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Kompozitní materiály a jejich užití v dopravní technice
ZEMAN, Tobiáš
This bachelor thesis is divided into theoretical and practical parts. The theoretical part deals with composite materials themselves, their types, production technologies and especially their use in transport technology. In the practical part, an experimental test of tensile and flexural strength was carried out on carbon fibre samples in order to compare the resulting values. The tensile strength was found to be many times higher than the flexural strength.
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Surface quenching of ductile cast iron
Neduchal, Bronislav ; Roučka, Jaromír (referee) ; Záděra, Antonín (advisor)
This diploma thesis is focused on the surface hardening of cast irons with spheroidal graphite. The work describes a theoretical analysis of the structure and properties of cast irons and individual methods suitable for surface hardening. The practical part describes the production of cast iron castings with spheroidal graphite, on which the surface hardening is performed, tensile test, hardening of produced castings by induction and laser surface hardening, preparation of samples for measuring microhardness and metallographic analysis of metal structures.
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Modifying of a passenger car door hinge
Čermáková, Klára ; Kozman, Zdeněk (referee) ; Píštěk, Václav (advisor)
This thesis introduces issues of passenger car side-door hinges. Practical part of this thesis deals with modifying the current low-cost side-door hinge for Edscha Automotive Kamenice s.r.o. First, material was chosen to decrease weight while maintaining the required mechanical properties. Then follows the detail design of the hinge model, which was created in the software program Catia. Heat and surface treatments are described. Both treatments ensures the hinge's final features. To verify the strength of the hinge, tensile and sag test was simulated in Ansys. Subsequently, record from the consultation of the hinge's manufacturability in series and the hinge’s cutting plans are provided. At the end of the thesis, the assembling procedure is suggested. Final part of the thesis compares the developed low-cost hinge against two similar side door hinges.
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Welding with laser machines
Hanáková, Anna ; Osička, Karel (referee) ; Kalivoda, Milan (advisor)
This bachelor thesis is focused on the usage of laser beam and laser beam machines in engineering. It will be mainly focused on laser beam welding (LBW). History of laser, its development and principal are all described in the opening part of this bachelor theses. Types of lasers and its use are also included. Next part is focused on laser welding itself. Thus, welding methods, parameters entering the process and advantages/disadvantages of this technology are introduced. The last theoretical part includes material tests of welded joint and outputs of those tests. In the experimental part the process of laser welding itself is presented and the results of tensile test are described.
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Mechanical properties of fiber reinforced composites for automotive applications
Bayer, Adam ; Žídek, Jan (referee) ; Jančář, Josef (advisor)
Bachelor’s thesis deals with studying mechanical features of fiber composites. As a matrix was chosen PMMA and as reinforcement was chosen glass fabric. Theoretical part sums up contemporary issues of polymer composites in automotive industry such as their production techniques and methods of impregnation. In experimental part were prepared samples by block polymerization of 30 % solution PMMA in monomer with initiator by 65° Celsius warmth oath, when was fabric directly unfolded in pre-polymer solution. On these samples were executed tensile tests by testing device Zwick and these samples were compared with results of theoreticaly calculated values.
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Parameter Identification for Elastic-plastic Material Models from Experimental Data
Jeník, Ivan ; Šebek, František (referee) ; Kubík, Petr (advisor)
This master's thesis deals with the identification of the material flow curve from record of tensile test of smooth cylindrical specimen. First, necessary theory background is presented. Basic terms of incremental theory of plasticity, tensile test procedure and processing its outputs are described. Furthermore, possibilities of mathematical expression of the elastic-plastic material constitutive law, thus mathematical expression of the material flow curve itself. Mechanism of ductile damage of material is explained briefly as well. Overview of recent methods of the flow curve identification is given, focused on cases, when the stress distribution in a specimen is not uniaxial. That is either kind of analytic correction of basic formulas derived for uniaxial stress state, or application of mathematical optimization techniques combined with numerical simulation of the tensile test. Also unusual method of neural network is mentioned. For 8 given materials, the flow curve identification was performed using different methods. Namely by analytic correction, optimization, sequential identification and neural network. Algorithms of the last two methods were modified. Based on assessment of obtained results, application field and adjusting the parameters of single algorithms was recommended. It showed up, that an effective way to the accurate and credible results is the combination of different methods during flow curve identification procedure.
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Determination of mechanical properties of light metals and alloys and composites via small punch test
Langer, Jiří ; Dobeš, Ferdinand (referee) ; Válka, Libor (advisor)
The aim of diploma thesis is estimate mechanical properties (yield strength, maximum strength and elongation) of light alloys by means of SPT. For the experiments were selected aluminium alloys (Al 2024, Al 6082 T6, Al 7020 and NASA 398) magnesium alloys (MgZnMn, AZ31, AZ61) and composites (AZ91 + 20 % saffilu a Al + Al4C3). Theoretical part of this thesis is focused on analysis of conversion formulas, which were made from SPT data and conventional testing. Experimental part is dedicated to evaluation of experimental data and critical analysis validity of conversion formulas. In this part of thesis is discused the problematics of reproducibility methodology of SPT.
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The use of small punch tests for materials with a higher level of structural inhomogeneity
Gordiak, Michal ; Řehořek, Lukáš (referee) ; Válka, Libor (advisor)
Master's thesis deals with evaluating applicability of correlation relationships between material characteristics determined by Small Punch Test and standard tensile test for material AlSi7Mg0,6 manufactured by casting and technology SLM. Results of Small Punch Tests are correlated with yield strength, tensile strength, elongation, and Young's modulus of elasticity. For each material characteristic various correlation methods are compared, while for each method corresponding coefficients are determined. Consequently, the applicability of individual methods is evaluated by substituting coefficients determined by various studies. Primarily analyzed are correlation methods for which future normalization is expected. The results of master's thesis show that structural inhomogeneity caused by SLM process does not result in high inaccuracies in determining material characteristics. Larger impact on material characteristics has high porosity, which was identified in cast material and led to significant deviations in evaluating tensile strength and elongation.
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