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Torsional stress fixture design using a universal testing machine
Kučík, Jiří ; Jaroš, Jan (referee) ; Vaverka, Ondřej (advisor)
This thesis aims to design a fixture for static torque testing for the Shimadzu AGX-V2 series universal testing machine. The fixture enables the mechanical conversion of linear motion to rotational motion and the securing of samples. The design includes the method of attaching the fixture to the machine, the geometry of the tested samples, and their fixation. The introductory part of the thesis provides a brief overview of possible motion conversion methods, the standardization of torque tests, and examples of several torque testing machines. The conceptual part focuses on designing variants of the fixture. Two variants are proposed: the first based on the principle of gears and the second on the principle of cams. These are compared using the finite element method. Based on the results, the fixture with the gear mechanism is selected, capable of torquing both solid and structured samples at an assumed maximum torque of 250 Nm. In the construction part, the final design of the mechanism is carried out and then verified using the finite element method and analytical strength calculations.
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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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Mediation in the Czech Republic
Jaroš, Jan ; Macková, Alena (advisor) ; Zahradníková, Radka (referee) ; Dörfl, Luboš (referee)
DISERTAČNÍ PRÁCE V ANGLICKÉM JAZYCE Mediation in the Czech Republic A doctoral thesis represents an evaluation of the fulfillment of the legislator's predicted objectives and expectations placed into the adopted legislation of mediation after ten years of its effectiveness in the legal system of the Czech Republic. The text is divided into thirteen chapters, which gradually address the main topics related to the new civil law regulation of mediation. The first chapter briefly describes the development and existing mediation regulation in the Czech Republic. Next, there are identified the main points of research interest, which are elaborated in more detail in the following chapters. The attention is successively paid to the topics of (i) the duplex legal regulation of mediation, (ii) the performance of mediation outside the framework of the Mediation Act, (iii) the presumed benefits and guarantees associated with mediation under the Mediation Act, (iv) confidentiality of the subjects involved in mediation, (v) the remuneration and reimbursement of the mediator's expenses, (vi) prerequisites for the registered mediator profession, (vii) special legislation for mediator-attorneys, (ix) regulation of the first ordered meeting with a registered mediator, (x) the statute of limitations, (xi) direct...
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Support of Mapping by Image Processing
Jaroš, Ján ; Herman, David (referee) ; Váňa, Jan (advisor)
This bachelor's thesis deals with methods of detection of selected objects in video and with importing these objects into OpenStreetMap central database based on their geographic location. It focuses mainly on recognition of road signs. First section briefly describes some of the most widely used methods and OpenStreetMap project itself. In the following chapters is given a more detailed overview of used methods of proposed system, its implementation and testing. The conclusion contains evaluation of whole work and the possible improvements are listed here.
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Development of 3D metal printing process parameters for producing of the lattice structure
Jaroš, Jan ; Koutný, Daniel (referee) ; Vrána, Radek (advisor)
Selective laser melting (SLM) in additive technology, which allows production of lattice structures. Lattice structures are very difficult to produce using conventional methods. The main use of lattice structures is in aerospace industry and medicine for bone implants production. In this work influence of processing parameters (laser power, scanning speed) on properties (diameter, surface roughness, porosity) of struts is investigated. The processing parameters selection was based on single tracks test. In the first test, ImageJ was used to determine porosity of struts. In the second test porosity was analyzed with more accurate µCT technology. Both tests used 3D scanning technology to determine dimension accuracy and surface roughness of samples. The measurement results led to the detection of processing parameter „window“ where samles had the best combination of surface roughness and porosity. The best results were achieved with 225-275 W laser power and scanning speed of 1400-2000 mm·s-1.
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The developement of SLM laser strategy for lattice structure fabrication
Jaroš, Jan ; Dočekalová, Kateřina (referee) ; Vrána, Radek (advisor)
Additive technology (AT) is increasingly used to design unique parts, mainly due to the ability to produce complex structures such as lattice structures. However, this also includes the need to modify the process parameters or the production strategy of the AT, which is usually set to produce volume geometry. Using samples corresponding to the geometries of the lattice structures, the exact input values were measured, which were used to design the SLM (Selective laser melting) production process using a contour strategy. Thanks to this, vertical and angled (35.26°) struts with low porosity (up to 0.2 %), low surface roughness and high dimensional accuracy were produced. Porosity was measured on µCT, surface roughness and dimensional accuracy were measured on STL data. The results show that if the parameters of the SLM process are set correctly, it is possible to produce struts with low porosity and surface roughness using different combinations of laser power and scanning speed. The above findings were used in the creation of script that allow the selection of suitable process parameters to produce lattice structures.
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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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Mediation in the Czech Republic
Jaroš, Jan ; Macková, Alena (advisor) ; Zahradníková, Radka (referee) ; Dörfl, Luboš (referee)
NÁZEV DISERTAČNÍ PRÁCE V ANGLICKÉM JAZYCE, ABSTRAKT V ANGLICKÉM JAZYCE A 3 KLÍČOVÁ SLOVA V ANGLICKÉM JAZYCE Mediation in the Czech Republic A doctoral thesis represents an evaluation of the fulfillment of the legislator's predicted objectives and expectations placed into the adopted legislation of mediation after ten years of its effectiveness in the legal system of the Czech Republic. The text is divided into two main sections. The first section deals with topics related to the Act on Mediation and the Decree on Examination and Mediator's Remuneration. The second part is concerned with the consequences and connections that are not explicitly regulated by such legislation. In the specific chapters, the expectations of the legislator and subsequent opinions arising from ten years of expert discussion are presented. The author's own conclusions formed using appropriate methodological procedures, especially analytical, normative and empirical approach follows. If possible, available statistical data and partly also foreign examples were used in the thesis. In the first part, the addressed topics are (i) the duplex legal regulation of mediation, (ii) the consequences of such duplexity, i.e. advantages and disadvantages for the mediator and participants, (iii) the performance of mediation according to the Trade...
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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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