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Assessment of the use of 3D printing technology in the automotive industry
Ondriska, Josef ; Libich, Jiří (referee) ; Binar, Tomáš (advisor)
This thesis deals with 3D printing technology and analysis of various polymeric additive manufacturing materials, with a focus on their application in the automotive industry. In the experimental part, three types of material are tested for mechanical properties, both without degradation and after degradation by a climate chamber. In the tensile strength test, the possibility of using acoustic emission as a diagnostic method was verified. From the results obtained, a specific part used in the automotive industry was designed. The work also includes the design of a stationary
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Characterization of surface and mechanical properties of microbial cells
Khýrová, Markéta ; Lukeš,, Jaroslav (referee) ; Plichta, Tomáš (advisor)
The subject of this diploma thesis is the characterization of bacterial strains capable of polyhydroxyalkanoates (PHA) production in terms of morphology and mechanical properties. With this aim, an atomic force microscope (AFM) was used together with a nanoindentation instrument to perform microcompression tests on selected microorganisms. The model bacterial strains, Cupriavidus necator and Rhodospirillum rubrum, were tested in their PHA-producing form and in their mutant non-producing variant, in order to study the effect of PHA amount on bacterial morphology and mechanical properties. In the experimental part of this work, the preparation of native bacterial samples for both techniques were first optimised. Glass substrates were treated with plasma and the cells were subsequently fixed with poly-L-lysine. In addition, sample preparation including fluorescent staining was optimized for the microcompression tests in order to easily detect cells and determine their size. Finally, the impact of different measurement parameters and mathematical models for calculating Young's modulus on the AFM data were evaluated. The results revealed the effect of PHA on bacterial cell morphology and showed that PHA producers exhibit higher Young´s modulus on average compared to their mutant. It was also shown experimentally that microcompression tests provide significantly higher Young's modulus values than those obtained by AFM.
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Controlled modification of tips usable for selected measurement modes of atomic force microscopy
Lišková, Kateřina ; Szabová, Jana (referee) ; Smilek, Jiří (advisor)
This master's thesis deals with the modification of tips commonly used in atomic force microscopy and their following utilization for determining the mechanical properties of selected hydrogel systems at the local level. For targeted modification, a method of micro-particle fixation on a cantilever was chosen, which was successfully modified using melamine resin particles. Initially, the mechanical properties of a selected representative of physically cross-linked hydrogels (agarose polysaccharide) were measured, which were evaluated based on the Young's modulus of elasticity, adhesive force, and work. The obtained results were compared with values measured using two commercially available cantilevers differing in both shape and basic parameters such as spring constant and resonance frequency. Subsequently, the influence of the setpoint force applied to the sample by the cantilever was verified. The usability of modified cantilevers was also tested on a selected representative of ionically cross-linked hydrogels (sodium alginate cross-linked with multivalent ions). Within the experimental part of the master's thesis, it was verified that the use of cantilevers with a higher contact area leads to more reliable results in terms of reliability and reproducibility, considering that the final value of the Young's modulus includes not only the contribution of the polymer chain but also the pores. When determining mechanical values, it is important to specify not only the cantilever used and its properties but also all other experimental parameters, the change of which may affect the final values of the Young's modulus determined at the micro level by atomic force microscopy.
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Evaluation of washing effect on material properties after 3D DLP printing
Uvíra, Dominik ; Jaroš, Aleš (referee) ; Zemčík, Oskar (advisor)
This thesis focuses on the influence of washing on the mechanical properties of 3D DLP printed parts. The aim of the thesis was to experimentally determine the impact of washing agents with different wash durations on the mechanical properties of 3D printed parts using DLP technology. The research describes the devices and materials used. Furthermore, an analysis of washing 3D DLP printed parts is conducted, including a description of polymer dissolution, types of washing agents, and washing methods. Based on the research, materials were selected, including Standard resin, ABS-like resin, and Tough resin. The used washing agents are IPA, Simple Green industrial degreaser, DPM, and a special uncured resin remover called EasyClean. Samples were produced on the DLP 3D printer Anycubic Photon D2, and printing profiles were established based on the research part and own calibration. In the first experiment, the effectiveness of the agents in removing uncured resin was monitored. This was followed by an experimental evaluation of the tensile properties of the prepared samples. Furthermore, the notch toughness of each material was evaluated. In both cases, an analysis of fracture surfaces was conducted. Based on the achieved results, optimal washing durations were determined for all material and rinsing agent combinations, and areas of application were recommended. Subsequently, a custom rinsing agent combining low cost and good mechanical properties was proposed. The final part of the work consists of an economic evaluation of the various rinsing agents, resulting in specific recommendations for purchasing rinsing agents and rinsing duration.
