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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 Al-alloy die-castings
Klocová, Petra ; Nová, Iva (referee) ; Čech, Jaroslav (advisor)
The objective of this diploma thesis is an evaluation of die-castings porosity, eventually the evaluation of seats with local squeeze in connection with their mechanical and structural properties. The swatches of alloy AISi9Cu3 were taken from the engine block made by Škoda Auto Company, Mladá Boleslav. To the evaluation and the comparison of the results there were the other VUT FSI Brno students´ theses used.
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Manufacture and defects of heavy castings
Vymazal, Aleš ; Čech, Jan (referee) ; Záděra, Antonín (advisor)
Objective of diploma thesis is to proceed analysis of actual technology in operational terms for concrete casting of bearing . Constructed by foundry of steel ŽĎAS a.s., Žďár nad Sázavou. After designing changes in technological process accomplish detail evaluation of mechanical properties and chemical homogenity of metal at selected parts of sample casting.
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Design of linear motor with permanent magnets
Čech, Jan ; Bulín, Tomáš (referee) ; Knebl, Ladislav (advisor)
The first part of this thesis deals with the study of linear motors. The introduction of the thesis deals with the brief description of the linear motor, including its accessories. This part explains principle of linear motors, their general advantages and disadvantages. The next section contains an overview and division of the currently used linear motors. Each type of currently used linear motors is briefly introduced and also its principle and characteristics are described, including its specific application. The second part of the thesis deals with the design of an equivalent magnetic circuit model of a linear iron-core linear motor. Hereafter, the proposed design will be used to simulate the distribution of magnetic flux in the linear motor. The evaluated flux-density distribution in the air gap is later compared with the results obtained with finite element method. The thrust is then calculated from the flux-density and the estimated value is compared with the value listed in datasheet.
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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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The impact of executing new thermal insulation on a apartment building on the expenses associated with its operation
Machová, Petra ; Kosová, Jaroslava (referee) ; Čech, Josef (advisor)
The topic of the diploma thesis „The impact of executing new thermal insulation on a apartment building on the expenses associated with its operation “ is a draft and appraisal of four variants of thermal insulation of the building. The thesis deals with the assessment of the current proposal for apartment building envelopes along with proposing alternative plans with emphasis on reducing heating costs. The first section describes the types of buildings according to heating demand and a list of different variants of thermal insulation materials. The second part is devoted to a specific apartment building in the Ústí nad Labem for which there are designed in four variants of insulation. The work includes thermal assessment in original condition and the assessment of new condition modified by adding thermal insulation. Through research will bedetermined price of implementation of proposed insulation options together with the costs of operation of the apartment building. In conclusion, the diploma thesis evaluates the payback period of insulation.
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Risk analysis of waterproofing systems of buildings
Vepřek, Karel ; Čech, Josef (referee) ; Novák, Jindřich (advisor)
A general overview of the waterproofing materials. Distribution waterproofing systems according to their use in construction. Listing the possible risks of defects waterproofing systems. Remediation and prevention of defects in the insulation. General summary of the risk lifecycle isolation and analysis of defects in the insulating elements on the real structure.
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The Specifics of Wood-based Constructions Valuation
Hladík, Lukáš ; Čech, Josef (referee) ; Hrdlička, Tomáš (advisor)
The diploma thesis deals with the cost valuation of wood-based constructions, whose amount is growing in the Czech Republic. The aim of this work is to elaborate a detailed itemized budget for three wooden family houses. The price shares were calculated from these budgets; next they were compared with the Regulation 441/2013 Statute book and evaluated. The budgets were also used for a calculation of a unit price, which was compared with a technical-economic index, and commented on as well. On the basis of budgets, the unit price was determined, which was compared with the technical-economic indicator and next comments. The utility properties are compared and evaluated for chosen structures. It is a diffusion-open and diffusion-closed structure. These individual variants of the constructional solution are described and compared with each other. The thesis also presents the basic specifics of wooden-based buildings valuation. In conclusion there is an assessment of adequacy of commonly used price shares of buildings and a proposal for their specification.
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RESEARCH OF HEAVY CASTING METALLURGICAL DEFECTS
Čech, Jan ; Elbel, Tomáš (referee) ; Jelínek, Petr (referee) ; Šenberger, Jaroslav (advisor)
A massive castings defects are examined in this doctoral thesis, specialise in steels passing through peritectic transformation. There are typical types of defects at massive steel castings, as contrasted to „ordinary“ internal and surface ones. For massive steel castings are typical defects under feeders like conchoidal fractures, segregations, microporesities, reoxidation products. Combination of Al and Zr is an ordinary final deoxidation of EOP and LF steel for castings in ŽĎAS a.s. foundry. The aim of Al + Zr combination was to both deep deoxidation by Al (decrease of bubbles risk) and denitrification by Zr (decrease of conchoidal fractures). This theses refute premission mentioned above and verified persisting risk of defects under massive feeders, even though Al + Zr deoxidation is used. A final deoxidation by increased amount of Al was examinated, in combination with other deoxidation agents. Castings had 11 [cm] maximal modulus, and occurence of conchoidal fracture, reoxidation products and primary austenite grain size was evaluated. A selected optimal final deoxidations (Al, Al+Ti, Al+Zr) as a result from experiment described above, were evaluated on castings with 15 [cm] maximal modulus. The result of experiment is, that is not possible to repeatedly produce massive steel casting using EOP metallurgical equipment without defects under feeders, despite of deoxidation and pouring temperature optimalization. The defect indications look like conchoidal fracture, but there are microporesity and impurities instead. Finally, castings with maximal modulus 15 [cm] were produced using so called secondary metallurgy (LF, VD). Secondary metallurgy allowed to both significant decrease of sulfur and degassing of melted metal. Only this metallurgical procedure guarantees production of heavy steel castings without typical defects under massive feeders
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System for precise dynamic measurement of bridge sensors
Čech, Jonáš ; Kolka, Zdeněk (referee) ; Kubíček, Michal (advisor)
This master’s thesis deals with design of measurement system for dynamic measurement of bridge sensors. After a short theoretical part, the own concept is introduced. System can provide sampling rate up to 250 kSa/s with 24-bit resolution. The maximum number of samples is about one and a half milion. At first, the design of analog part was made, in this phase of design the digital part is based on evaluation board with ARM Cortex-M7 and external memory. After final choice of appropriate ICs, the analog and digital part will be integrated into one PCB.
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