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Structural and Mechanical Characteristics of Nickel-Alloyed Ductile Cast Iron
Tesařová, Hana ; Kohout, Jan (referee) ; Kruml, Tomáš (referee) ; Konečná,, Radka (referee) ; Pacal, Bohumil (advisor)
The aim of this dissertation work is the evaluation of the influence of nickel alloying on the structure and mechanical properties, both monotonic and dynamic, of nodular cast iron with ferritic and bainitic matrix. Two chock melts with 0.5 and 2.7 % Ni were used to study the nickel influence. The quantitative evaluation of structure of these melts using image analysis was done and basic tensile mechanical properties were determined. Subsequently, the time optimization of two-stage ferritic annealing and isothermal austempered heat treatment at 375 °C was performed with the aim to obtain optimal ferritic and bainitic structures with best static and dynamic mechanical properties. After ferritic annealing the nickel alloying contributes to substitution hardening of ferritic matrix which positively affects its strength and other mechanical properties. The higher nickel content in the bainitic structure causes the shift of phase transformation times to longer times which results in restricted production of small carbides and in bigger volume of retained austenite. These features were confirmed by observation in transmission electron microscope. Precise tensile and low cycle fatigue tests at temperatures 23 and – 45 °C were performed on the optimized structures of both nodular cast irons. As a result of the notch effect of graphite nodules, microplastic deformation of both nodular cast irons was observed at stresses which were lower than the yield stress. The Hollomon's equation very well describes the individual parts of tensile curves for both nodular cast irons including their mutual comparison. From the low cycle fatigue tests, the cyclic hardening/softening curves, the evolution of elastic modulus and hysteresis loop shape parameters, cyclic stress-strain curves and fatigue life curves were obtained for both temperatures and materials. Moreover, the decrease of retained austenite volume was measured by neutron diffraction and the evolution of surface relief was characterized during cyclic straining for both austempered nodular cast irons at both temperatures. On the basis of these results both cyclic plasticity and fatigue degradation mechanisms in relation to the cyclic strain localization were described for both nodular cast irons.
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Determination of the mechanical properties of materials used for 3D printing
Černý, Martin ; Sliwková, Petra (referee) ; Sedlák, Josef (advisor)
The thesis deals with the determination of mechanical properties of materials used for 3D printing (ABS, nylon and PLA). Standardized samples produced using a 3D printer using the Fused Deposition Modeling method were subsequently used for mechanical testing. The work is also extended to determine the mechanical properties of samples made by Soft Tooling. For the production of Soft Tooling samples, polyurethane resins SG 2000 and SG 145 were used. Individual materials were analyzed by mechanical tests (tensile test and hardness test). Surface integrity parameters have also been determined for 3D-printed materials. Parameters were selected from the individual tests (tensile strength, modulus of elasticity) ductility and hardness), which were subsequently statistically processed. The work is concluded by evaluating the results obtained, which were compared with the values given in material sheets.
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Optimalization of parts bonded by hot crimping
Liškář, Ladislav ; Řiháček, Jan (referee) ; Lidmila, Zdeněk (advisor)
The thesis describes the procedure for verifying the conceptual ideas of the company. Design and production of prototypes, testing and evaluation, quantifying savings. Two variants of crimped bond were chosen. For each was length of shaft changed to three and four crimped grooves. These prototypes were tested in two static and one dynamic tests. Recommendation for company is continue with other phases of development for shaft with four grooves.
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Assessment of heterogeneous properties butt welds in laser welding and electron beam welding
Rozsypal, Oldřich ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
The project was developed within the engineering degree in engineering technology, and is focused in welding together of two different materials. Welds will be done on a high strength steel Domex 420 MC and deep drawing steel DC01 using laser welding, and will be compared with the method of electron beam welding. Part of this project is a scientific research describing the basic physical principles of both methods, different types of lasers, welding material properties and inspection of welds. In the experimental part was carried tensile test, macroscopic and microscopic examination. Finally, work is to evaluate the individual tests.
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Mechanical Properties of Plastics
Suchý, Marek ; Němec, Karel (referee) ; Molliková, Eva (advisor)
This bachelor thesis deals with the plastics in terms of their internal structures. Analyzes the impact of these characteristics on the resulting mechanical properties of materials. Furthermore, examining the external influences significantly on the polymer chain operates. Concludes two basic methods for the detection of mechanical properties - tensile test and 3-point bend tests.
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Mechanical properties of polymers produced by 3D printing technology
Král, Filip ; Moravčík, Igor (referee) ; Válka, Libor (advisor)
The thesis deals with the dependence of mechanical characteristics on the anisotropy of polymers Nylon 12 and Ultem 9085 made by a 3D printing technology Fused Deposition Modeling (FDM). The evaluation of the material characteristics was performed on the basis of tensile and non-instrumental impact tests. It was proven that the material characteristics are strongly dependent on anisotropy, i.e. on layer thickness and raster angle for both types of polymers.
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Analysis of mechanical properties of plastic samples produced by 3D printing technology
Jiroušek, Jan ; Joska, Zdeněk (referee) ; Sedlák, Josef (advisor)
The master's thesis deals with the determination of mechanical properties of materials used for 3D printing (PLA, PETG, ABS, ASA). The theoretical part contains characteristics of polymer materials and describes testing of mechanical properties and additive technologies. In the experimental part, the standardized samples produced by the technology Fused Filament Fabrication were analysed using mechanical tests (tensile test and hardness test). Some of the examples were exposed to the selected factors of degradation. Selected parameters from mechanical testing (tensile strength, modulus of elasticity in tension, elongation and Shore hardness) were statistically processed. The conclusion of the thesis evaluates the impact of the factors of degradation on particular materials and compares them subsequently.
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Production of sunglases parts using a 3D FDM printer
Řepa, Dominik ; Sliwková, Petra (referee) ; Zemčík, Oskar (advisor)
The diploma thesis deals with the design of specific sunglasses produced by the FDM 3D printing method. The theoretical part contains characteristics of sunglasses and their production, characteristics of individual 3D printing methods, materials, 3D printer components and parameters for 3D printing of the model. In the experimental part, the 3D printed samples, which were heat treated to different temperatures, were subjected to a mechanical tensile test. In the next experimental part, regular sunglasses were subjected to hinge strength measurements. The evaluated parameters were evaluated and applied to the model. The resulting model was verified using FEM and a physical prototype of the sunglasses was subsequently created.
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