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Effect of layer thickness on critical angle of additively manufactured lattice structures
Nosek, Jakub ; Vrána, Radek (referee) ; Vaverka, Ondřej (advisor)
Aim of this work is to describe the effect of a layer thickness on critical angel of a lattice structures manufactured by SLM technology. The effect of layer thickness was investigated on single struts and on lattice structures made from stainless steel 316L. Better geometrical accuracy could be obtained, if the smaller layer thickness is used. Less attached powder particles on downskins was also observed on lattice structures. Thanks to this thesis, it is possible to determine, if it is meaningful to decrease the layer thickness in order to improve manufacturability of lattice structures even with higher manufacturing time.
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Comparison of micro-lattice structures for energy absorption
Koban, Tomáš ; Vrána, Radek (referee) ; Červinek, Ondřej (advisor)
Additively manufactured metal micro-structures have great potential in energy absorption applications. The recent research in this field led to a much better understanding of failure behaviour of these micro-structures. This thesis focuses on comparison of energy absorption ability of strut-based micro-lattice structures manufactured by selective laser melting depending on their topology and basic material. Energy absorption of three types of lattice structures (BCC, BCCZ, GBCC) made from stainless steel 316L and aluminium alloy AlSi10Mg was examined. Specific energy absorption was used to compare the two materials. The results show that micro-lattice structures made from stainless steel outperform the aluminium ones in energy absorption ability. The highest amount of absorbed energy was measured for BCCZ structure. This thesis describes the failure mechanism of micro-lattice structures and offers a complex evaluation of energy absorption for both materials.
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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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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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Micro-lattice structures with variable strut diameter
Brulík, Karel ; Jaroš, Jan (referee) ; Červinek, Ondřej (advisor)
Due to their specific properties, micro-lattice structures have a great potential for use in energy absorption applications. It turns out that conventional micro-lattice structures with constant volume fraction can be designed for a known amount of absorbed energy. In real applications, however, we often do not know it in advance. Therefore, the use of functionally graded micro-lattice structures, which can be designed for a wider range of applied energies, appears to be more promising. The aim of this work is to compare micro-lattice structures with variable strut diameter made from 316L stainless steel by Selective Laser Melting technology in terms of energy absorption capability. For this purpose, two types of structures, F2BCC and F2BCC_45, were fabricated, both in configuration with constant, continuously variable and stepwise variable strut diameter. The structures were subsequently dynamically loaded using a drop-weight test, the results of which were described by the time history of deformation and forces. The greater amount of absorbed energy was measured for structures of type F2BCC_45, up to 73 % depending on the configuration of the structures. The results revealed that the variable strut diameter does not have a large effect on the amount of absorbed energy, but it significantly reduces the shock generated, up to 54 % depending on the type and configuration of the structure. This thesis provides a comprehensive view of the deformation and stress characteristics of both types of structures, and in particular a comparison of the effect of variable strut diameter.
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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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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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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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Comparison of micro-lattice structures for energy absorption
Koban, Tomáš ; Vrána, Radek (referee) ; Červinek, Ondřej (advisor)
Additively manufactured metal micro-structures have great potential in energy absorption applications. The recent research in this field led to a much better understanding of failure behaviour of these micro-structures. This thesis focuses on comparison of energy absorption ability of strut-based micro-lattice structures manufactured by selective laser melting depending on their topology and basic material. Energy absorption of three types of lattice structures (BCC, BCCZ, GBCC) made from stainless steel 316L and aluminium alloy AlSi10Mg was examined. Specific energy absorption was used to compare the two materials. The results show that micro-lattice structures made from stainless steel outperform the aluminium ones in energy absorption ability. The highest amount of absorbed energy was measured for BCCZ structure. This thesis describes the failure mechanism of micro-lattice structures and offers a complex evaluation of energy absorption for both materials.
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