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STUDY OF ENERGY ABSORPTION IN MICRO – STRUT LATTICE STRUCTURE PRODUCED BY SELECTIVE LASER MELTING
Vrána, Radek ; Schleifenbaum, Johannes (referee) ; Skalon, Mateusz (referee) ; Paloušek, David (advisor)
Předložená dizertační práce je součástí většího výzkumného projektu, který si klade za cíl využití mikro prutové konstrukce vyrobené technologií SLM jako absorbér rázové energie s přesně navrženými vlastnostmi. Hlavním cílem práce je vývoj numerického modelu deformačního chování mikro-prutové konstrukce vyrobeného technologií Selective Laser Melting (SLM) z materiálu AlSi10Mg. Aby bylo možné dosáhnout hlavního cíle dizertační práce, bylo nutné analyzovat vliv procesních parametrů technologie SLM na tvorbu vnitřních materiálových vad a drsnost povrchu při výrobě mikro-prutové konstrukce. Tyto imperfekce degradují její mechanické vlastnosti a jejich odstranění zlepší možnosti a přesnost numerické predikce. Výsledky ukazují významný vliv dvou hlavních parametrů – skenovací rychlosti laseru a výkonu laseru. Na základě těchto poznatků byly dále definovány parametry vstupní energie Ein a lineární energie Elin, které zahrnují oba zmíněné parametry a byly definovány jejich limitní hodnoty pro minimalizaci vzniklých imperfekcí. Deformační chování vyrobené mikro-prutové konstrukce bylo analyzováno na navrženém pádové zařízení, které umožňuje testování s dopadovou energií až 120 J. Deformační chování je vyhodnocováno s využitím obrazové analýzy záznamu vysoko rychlostní kamery a silového průběhu z tenzometru. Výsledky analýzy byly využity pro validaci numerického modelu v programu ANSYS Explicit, do kterého byly implementovány poznatky o reálném tvaru vyrobeného mikro-prutového materiálu ve formě eliptického modelu geometrie a informace o reálných mechanických vlastnostech ve formě vyvinutého materiálového modelu. Výsledné porovnání výsledků experimentu s predikcí numerického modelu ukazují dobrou shodu v místě maximálního zatížení Fmax (odchylka 5 %) i průběhu celé deformace vzorku. Tyto poznatky budou v budoucnu využity při návrhu absorbéru energie s definovanými mechanickými vlastnostmi.
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Numerical model of lattice structure under dynamic loading made by Selective Laser Melting technology
Červinek, Ondřej ; Maňas, Pavel (referee) ; Vrána, Radek (advisor)
For the purpose of mechanical impact energy absorption in the transport industry are mainly used special profile absorbers. For highly specialized applications is required to use components that are designed for specific kind of deformation. Example of these parts are industrial-made metal foams or micro-lattice structures produced by SLM technology. This paper focuses on low-velocity dynamic loading prediction of BCC micro-lattice structure made of aluminum alloy AlSi10Mg by SLM technology (SLM 280HL). For this purpose dynamic FEM simulaton of the micro-lattice structure was developed, supplemented by model of BCC structure material obtained from mechanical testing. Real geometry of tested samples obtained from optical measurement (Atos Triple Scan III) was further implemented in the numerical model. Dynamic BCC structure load experiment was performed on a drop-weight tester. Behavior of structured material in drop-weight test was described by the course of deformation and reaction forces over time. Comparable results were obtained for flat loading of dynamic FEM simulation and experiment. Inclusion of production phenomena in simulation led to increased accuracy and compliance with experiment. Tool for testing the effect of geometry change on mechanical properties was created. To achieve more accurate results with puncture load, it is necessary to modify the material model with real material deformation at test sample failure.