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Hydrogels modified by amphiphilic structures
Heger, Richard ; Sedlařík, Vladimír (referee) ; Kráčalík, Milan (referee) ; Pekař, Miloslav (advisor)
The submitted dissertation deals with the influence of amphiphilic structures on hydrogel properties. Additions of various amphiphilic substances associated with the formation of highly ordered structures affect the mechanical, transport and structural properties of hydrogels. The main inspiration for this type of work was living tissue, more precisely the extracellular matrix, which is often mimicked by hydrocolloids, and its high orderliness is responsible for its unique properties. The knowledge obtained from this tissue was applied to the hydrogel systems studied in this work. Various cross-linked hydrogel matrices (physically cross-linked agarose and gelatin, ionically cross-linked alginate and chemically cross-linked mixture of polyvinyl alcohol and chitosan) were suitable representatives for this work. These hydrogel systems were modified by the addition of various amphiphilic substances. The human body’s own phospholipid, lecithin, or variously charged more classic surfactants (CTAB, SDS and Triton X-100). Experimentally, this work is divided into three areas, the study of mechanical properties using rheology, the description of transport properties via release and flow experiments using various model drugs (rhodamine 6G, eosin B, amido black 10B, methylene blue and riboflavin), and morphological characterization using SEM. The characterization of hydrogel systems was supported by other techniques used in this work, such as drying and swelling experiments or gas sorption.
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Advanced high-temperature resistant metal-ceramic composites based on TiB2 for cutting tools
Halmazňa, Jiří ; Drdlík, Daniel (referee) ; Chlup, Zdeněk (advisor)
This diploma thesis deals with the preparation of new high-temperature resistant cermets based on TiB2. The hard ceramic phase is bonded by NiW metallic alloy, which was prepared by mechanical alloying using a planetary ball mill. The first part of the thesis is targeted to the optimization of mixing of both powders in the planetary ball mill. The procedure of preparation of powders mixture with homogenous particles distribution of the NiW alloy was designed and verified with simultaneous particle size refinement. The second part is focused on the microstructure characterisation and mechanical properties evaluation of sintered materials. In this case both powders, TiB2 and NiW, were mixed in a tubular mill and consequently compacted by a rapid hot pressing method at four different sintering temperatures. The influence of the sintering temperature on the microstructure development characterized by the density, porosity and grain size was monitored. The elastic modulus, fracture toughness, flexural strength and hardness were measured on prepared test specimens. The results of conducted experiments show a significant dependence of the microstructure and mechanical properties on applied sintering temperatures. The higher sintering temperatures are used the better mechanical properties are observed. However, the sintering temperature of 1375°C seems to be an optimal one. The sintering temperature of 1400°C leads to the significant losses of the metal phase due to sublimation of nickel resulting in increased porosity in the metal phase regions.
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Utilisation of already deposited energy by-products in cement production
Lukášek, David ; Švec, Jiří (referee) ; Opravil, Tomáš (advisor)
This bachelor thesis focuses at study of deposited high-temperatured fly ash and its utilization in production of cement. The theoretical part of the bachelor thesis deals with the production and division of cements. The individual advantages and disadvantages of high-temperature and fluid fly ash when added to cements are addressed. The theoretical knowledge was used to design subsequent experiments. The conclusion of the theoretical part of the work deals with pozzolans. The main content of the experimental part was the analysis of raw materials and subsequent analysis of the mechanical properties of the prepared mixtures. The experiments were designed in accordance with valid standards.
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Fatigue properties of materials prepared by SLM method
Hanáček, Josef ; Pantělejev, Libor (referee) ; Štěpánek, Roman (advisor)
This work deals with description of SLM (Selective Laser Melting) method, which is one of ALM (Additive Layer Manufacturing) method. In first part the general laws of fatigue and SLM method are described. The second part deals with the influence of processing parameters to final properties of material. The main goal of work is to determine dependence between processing parameters and mechanical properties of SLM processed components. Special attention is dedicated to fatigue properties.
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Development of process parameters for Selective Laser Melting technology for processing of aluminum alloy AlSi7
Zvoníček, Josef ; Dočekalová, Kateřina (referee) ; Koutný, Daniel (advisor)
The diploma thesis deals with the study of the influence of process parameters of AlSi7Mg0.6 aluminum alloy processing using the additive technology Selective Laser Melting. The main objective is to clarify the influence of the individual process parameters on the resulting porosity of the material and its mechanical properties. The thesis deals with the current state of aluminum alloy processing in this way. The actual material research of the work is carried out in successive experiments from the welding test to the volume test with subsequent verification of the mechanical properties of the material. Material evaluation in the whole work is material porosity, stability of individual welds, hardness of the material and its mechanical properties. The results are compared with the literature.
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