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Design of miniature specimens for calibration of ductile fracture criteria
Salvet, Patrik ; Vobejda, Radek (referee) ; Šebek, František (advisor)
Numerické simulace se v posledních letech s rostoucí výpočetní kapacitou výrazně rozšiřují. Metoda konečných prvků má velký potenciál k tomu, aby částečně nahradila a doplnila experimenty, které jsou drahé, zdlouhavé a často obtížně proveditelné. Jedno z hlavních využití numerických simulací je predikce a simulace chování materiálu. Tato diplomová práce se zabývá kalibrací a porovnáním různých fenomenologických kritérií tvárného porušování závislých na triaxialitě napětí a třetím invariantu tenzoru deviátoru napětí, které lze implementovat do metody konečných prvků k predikci růstu trhliny. Tato kritéria tvárného porušení byla kalibrovaná pro slitinu hliníku 2024-T351 s využitím makroskopických vzorků. Kalibrace byla provedena v MATLABU aproximací kalibračních bodů kritériem tvárného porušování s využitím optimalizační metody hejna částic. Hookův zákon, nový nedávno publikovaný model plasticity a nesvázaný model tvárného porušování kalibrovaný pomocí makroskopických vzorků byly implementovány do Abaqusu/Explicit za účelem navrhnutí čtyř miniaturních vzorků pro již sestrojené zkušební tahové zařízení. Navržené miniaturní vzorky zachycují různé typy napjatosti v místě iniciace trhliny zahrnující jednoosou napjatost, smykovou napjatost a rovinnou deformaci. Kombinací experimentů a numerických simulací těchto vzorků lze provést kalibraci kritérií tvárného porušování za účelem stanovení vhodnosti miniaturních vzorků pro predikci iniciace a šíření tvárného lomu.
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Using simulation to predict defects in and evaluate properties of die-cast Al-alloy castings
Morávková, Jitka ; Nová, Iva (referee) ; Čech, Jaroslav (advisor)
The purpose of this diploma thesis is comparing the quantity of porosity in die-cast aluminium casting with using simulation. The cast engine blocks were made by high pressure die-casting and a local squeeze casting (LSC) technology. There was also examined the relationship between porosity and mechanical properties of castings. There were evaluated and compared the results of my own measurements with data from previous students theses at the Faculty of Mechanical Engineering BUT. All data were tested by statistical tests. The comparison of simulation results and experimentally measured values was found a good programme-ability to simulate and estimate porosity.
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Evaluation of porosity in gravity - cast Al - alloy castings
Staňková, Markéta ; Nová, Iva (referee) ; Čech, Jaroslav (advisor)
Solving of this diploma thesis is evaluation porosity in sequence on mechanical properties from different Al alloys. Castings were made by gravity casting to the iron-mould or gravity casting to the sand. Measurements (mechanical properties, porosity, DAS - dendrite arm spacing, shape factors and sphericity) were statistically analysed and dependencies which were detected were processed to the graphs.
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Al-alloy die-castings for automotive industry
Havel, Jiří ; Nová, Iva (referee) ; Čech, Jaroslav (advisor)
This search is concentrated on Pressure-castings of aluminum alloys for the automotive industry. In the theoretical part of this topic is described in terms of technology for casting aluminum alloys with a focus on high-pressure casting of aluminum alloy AlSi9Cu3 and methods of detecting residual stress. In the experimental section is a sample of residual stress measurements on samples cast alloy AlSi9Cu3.
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Electron beam welding of parts made from aluminium alloy
Jirák, David ; Jakoubek, Jaroslav (referee) ; Daněk, Ladislav (advisor)
The topic of this thesis was ordered by Valeo Compressor Humpolec Itd (further referred to as Valeo). It deals with the electron welding of a component made of an aluminium alloy, a piston specifically, which is made for an automobile air-conditioning compressor. The aim of this thesis was to analyze and suggest a way of increasing porosity of the welded area. The data needed for the analysis and the present state of the welded area was provided by Valeo.
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Semi-solid casting of aluminium alloys
Zelníčková, Marta ; Lána, Ivo (referee) ; Roučka, Jaromír (advisor)
The great emohasis is placed on product quality and ecology of production at this time. New technologies are created still. This technologies are improve quality product and reduce productive cosi to a minimum, while production is the most environmentally. The Semi-solid casting started to developer in the 20 century. Semi-solid casting combines the method of casting and forming. High surface and microstructure guality are guaranteed. However preparation of production is economically costly. The special alloys are suitable for semi-solid casting. Development takes plase still. Aluminium alloys are very utilized for this technology, due to the good mechanical properties.
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Evaluation of corrosion on selected aluminium alloys
Skýba, Pavel ; Tulka, Jaromír (referee) ; Pacal, Bohumil (advisor)
The thesis focuses on the corrosion research of AlCu4Mg1 aluminium alloys of square shape and sheet metal coated in 99.5% aluminium. The theoretical part deals with the characteristics of aluminium, the classification and naming of aluminium alloys and the impact of admixtures on aluminium alloys. In the following chapter a general introduction to metal corrosion, its differentiation according to the type of corrosion attack, mechanisms of corrosion, the impact of corrosive environment, according to the choice of anti-corrosion protection, etc. is given. The main part is devoted to the corrosion of aluminium with a special importance of the impact of admixtures on aluminium alloys, the types of corrosion attack, the impact of corrosive environment as well as of the anti-corrosion protection of aluminium alloys. The corrosion tests in controlled atmosphere are considered in the next chapter, while the last one deals with the evaluation methodology of the process of corrosion. At the beginning of the experimental part all the used samples and materials are introduced. The thesis continues then with an overview and a description of the methods used for experiments. The measurement procedure and the results of the experiments are presented in the following chapter that focuses on the metallographic analysis of the aluminium alloy samples before the experiment and after the corrosion attack. The main part of the chapter deals with the dependence of corrosion speed of the individual aluminium alloy samples on time after being exposed in the climate chamber and the salt fog chamber
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