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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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Fatigue properties of materials prepared by SLM method
Hanáček, Josef ; Pantělejev, Libor (referee) ; Štěpánek, Roman (advisor)
This work deals with description of SLM (Selective Laser Melting) method, which is one of ALM (Additive Layer Manufacturing) method. In first part the general laws of fatigue and SLM method are described. The second part deals with the influence of processing parameters to final properties of material. The main goal of work is to determine dependence between processing parameters and mechanical properties of SLM processed components. Special attention is dedicated to fatigue properties.
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Resonance and damping behavior of lattice structures produced by Selective Laser Melting
Lagiň, Adam ; Čížek, Petr (referee) ; Koutný, Daniel (advisor)
In reaction to the uptrend of additive manufacturing of lightweight structured metallic parts, this diploma thesis is focused on the resonant and damping behavior of micro-truss lattices produced by Selective Laser Melting (SLM) technology. Micro-truss structures already found usage in various types of optimizations. Therefore, the optimization of resonance or damping could be also assumed as possible. For this purpose, several finite element analysis approaches were used, including the referent solid element model and simplified beam models. Obtained results were verified experimentally via pulse modal analysis. Material and mechanical properties of samples for FEA results and experimental results comparison were unified through secondary experiments. The main goal of this research was to explore the behavior of resonance and damping of structures when their elementary parameters are changed. The results from both, numerical and experimental approaches confirm that the eigenfrequency and the damping ratio of the structure can be affected by the change in the truss diameter, cell size, or type of structure. The work also presents the successful methods for simplified beam model optimization, which guarantees its high precision in the wide field of tested samples. This newly obtained knowledge creates a comprehensive overview of micro-truss structures, which can be used for the conscious design of ultra-light parts with the required eigenfrequency and damping ratio.
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Design of support structures for parts made of Inconel 718
Kuhajdik, Matej ; Hutař, Pavel (referee) ; Koutný, Daniel (advisor)
This master thesis deals by the design of support structures for the production of parts made of nickel superalloy IN718 using selective laser melting (SLM). The aim of this work is to design a support structure so that technological problems (excessive deformation of the part due to high residual stresses and insufficient heat dissipation) are eliminated and replace the use of massive volume support, which is inefficient in terms of design and production time, consumed material and postprocessing. Mechanical behaviour of residual stresses of built component, design points of selected support structures (perforated block with pins, BCCZ with perforated contour) and design recommendations were quantified by using thermo-mechanical simulations of production and series of experiments. The functional sample was tested by designing specific support structures for the turbine wheel with subsequent production. The support structure ensured safe, successful production without potential problems and met the requirement to minimize material consumption through effective large-scale perforation of the structure.
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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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Geometric Accuracy of Additively Manufactured Test Parts
Ilčík, Jindřich ; Sehnoutka, Petr (referee) ; Koutný, Daniel (advisor)
The presented diploma thesis deals with the control of the geometric accuracy of the parts produced by additive manufacturing technology selective laser melting. The paper first analyzed the work of the other authors dealing with this issue. Based on obtained informations from this analysis were developed benchmark test parts for quality control of production on a commercial machine SLM 280 HL supplied by SLM Solutions GmbH. The work was carried out several tests to determine the appropriate parameters of construction parts. These tests, their results and conclusions are fully described in this papper.
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Structural optimization of the heat switch part
Zemek, Albert ; Mašek, Jakub (referee) ; Löffelmann, František (advisor)
This diploma thesis deals with the design of a structure for heat transfer path of miniaturized heat switch. The focus is on production using SLM additive technology. The aim is to assess the possibilities of using metal 3D printing on a part intended primarily for heat transfer. This work presents several concepts of structure arrangement, which are further analysed and evaluated. The results show the potential of additive technologies in this area and the proposed structures meet the heat transfer requirement according to the calculations used.
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Design of fast magnetorheological damper piston group using selective laser melting technology
Vítek, Petr ; Růžička, Bronislav (referee) ; Strecker, Zbyněk (advisor)
The diploma thesis deals with the development of the magnetic circuit of Magnetoreological (MR) dampers with a short time response. To achieve a short response time, a shape approach was chosen whereby the geometry of the magnetic circuit was chosen to significantly eliminate the occurrence of eddy currents. The influence of structures on magnetic properties was first examined on a simpler toroidal core and then the optimization was subjected to the magnetic circuit of the MR damper itself. Geometry optimization was done using FEM simulations. The resulting geometry was made of pure iron using Selective Laser Melting technology (SLM). In addition, a MR damper was completed and its properties on air and with MR fluid were measured, which were then compared with previously developed rapid MR dampers. It has been found that the newly designed magnetic circuit achieves similar time responses as all other compared fast MR dampers and reaches a higher dynamic range than most of the compared variants. The proposed magnetic circuit also has a significantly reduced weight.
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The use of small punch tests for materials with a higher level of structural inhomogeneity
Gordiak, Michal ; Řehořek, Lukáš (referee) ; Válka, Libor (advisor)
Master's thesis deals with evaluating applicability of correlation relationships between material characteristics determined by Small Punch Test and standard tensile test for material AlSi7Mg0,6 manufactured by casting and technology SLM. Results of Small Punch Tests are correlated with yield strength, tensile strength, elongation, and Young's modulus of elasticity. For each material characteristic various correlation methods are compared, while for each method corresponding coefficients are determined. Consequently, the applicability of individual methods is evaluated by substituting coefficients determined by various studies. Primarily analyzed are correlation methods for which future normalization is expected. The results of master's thesis show that structural inhomogeneity caused by SLM process does not result in high inaccuracies in determining material characteristics. Larger impact on material characteristics has high porosity, which was identified in cast material and led to significant deviations in evaluating tensile strength and elongation.
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The mechanical properties of AlSi9Cu3 aluminum alloy processed by SLM technology
Koutný, Filip ; Skřivánková, Vendula (referee) ; Paloušek, David (advisor)
This bachelor thesis aims to compare mechanical properties of cast AlSi9Cu3 aluminium alloy with its state after processing by the selective laser melting (SLM) technology. The theoretical part of this work presents general characteristics of aluminium alloys, focusing on their classification, mechanical properties and heat treatment as well as SLM technology processing. In the second part, we further discuss optimal processing parameters of the SLM 3D printing technology and compare mechanical properties of the conventionally cast AlSi9Cu3 alloy and the alloy processed by the SLM technology.
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