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Assessment of 3D printing technology as an alternative in manufacturing
Balvín, Patrik ; Šafl, Pavel (referee) ; Binar, Tomáš (advisor)
This bachelor thesis is devoted to 3D printing. The main methods od 3D printing, widely used materials (their production, their properties and the advantages and disadvantages of using them), degradation due to enviromental conditions, other common methods of producing polymer parts and mechanical test are described in the theoretical part. This paper also compares the advantages of using 3D printing for prototyping. The experimental section is dedicated to measuring the impact of material degradation on the toughness, hardness, and tensile strength of PLA and PA6 CF15 materials. The case study focuses on the design of an engine spark coil holder and a mobile workstation for 3D printing.
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Small Punch test brittle materials
Saňka, Martin ; Válka, Libor (referee) ; Zapletal, Josef (advisor)
Bachelor’s thesis is focused on description of methods for material testing of miniature samples called „Small Punch Test“. Thesis describes the basic test procedures, interpretation of their results and sample removal techniques. Recognized methods of correlating test results with parameters obtained from conventional material tests and after test sample evaluation were described in the thesis. Furthermore, the thesis deals with the evaluation of mechanical properties of brittle materials using the „Small Punch Test“, where a statistical appoach to obtaining their characteristic strength and specifying the procedure for determining the fracture toughness was described.
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Mechanical properties of large scale 3D printed parts
Strela, Dominik ; Malý, Martin (referee) ; Křivohlavý, Petr (advisor)
This study focuses on the effects of printing parameters on mechanical properties of parts manufactured with FDM (Fused Deposition Modelling) technology. Specimens made from PLA material using the KUKA KR8 R1620 robotic arm underwent tensile test, their shape was designed so to prevent effects of negative phenomena on the results. The results were evaluated and graphically shown. The results show that inter-rastral bonds intensely weaken the parts strength, however a slight material overfill helps strengthen the bonds. The highest tensile strength was measured on specimens with the largest inter-rastral distance and layer hight, with 1,1 as the coefficient of material flow. The results of this study should serve as reference values for future research of properties and behaviours of parts printed using nozzles of larger diameter. They describe the impact of rasterizing products on the final strength.
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Preparation and optimization of a two-layer highperformance cement composite
Kouřilová, Lucie ; Šuleková, Nikola (referee) ; Novotný, Radoslav (advisor)
This bachelor thesis focuses on high-performance cementitious composites with emphasis on the issue of the two-layer concept. The main objective is to design a coarse-grained composite for the front layer with the aim of maximizing the packing density and optimizing the bonding of each layer. High mechanical properties in high performance concrete are achieved, due to the reduction of the water coefficient. In order to optimize the packing density of the coarse-grained cementitious composite, experiments were conducted with different ratios of aggregate types having different particle sizes. The bonding of the layers is influenced by the condition and state of surface, the compaction method and the mechanical properties of the materials. The strength of the bond was evaluated using the tensile strength under three-point bending. The bond strength was affected by the application of a cement paste and in the second case only water on the surface of the face layer.
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Weldability of hardenable aluminum alloys
Filip, Josef ; Slováček, Marek (referee) ; Kubíček, Jaroslav (advisor)
The thesis deals with the influence of MIG pulsed metal transfer welding on the mechanical properties of the aluminium curable alloy and on the presence of defects in the welded joint. The aluminium alloy EN AW 6082 T6 was chosen for the experiment, i.e. in the state after the artificial ageing. The experimental part first describes the selected base and filler material, the used welding equipment, the choice of welding parameters and then the preparation process of the test samples is described. There were made 6 sets of samples, each of them was welded with a different combination of welding parameters and pulsed welding mode. Subsequently, the work deals with several material destructive tests that were part of the experiment. Tensile tests, hardness measurements and microstructure tests were performed. The results of the tensile tests showed that in all cases the tensile strength was decreased by more than 30% compared to the base material and similar values were achieved. Thus, the theoretical assumption that soluble precipitates occur during the welding of hardened Al alloys, causing a decrease in the mechanical properties in the HAZ, was confirmed. It is evident in the results of hardness measurements, which for all samples reached the lowest values in the HAZ at the same place where fractures occurred in the tensile tests. The macroscopic examinations then showed the presence of micropores in all samples except the set num. 4, which did not develop porosity. In several cases, the presence of unbroken or oxide inclusions was also detected. The results are evaluated at the end of the thesis.
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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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Comparison of characteristics of pre-impregnated and conventional carbon fibre epoxy laminates
Jones, Phillip ; Juračka, Jaroslav (referee) ; Katrňák, Tomáš (advisor)
The focus of this thesis is a comparison of pre-impregnated and conventional carbon fibre laminates. The first part focuses on the production process of carbon fibre composites from the process of converting PAN to carbon fibres to the lay-up and curing process of completed parts. The second section includes numerical comparisons of different types of carbon fibre. The data is set up in a fashion to demonstrate the improvements in carbon fibre mechanical properties by comparing outdated carbon fibre to the newest fibre on the market. The included tables aid in the process of choosing the right type of carbon fibre for each specific application.
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