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Additive manufacturing of spatial trusses from polymeric materials
Křivohlavý, Petr ; Němeček, Stanislav (referee) ; Škaroupka, David (advisor)
This thesis is focused on creating polymer lattice struts without any necessary support in full length using robotic 3D printing. The aim of the thesis is to find suitable process parameters and printing strategies with respect to the accuracy of the polymer struts. A statistical model of effects of individual process parameters has been produced to achieve stated objectives. The model enables finding optimal process parameters. The printing strategies for thus established process parameters are tested to increase the accuracy of the finished print and the quality of the bonds between individual struts. The accuracy assessment is executed using optical 3D metrology. The maximum deviation from the nominal shape 0.54mm has been accomplished using discovered process parameters and printing strategies.
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System of large-scale 3D printing of products from bar structures
Vašátko, Marek ; Němeček, Stanislav (referee) ; Škaroupka, David (advisor)
This thesis deals with the design of a system for the production of lattice spatial structures from polymer materials printed by a robotic arm. The aim of the thesis is to design a suitable manufacturing system in general and to experimentally verify the production of products on the current form of the system. Using compression tests to determine the load carrying capacity of the fabricated lattice structures and compare it with a computational model of the ideal geometry. In general, the parts of the manufacturing system were designed and experimental measurements of compression tests on fabricated specimen structures were carried out. The first results of compression tests of such fabricated structures for two cell topologies were obtained. The accuracy between the experiments and the computational model is comparable to the results in the current literature. Better results were obtained in the areas of repeatability of the obtained load values. The system is a combination of HW and SW solutions providing 3D printing of large-scale lattice structures for large volume parts and represents an incremental improvement of partial properties.
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Topology optimisation using lattice structures
Černák, Martin ; Maňas, Pavel (referee) ; Vaverka, Ondřej (advisor)
This thesis aimed to develop and verify the methodology for lattice topology optimization, which deals with additive manufacturing specifications and is independent of the optimization solver. The developed methodology uses the SIMP topology optimization algorithm. The penalization factor used for a solution is based on the mechanical properties characterizing arbitrarily chosen unit cell. These are identified using the homogenization method applied to the real geometry specified by 3D optical digitization. Verification is based on FEA using the variable homogenized properties. The local stress response is simulated by submodeling technique. The methodology was verified by optimizing the braking shield bracket of a plane. The optimized part is 22 % lighter and 31 % stiffer than the original solution. Results of the thesis demonstrate that the proposed methodology is suitable for structural part optimization and allows us to use lattice structures together with topology optimization and additive manufacturing relatively easily, not only in the space industry.
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Research on process parameters for producing of a structured material made by Selective Laser Melting technology
Richter, Vladislav ; Koutný, Daniel (referee) ; Vrána, Radek (advisor)
Selective laser melting (SLM) is one of additive technologies which allows manufacturing of components with very complex shape. One of the examples are porous lattice structures which are used in cosmonautics or medicine due to its good mechanical properties and low weight. In this work the influence of processing conditions (laser power and laser scanning speed) on material properties and geometry of as-fabricated trusses is investigated. Wide range of laser powers (100–400 W) and laser scanning speeds (1000–10000 mm/s) were used to determine optimum process parameters. Truss size, morphology and internal porosity was investigated using optical 3D scanner and X-ray micro computer tomography (mCT). Based on executed measurements optimum processing conditions were determined to be 350 W and 3000 mm/s. It is possible to manufacture faster geometrically more precise structures with equal internal porosity due to optimization.
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Experimental investigation of mechanical properties of structures made by metal 3D print
Porubský, Radek ; Jaroš, Jan (referee) ; Vaverka, Ondřej (advisor)
This bachelor thesis deals with shear testing of lattice structures produced by the Selective laser melting technology. The testing method was based on the ASTM D7078 standard, which deals with the testing of composites. BCC and FCC lattice structures with different strut diameters were selected for the experiment. The work describes the course and results of shear test. These real results are compared with results of finite element analysis. The results compare the properties of structures depending on the diameter of the strut, the type of structure or the direction of loading. The influence of Selective laser melting production technology on the properties of structures under shear loading is also discussed. For example, the results showed that the FCC structure has better mechanical properties under shear loading than the BCC structure. For both structures, it was also confirmed that structures with a larger strut diameter have significantly better properties than those with a smaller strut diameter.
