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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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Design of pedal system for Pneumobil race car using topology optimisation
Pchálek, Václav ; Červinek, Ondřej (referee) ; Vaverka, Ondřej (advisor)
This thesis deals with design of pedal assembly of pneumobile racing car to increase its rigidity and reduce its weight. Based on the search, the kinematics of pedal was changed due to more precise determination of pedal ratio. Topology optimization and lattice structure were used to achieve the goals. The results were checked by strength analysis using finite element method. To produce topologically optimized parts use of metal additive technology is assumed, for which the parts have been further modified. Deformation was reduced by 13,4 % for the brake pedal and by 96,8 % for the accelerator pedal. The weight of the pedal system has been reduced by 31 %. This pedal assembly design could be an alternative to the current pedal assembly, as it is lighter and meets the requirements for higher rigidity.
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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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Design of auxetic structures for the selective laser melting technology
Pchálek, Václav ; Hutař, Pavel (referee) ; Červinek, Ondřej (advisor)
With the development of additive technologies, it became possible to produce auxetic structures with complicated geometries. Despite their intensive study, their potential for high resistance to local loading has not yet been explored. Describing this phenomenon and its causes would enable the effective design of structures with greatly enhanced resistance to foreign object impact. Therefore, this work investigated the deformation behavior of auxetic re-entrant honeycomb structures under local loading. The relationship between the resistance of the structure to local loading and the magnitude of the negative Poisson´s number, which was controlled by the geometry of the basic cell, was investigated. An analytical approach was used to determine the Poisson´s number of the structures. Subsequently, a prediction of the local loading behaviour of the structures was made using the finite element method assuming small and large deformations. This behavior was then experimentally verified for small and large strain rates on structures fabricated by selective laser melting technology. It was found that for the assumption of small deformations, the smaller the Poisson´s number of the structure, the more resistant it is to local loading. However, this does not apply to the assumption of large deformations, where the wall interaction and its buckling were difficult to predict. Furthermore, structures with thinner walls were shown to deform more, thus using their full deformation potential and therefore being more resistant to local loading. When tested at both low and high strain rates, a rearrangement of the structure towards the impact location was observed in two directions, perpendicular and against the direction of loading. It was found that structures with different geometry but the same Poisson's number have the same deformation behavior in terms of strain rate and reaction force. The findings of this work contribute to the understanding of the behaviour of auxetic structures under local loading, which can be used in the design of such loaded structures in specific applications.
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