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Structure and Properties of Aluminium Cast Alloys
Samek, Petr ; Podrábský, Tomáš (referee) ; Juliš, Martin (advisor)
The bachelor work is focused on favour of relationship between structure and porperties of aluminium cast alloy AlSi7Mg0,6 in dependence of the effect of cooling rate. The AlSi7Mg0.6 alloy is commonly used in foundry industry to produce high stressed automotive components like motor blocks and cylinder heads. The properties of the material correspond directly to their microstructure which is given by the parameters of the solidification process. Within the frame of experiment were got structural characteristics (DAS, porosity) depending up on method of cooling. There were watched location of structure defects in volume of specimens.
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Low Cycle Fatigue of Magnesium Alloy AZ91
Julišová, Martina ; Podrábský, Tomáš (referee) ; Juliš, Martin (advisor)
The objective of the present study is to investigate the fatigue characteristics of cast magnesium alloy AZ91 after low–cycle fatigue tests at the indoor temperature. Squeeze casting specimens in both non–thermal treatment cast state and in solution annealing state were used as the experimental materials. Cyclic hardening/softening and fatigue life curves were obtained from the tests varying according to the way of thermal treatment. This bachelor thesis includes also fracture tests of specimens. Light microscopy and scanning electron microscopy were used for the investigation.
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Structure and mechanical properties biodegradable Mg-3Zn-2Ca alloy processed by ECAP
Havlíček, Štěpán-Adam ; Podrábský, Tomáš (referee) ; Doležal, Pavel (advisor)
Zaměření této bakalářské práce je na mechanické vlastnosti a mikrostrukturu biodegradabilní hořčíkové slitiny Mg-3Zn-2Ca zpracované pomocí uhlového protlačování skrze shodné kanály (ECAP). Každý vzorek se liší počtem protlaku ve směru Bc. Zpracovaná hořčíková slitina ukazuje zlepšení napěťových a deformačních charakteristik, avšak s rostoucím počtem protlaků začínají klesat deformační charakteristiky. Aplikace ECAP metody způsobila v mikrostruktuře zjemnění zrn a ve směru protlačování prodloužení zrn. Ke studiu mikrostruktury bylo využito světelné mikroskopie a studium tahových vlastností bylo provedeno tahovými zkouškami.
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Design and implementation of Industry 4.0 testbed functional modules
Podrabský, Tomáš ; Pásek, Jan (referee) ; Kaczmarczyk, Václav (advisor)
In this work I deal with the project of an automated robotic bartender, whose task is to show model concepts such as virtual commissioning, digital factory or industry 4.0. The work resolves two parts (cells) for the overall construction. Individual cells are solved from the design and realization of the construction through the virtual verification of operation to the design and realization of the control itself for the given cells. The construction solution was created in SolidEdge ST10. Virtual verification will be solved in the Tecnomatix Process Simulate program and the implementation of PLC and HMI control by Siemens is programmed in the TIA Portal. Wiring diagrams were drawn in the student version of the EPLAN design environment. Other colleagues work on other parts of the barman project.
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Properties and in vitro Degradation of Metalic Biodegradable Materials
Ročňáková, Ivana ; Trojanová, Zuzanka (referee) ; Vojtěch,, Dalibor (referee) ; Podrábský, Tomáš (advisor)
Biodegradable metallic materials for medical applications have received considerable attention in recent years. The main reason is that they provide high potential for fabrication of temporal orthopedic implants such as bone fixation devices. Magnesium is an excellent candidate for fabrication of biodegradable implants due to its biocompatibility, mechanical properties similar to human bone and relevance for biological body functions. The fast degradation rate of magnesium and its biodegradable alloys in physiological environment limits its clinical application. Another attractive material in the field of biodegradable materials is zinc, which is among the essential elements in human body. Zinc exhibits an excellent corrosion resistance, and inferior biocompatibility compared to with magnesium. Hence, surface modification to form a hard, dense/porous, biocompatible and corrosion resistant modified layer has become an interesting topic in magnesium base biomaterials. Since hydroxyapatite is well tolerated by living organisms and in addition, improves the bone growth, it appears to be excellent candidate for such coatings on surface of biodegradable materials (e.g. Mg, Zn). This thesis is focused on comparison of corrosion behavior of pure non ferrous metals (Mg, Zn) and metals coated with hydroxyapatite, in simulated body fluids. The present approach is the use of modified atmospheric plasma spray technology to produce the hydroxyapatite coatings – suspension spraying. Composition and structure of the coatings and corrosion products were studied by light microscopy, scanning electron microscopy equipped with energy dispersive microanalyzer and X-ray diffraction. Corrosion of Mg and Zn samples was monitored by weight loss and determined by X ray and micro-tomography. The application of the HA coating resulted in decrease of corrosion rate of pure Mg. The corrosion rate of coated Mg samples was lower by 27,3 % in comparison with the corrosion rate of pure non coated Mg. Corrosion degradation of uncoated and coated Zn samples was minimal. The aplication of HA on the non ferrous surface appears to be a very promising method to improve corrosion and biological properties of these biodegradable materials.