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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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Analysis of thermal behavior focused on additive manufacturing of lattice structures from AlSi10Mg
Nosek, Jakub ; Dočekalová, Kateřina (referee) ; Paloušek, David (advisor)
Using Additive manufacturing it is possible to manufacture complicated components, that cannot be manufactured using conventional methods. The typical example is the lattice structure. Fabrication of these structures is complicated, and it is different from the fabrication of bulk parts. Using numerical simulation which can reflect process parameters it is possible to analyze the thermal behaviour of vertical and inclined struts fabrication. Results show that the diameter of struts influences weld track width. This influence is caused by preheating the powder material by previous scanning paths. The final geometry of inclined struts is made in more scanning layers. In this work influence of the start and endpoint of trajectory is described.
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Impact loading of lattice structures produced by Selective Laser Melting technology from magnesium alloy WE43
Foltán, Tomáš ; Červinek, Ondřej (referee) ; Jaroš, Jan (advisor)
Strut-based lattice structures manufactured with magnesium alloy WE43, due to their high strength-to-weight ratio, seem like an ideal solution for biomedical and aerospace industries. Previous research has focused mainly on the behaviour of these structures under quasi-static stress conditions. Dynamic stressing of these structures has not been deeply researched. Therefore, this work deals with impact testing of strut-based lattice structures manufactured by SLM. Low-velocity impact tests were performed on a set of cell topologies with different strut diameters. Absorbed energy, stress-strain curve, and deformation mechanism of each sample were studied. Clear effect of cell topology on the amount of absorbed energy was observed, where structures of similar relative densities displayed considerably different values. Highest specific absorbed energy was achieved with the FCCZ cell. In comparison with other materials (e.g., steel) magnesium proved to be far less efficient. This was most probably caused by its brittle fracture failure mode. Conducted tests give insight into mechanical behaviour of magnesium alloy structures under dynamic compression and their ability to absorb energy. Collected data may prove useful for biomedical applications e.g., in designing bone implants.
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Computational Models for Non-linear Mechanical Loading Analyses of Lattice Structures Made by Laser Powder Bed Fusion
Červinek, Ondřej ; Dr. Michael R. Tucker (referee) ; Haas/, Franz (referee) ; Koutný, Daniel (advisor)
Rozvoj aditivních technologií v posledních letech umožnil výrobu meta materiálů s porézní vnitřní architekturou zvaných mikro-prutové struktury z několika typů kovových slitin. Za pomoci těchto struktur je možné vyvíjet lehké komponenty s potenciálem v oblasti absorpce mechanické energie. Jejich implementací do deformačních zón vozidel může být docíleno zvýšení bezpečnosti posádky. Vlastnosti mikro-prutových struktur umožňují navrhnout absorbéry se specifickým typem chování, které redukuje přetížení působící na posádku vozidla v případě nehody. Pro využití těchto dílů pro specifické aplikace je nutné odhadnout jejich deformační chování. Nedávný výzkum ukázal, že základový materiál těchto struktur má odlišné vlastnosti v porovnání s konvenčními objemovými komponentami vyrobenými stejnou technologií. To znamená, že pro efektivní využití mikro-prutových struktur je zapotřebí matematicky přesně popsat jejich specifické vlastnosti a deformační charakteristiky. Nicméně matematický model, který by zahrnoval popis všech významných charakteristik deformace mikro-prutových struktur, není k dispozici. Proto se tato práce zaměřuje na vývoj nelineárního numerického modelu zatěžování mikro-prutových struktur se zahrnutím efektů spojených s nejvýznamnějšími geometrickými imperfekcemi, specifickými vlastnostmi multi-prutových vzorků a dynamickými efekty. Struktury jsou vyrobeny z hliníkové slitiny AlSi10Mg a nerezové oceli 316L s využitím technologie selektivního laserového tavení. Dva odlišné přístupy jsou použity k vytvoření modelu geometrie, což umožňuje detailní inspekci deformačního charakteru. Výsledky obou modelů potvrzují, že geometrické imperfekce spojené se změnou tvaru a velikosti průřezu prutu mají významný vliv na výsledné mechanické vlastnosti. Jejich zahrnutí do modelu geometrie zvyšuje přesnost výsledků simulace. Navíc mechanické vlastnosti mikro-prutových struktur stanovené pomocí multi-prutových vzorků výrazně lépe representují vlastnosti struktur pro kvazistatické i dynamické zatěžování. Finální parametrická ověřovací simulace zatěžování mikro-prutové struktury při několika rychlostech ukazuje dobrou shodu experimentu a výpočtového řešení. Podobná parametrická studie může v budoucnu vést k nalezení efektivních strukturovaných konfigurací pro specifické množství absorbované energie bez předchozí výroby a testování.
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