třetina, Karel (vedoucí práce)
V letectví se přikládá velký důraz na bezpečnost letecké techniky. Aktuální technický stav letounu a jeho systémů je tedy důležitým parametrem pro jeho letovou způsobilost. Pro určení technického stavu prvku by bylo vhodné srovnání dat měřených za letu s parametry udávanými výrobcem, jež jsou měřeny za provozních podmínek. Disertační práce se zabývá použitím bezrozměrných čísel pro diagnostiku hydrogenerátoru a možnostmi diagnostiky vybraných prvků.
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Fatigue Crack Growth Retardation Techniques for the Integral Airframe Structure
Jetela, Václav ; Růžička, Milan (oponent) ; Petrásek, Miloslav (oponent) ; Klement, Josef (vedoucí práce)
A problem with fast crack propagation arose from utilizing integral airframe structure. One of the techniques to slow down crack propagation and prolong the fatigue life is the application of crack retarder. The aim of this thesis is to compare the performance of additively manufactured crack retarders with bonded ones in terms of the fatigue life, crack growth rate and delamination. In case of the bonded crack retarders; no attention has been paid to the crack retarders made of stainless steel. The stainless steel appears to be a suitable candidate for its coefficient of thermal expansion close to the aluminum, high strength and elastic modulus. Regarding the additively manufactured crack retarders, little or no attention has been paid to the crack retarders made of metals different than the base structure. To address this research gap, two distinctive technologies were selected: cold spray and ultrasonic consolidation. Using the cold spray, the titanium and stainless steel crack retarders were deposited. Using the ultrasonic consolidation, the stainless steel crack retarders were welded. In the experimental work, the crack advance was visually observed. The crack retarder delamination was monitored using the pulsed thermography with subsequent Thermographic Signal Reconstruction. Bonded stainless steel crack retarders proved to be an suitable alternative to the already proven carbon fibre crack retarders. Stainless steel retarders significantly lowered the fatigue crack growth rate which resulted in longer fatigue life. However, all cold sprayed crack retarders accelerated crack growth rate and led to the specimen's premature failure. Ultrasonically consolidated crack retarder with two steel layers was the most effective in the life prolongation. The study also proved, that the delamination in the ultrasonically consolidated metal laminates can be detected using pulsed thermography.
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DESIGN, STRESS ANALYSES AND LIMIT LOAD OF SANDWICH STRUCTURES
Löffelmann, František ; Pavlínek,, Vladimír (oponent) ; Klement, Josef (oponent) ; Píštěk, Antonín (vedoucí práce)
The thesis starts with a review of design calculations of sandwich beams, plates, and complicated structures, where FEM plays an important role. Next, optimization methods are reviewed to shed light on the wide area of mathematical programming and basic topology optimization principles up to its implementation by other authors in composite design, including representative examples of analytical and numerical optimization of sandwiches. The thesis objective is defined as an implementation of mass minimization with failure constraints aiming to make the sandwich design process easier. This is done by own implementation of gradient optimization based on topology optimization principles, known as Discrete Material Optimization (DMO), which helps to find optimal layup. Approach to material interpolation and failure constraints interpolation is developed and programmed in Python, using First Order Shear Deformation Theory (FSDT) to evaluate stresses on elements, based on element loads given by the Nastran FE solver. Gradient optimizer searches for optimal materials for each layer of the sandwich face-sheet and core from the user-defined candidates. The program is tested on examples of sequential complexity from one-element beams where the true optimum is known up to a practical task of the sandwich galley from an airliner. Results have shown that the algorithm can reach a discrete solution without (significant) violation of constraints and thus can be practically used to make conceptual sandwich design more efficient.
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