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Design of a chamber for storing metal powders
Jeleček, Petr ; Červinek, Ondřej (referee) ; Koutný, Daniel (advisor)
Additive manufacturing from metallic materials is a continously evolving branch of the engineering industry, where correct material storage is a crucial aspect. The main objective of this bachelor’s thesis is to create a structural design of a chamber for storing barrels containing metal powders. A survey of commercially available storage systems highlighted a gap in the market, specifically of fully or partialy automated storage systems that could also be used in a laboratory environment. The conceptual designs are inspired by commercially available storage systems and include a new, unconventional solution. After the evaluation of conceptual designs a specific structural design was developed that met the project criteria. The final design enables storing barrels containing metal powders in an inert atmosphere and partialy automates the transport of barrels between the storage and the work space.
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Design of high-performance auxetic structure for energy absorption
Sobol, Vítězslav ; Hutař, Pavel (referee) ; Červinek, Ondřej (advisor)
Additive technologies enable the production of complex structures with high control over their geometric parameters. In the field of energy absorption, it is advantageous to use a structured material because they can safely absorb large amount of energy. For high-performance absorbers, it can be advantageous to use auxetic structures which, due to their unique internal geometry, provide, e.g. better energy redistribution. Compared to conventional structures, however, they do not achieve such high values of absorbed energy. Also, literature does not offer a detailed description of the mechanisms of absorbed energy increase, based on which the geometry of the auxetic structure could be effectively modified. This thesis dealt with the systematic design of the internal geometry of a 2D auxetic structure to increase the absorption performance. Five different arm geometries were tested as well as cells with reinforcements with stepped distance from the centre of the cell. Compression testing showed a low dependence of the arm geometry used and a significant benefit of the reinforcements on the energy absorbed. The DIC technology provided deformation maps of structures, which led to the clarification of the energy increase mechanism by the reinforcement implementation. The results obtained led to an auxetic structure that was able to absorb 70 % more energy per unit mass compared to the reference geometry.
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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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Topology optimization of a quadcopter arm using 3D print
Simon, Jakub ; Červinek, Ondřej (referee) ; Vaverka, Ondřej (advisor)
This bachelor thesis deals with the comparison of manufacturing constraints applied during topology optimization of a demonstration component, which was a quadcopter arm. Four designed arms were optimized, each with different manufacturing constraints: Extrusion, Single draw, Split draw, Overhang and one arm only with symmetry plane, without any other manufacturing constraint. For all designs, it was important to maintain a continuous geometry during optimization and that final weight approximately equals to the weight of the original arm. All five arms were then subjected to static structural analysis with the finite element method. After that, arms were printed using Fused deposition modelling (FDM) from ABS material and then tested by static force. The photogrammetry method was used to evaluate deformation. Results of the experiment were recalculated to relative stiffness, where small differences between weights were considered. Relative stiffnesses of designed arms were then compared, showing that 4 out of 5 topology optimized arms have higher stiffness than the original shape. The toughest design is without manufacturing constraints which at the same weight has 12.5 times higher relative stiffness than the original arm.
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Design of auxetic structures for the 3D print
Sobol, Vítězslav ; Škaroupka, David (referee) ; Červinek, Ondřej (advisor)
Behavior in which the material expands in one direction and in a perpendicular direction under tensile loading is called auxetic and is associated, e. g. with increased indentation resistance. Auxetic behavior is mainly due to the typical geometry of the internal structure. Therefore, it can be achieved by a unique arrangement of inner micro-lattice structure. Through additive technologies such as Selective Laser Melting (SLM), it is possible to manufacture such complex geometry. This bachelor thesis deals with the design of a spatial micro-lattice structure that will exhibit auxetic behavior and can be made by the SLM method. Based on an extensive research on the topic of 2D and 3D auxetic structures, a new type of auxetic structure was designed. The manufacturability was verified by making several samples in different dimensional configurations. Auxeticity and mechanical properties were subsequently tested using a drop test. By evaluating it, it was possible to determine the influence of dimensional parameters on the overall behavior of the structure.
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3D Lattice Structures for Application in Selective Laser Melting technology
Červinek, Ondřej ; Škaroupka, David (referee) ; Vrána, Radek (advisor)
Additive technologies allow manufacturing of components with very complex shapes which are difficult to manufacture with conventional technologies. Among these technologies belongs the Selective Laser Melting (SLM). Suitable applications of SLM include manufacturing of light-weight 3D structures like lattice structure or an organic geometry called gyroid. This bachelor thesis is focused on creation of models of gyroid structure and its application to parts followed by manufacturing with SLM. Series of models were made with mathematical software. Implicitly defined equation were used for better geometry coordination of created models. Options utilization and manufacturability of gyroid structures were tested within application into turbocharger impeller. At the end of this thesis was successfully manufactured the impeller including two types of gyroid structure (single-gyroid and double-gyroid)
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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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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 topologically optimized upright for pneumobil race car
Mende, Milan ; Červinek, Ondřej (referee) ; Vaverka, Ondřej (advisor)
This thesis deals with the design of lightweight front uprights of pneumobile Javelin using topology optimization, followed by manufacturing by additive technology Selective Laser Melting. Aluminium alloy AlSi10Mg was used. Topology optimized parts should have met the requirement of minimal safety factor equal to 2, therefore the stress strain analysis was performed using FEM. The maximal deformation was determined and the safety factor obtained. Two unsymmetrical uprights were designed due to parameters of the brake system. The precision of manufacturing was verified by optical digitization. Machined uprights were mounted on the pneumobile and tested directly on the vehicle. No limit states were observed during testing and subsequent races, so they proved to be fully functional. Weight of the left upright was reduced from 1 609 g to 758 g, the right one was lightened to 741 g.
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