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Automatic barman
Podrabský, Tomáš ; Horna, Jakub (referee) ; Štohl, Radek (advisor)
I was working on a project of the automated bartender, whose construction has already been done. At the beginning I had to acquaint with construction and understand how it should work. I created the software in developmental environment CoDeSys in version 2.3 and later in version 3.5. Both of them allows the program creation, as well as visualization and online monitoring of PLC operation and debugging. PLC communicates via AS-interface. The aim of this project was to create fully functional application for barman. PLC program is structured as a state machine, which is ideal for this application. State machine is written in the developmental environment in language SFC and its individual steps in LD, ST, or FBD. I focused on simplicity and clarity of the program, in which I tried to incorporate as many features as possible. I managed to create a program that is able to tap one of the 4 or mix of any number of drinks. It can be also said that the operator doesn't want a full glass, but fewer doses than the maximum. The main acquisition for me was the fact that I was able to solve the problem independently, using the programmable controller on a real system, which gave me lots of new skills. The result of this work is fully functional automated barman including visualization that shows the status of sensors, the number of doses for individual drinks and allows to control the whole system and check error messages.
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Influence of Explosive Hardening on the Structure and Characteristic of Hadfield Steel in Terms of use in the Railway Transport
Havlíček, Petr ; Podrábský, Tomáš (referee) ; Nesvadba,, Petr (referee) ; Schmidtová,, Eva (referee) ; Stránský, Karel (advisor)
The high alloyed austenitic manganese steel, the Hadfield steel, thanks to its good wear resistance of the work surface and maintaining the high toughness of the internal material in the same time, is successfully applied for casted crossings. The crossings are the most dynamic stressed components in the railway turnouts. Thanks to low surface and sub-surface hardness the occurrence of plastic deformation and the progressive wear of the crossing running surfaces can be found since the initial stages of the crossing operational life. One possibility how to increase the surface and the sub-surface hardness and this way improve the dimensional stability and the crossing lifetime as well is to apply the explosive hardening of the crossing running surfaces. The technology mentioned above means the application of the explosives in the imminent nearness to the running surface of the crossing, when the high pressure wave acting within the extremely short period actuates the plastic deformation of the material structure. The work deals with analysis of influence of explosive hardening on the structure and characteristic of Hadfield steel. The explosive hardened samples have the surface and the sub-surface hardness checked and the microscopic analysis and X – ray diffraction is applied, including the TEM analysis as well carried out by the transmission electronic microscope. The characteristics experimental testing including outcomes from assessment of the contact – fatigue load of the explosive hardened Hadfield steel samples are the part of the work as well. As an experiment final part the outcomes of the long –term validation, the surface hardness and wear of the crossing running surfaces of the explosive hardened crossing already installed into the Czech Republic railway track are introduced as well.
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Fatigue behaviour of AZ31 and AZ61 magnesium alloys after corrosion degradation
Horynová, Miroslava ; Vojtěch, Dalibor (referee) ; Obrtlík, Karel (referee) ; Podrábský, Tomáš (advisor)
Dissertation thesis is focused on evaluation of influence of exposure in 5% salt fog on fatigue behavior of AZ31 and AZ61 magnesium alloy fabricated by squeeze casting method. Microstructure and mechanical properties of experimental materials have been evaluated. The AZ61 alloy was solution heat treated after prior optimization of the heat treatment process based on microstructural characteristics and mechanical properties. Depths of corrosion damage, corrosion rate and mechanism of corrosion of all three experimental alloys have been evaluated. Influence of prior corrosion exposure for 480 and 1000 hours on fatigue behavior of experimental materials was evaluated. Obtained data were compared with data obtained using smooth test specimens. Fractographic analysis was carried out on both smooth and precorroded specimens. Furthermore, influence of aluminium on corrosion and fatigue behavior of tested alloys was defined.
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Fatigue Behaviour of AZ31 and AZ61 Magnesium Alloys
Gejdoš, Pavel ; Lukáč, Pavel (referee) ; Kohout, Jan (referee) ; Podrábský, Tomáš (advisor)
This doctoral thesis deals with the fatigue behaviour of AZ31 and AZ61 magnesium alloy casted by advanced methods of casting squeeze casting. Based on the regression functions and measured fatigue data were determined fatigue characteristics of these alloys. The work also extends into the area of fatigue cracks in the AZ31 alloy. Were measured fatigue crack propagation rate on modified cylindrical specimens. The paper also outlines the possibilities for describing the fatigue behaviour of AZ61 alloy in extremely low-cycle fatigue.
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Influence of AlCr Layer to Fatiague Properties of Nickel Superalloy IN 713LC at the Temperature 800°C
Šulák, Ivo ; Julišová, Martina (referee) ; Podrábský, Tomáš (advisor)
The present diploma thesis is focused on the effect of AlCr layer on the low cycle fatigue behaviour of cast polycrystalline superalloy IN713LC at 800°C. Protective layer is made by chemical vapour deposition followed by heat treatment. Fatigue tests were conducted in strain control mode with constant total strain amplitude and strain rate. The fatigue behaviour is assessed by cyclic hardening/softening curves, cyclic stress-strain curves, Manson-Coffin curves and Basquin curves. Microstructure was observed in as-received state and also after cyclic loading by means of optical microscopy and SEM.
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