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Design of injection molding cooling insert for manufacturing by Selective Laser Melting
Tekeľ, Richard Martin ; Vrána, Radek (referee) ; Koutný, Daniel (advisor)
This bachelor thesis focus on design of a cooling insert so the current mold cycle time will be reduced and it will be possible to manufacture the insert by SLM. Proposed modification includes 1 cooling line with non-circular cross section and disrupt empiric cooling line design recommendations. A research into differences of conventional and additive manufacturing of injection moulding inserts was conducted as well as into theoretical principles needed for a design of cooling lines and preview of similar solutions for the given task. After simulation of current state and obtaining a value of current cycle time, 3 different designs of cooling line were chosen and simulated in order to pick the most suitable one. This cooling design was afterwards modified to get conformal shape and lower distance from critical spot. The last part of thesis interpret the results from simulation of the final cooling line design and estimation of safety against fatigue failure.
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Development of 3D metal printing process parameters for producing of the lattice structure
Jaroš, Jan ; Koutný, Daniel (referee) ; Vrána, Radek (advisor)
Selective laser melting (SLM) in additive technology, which allows production of lattice structures. Lattice structures are very difficult to produce using conventional methods. The main use of lattice structures is in aerospace industry and medicine for bone implants production. In this work influence of processing parameters (laser power, scanning speed) on properties (diameter, surface roughness, porosity) of struts is investigated. The processing parameters selection was based on single tracks test. In the first test, ImageJ was used to determine porosity of struts. In the second test porosity was analyzed with more accurate µCT technology. Both tests used 3D scanning technology to determine dimension accuracy and surface roughness of samples. The measurement results led to the detection of processing parameter „window“ where samles had the best combination of surface roughness and porosity. The best results were achieved with 225-275 W laser power and scanning speed of 1400-2000 mm·s-1.
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Parametric model of injection mold
Tomanec, Pavel ; Vrána, Radek (referee) ; Brandejs, Jan (advisor)
This bachelor thesis is concerned with creating parametric model of plates injection mold for plastic by using software CatiaV5. It is used for faster and more efficient in the design of the injection mold. The first section describes the basic design and technological elements for designing injection molds. The second part describes the system for creating and constrain the parameters finally verify the functionality of the created model.
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Evaluation of Mechanical Properties of Lattice Structures Made by 3D Metal Printing
Pliska, Jan ; Skřivánková, Vendula (referee) ; Vrána, Radek (advisor)
Additive manufacturing technologies allow manufacturing of complex structures which are near impossible to manufacture by other more conventional technologies. A fine example of these complex structures is a periodic metallic micro-cellular structure This bachelor thesis is focused on summarization of known mechanical behaviour of lattice structures manufactured via Selective Laser Melting. This study also investigates suitable comparison criteria for lattice structures. Required values for determination of material constants were obtained from mechanical testing of real specimens. For faster evaluation of mechanical testing, automatic script in MS Excel was created. Research showed up some of the major parameters characterising the mechanical behaviours of lattice structures. It is possible to compare qualities of lattice structures based on criteria presented in this work.
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Process Parameters Development for Producing of Lattice Structures Using 3D Metal Printing
Moravčik, Jaroslav ; Koutný, Daniel (referee) ; Vrána, Radek (advisor)
Selective laser melting (SLM) belongs to additive technologies. Progressive adding of layers of material powder and creating the structure with laser beam allows to create components with complex shapes, for example microstructures. This thesis explores potential of new printing strategies, which could lead to good melting of printed component and reaching to better structure without porosities. Based on analysis of actual state, software for calculation of laser trajectory was made with use of new printing strategy. Also, process parameters obtained from technical articles and from experiments made on Institute of Machine and Industrial Design on Faculty of Mechanical Engineering BUT in Brno were compared. This comparison led to suggestion of test set of components with new parameters and strategies. This set could lead to new researches in this issue.
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Alternative design of the Dětkovice sewer network
Vrána, Radek ; Beránek, Josef (referee) ; Ručka, Jan (advisor)
The aim of this diploma thesis is to elaborate alternative designs of the Dětkovice sewer network. The first part deals with reasons of this work and the area of interest. In the next part the thesis deals with describe of current condition and proposed alternative designs. Furthermore, the economic assessment of alternative designs is elaborate.
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