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Mechanical properties of large scale 3D printed parts
Strela, Dominik ; Malý, Martin (referee) ; Křivohlavý, Petr (advisor)
This study focuses on the effects of printing parameters on mechanical properties of parts manufactured with FDM (Fused Deposition Modelling) technology. Specimens made from PLA material using the KUKA KR8 R1620 robotic arm underwent tensile test, their shape was designed so to prevent effects of negative phenomena on the results. The results were evaluated and graphically shown. The results show that inter-rastral bonds intensely weaken the parts strength, however a slight material overfill helps strengthen the bonds. The highest tensile strength was measured on specimens with the largest inter-rastral distance and layer hight, with 1,1 as the coefficient of material flow. The results of this study should serve as reference values for future research of properties and behaviours of parts printed using nozzles of larger diameter. They describe the impact of rasterizing products on the final strength.
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Study of the Chaboche´s plasticity model complexity influence on the stress and deformation at the high pressure vessel
Paraska, Boris ; Obdržálek, Vít (referee) ; Vrbka, Jan (advisor)
The main aim of this thesis is to define material parameters of Chaboche model of plasticity. Adjustment of the parameters has to correspond to the experimental datas. These datas are represented by an uniaxial strain controlled test curve for fewer than two cycles and also by cyclic stress-strain curve. After that, an cyclic tension-compresion test for various parameters of Chaboche´s model of plasticity is simulated in an ANSYS software. Finally, the most suitable configuration of Chaboche´s model of plasticity is used for cylindrical thick-walled body. Cylindrical body represents a simplified model of high-pressure tank of fuel (diesel) – rail in Common Rail system.
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Assessment of fracture risk for a langlauf ski made as a glass fibre reinforced sandwich
Láštic, Daniel ; Majer, Zdeněk (referee) ; Burša, Jiří (advisor)
The first part of bachelor’s thesis is devoted to basic theoretical knowledge about usage of sandwich theory of beams, which are made of different materials in the core and faces. This part includes brief description of composites (common car- rying component of sandwich structures) with emphasis put on the fibre compo- sites and laminates. A special characteristic of composites – orthotropy is men- tioned. The second part is focused on description of obtaining of elastic constants of materials used in the real cross-country ski by experiment, on stress calculation and fracture risk assessment in cross-country ski made as sandwich structure for the most adverse operational state. The solution is executed with the help of an- alytical formulas of mechanics of materials derived in this part. The problem is also solved using finite element method (FEM) employing ANSYS software.
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Static strength assessment of the weld
Gális, Róbert ; Řehák, Kamil (referee) ; Dlugoš, Jozef (advisor)
This thesis aims to review, summarize and compare the available approaches and standards assessing static strength of welds. In the introductory section, the theoretical knowledge required to assess static strength of welded structures is summarised. In the next section, the algorithms for evaluating static strength of welds using each guideline are reviewed and described in detail. They are also applied to designed T-shaped welded geometry with a two- sided fillet weld. Subsequently, the obtained results are compared and evaluated. Finally, an experiment is drafted to verify the calculations or to determine the most appropriate approach.
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Assessment of fracture risk for a langlauf ski made as a glass fibre reinforced sandwich
Láštic, Daniel ; Majer, Zdeněk (referee) ; Burša, Jiří (advisor)
The first part of bachelor’s thesis is devoted to basic theoretical knowledge about usage of sandwich theory of beams, which are made of different materials in the core and faces. This part includes brief description of composites (common car- rying component of sandwich structures) with emphasis put on the fibre compo- sites and laminates. A special characteristic of composites – orthotropy is men- tioned. The second part is focused on description of obtaining of elastic constants of materials used in the real cross-country ski by experiment, on stress calculation and fracture risk assessment in cross-country ski made as sandwich structure for the most adverse operational state. The solution is executed with the help of an- alytical formulas of mechanics of materials derived in this part. The problem is also solved using finite element method (FEM) employing ANSYS software.
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Study of the Chaboche´s plasticity model complexity influence on the stress and deformation at the high pressure vessel
Paraska, Boris ; Obdržálek, Vít (referee) ; Vrbka, Jan (advisor)
The main aim of this thesis is to define material parameters of Chaboche model of plasticity. Adjustment of the parameters has to correspond to the experimental datas. These datas are represented by an uniaxial strain controlled test curve for fewer than two cycles and also by cyclic stress-strain curve. After that, an cyclic tension-compresion test for various parameters of Chaboche´s model of plasticity is simulated in an ANSYS software. Finally, the most suitable configuration of Chaboche´s model of plasticity is used for cylindrical thick-walled body. Cylindrical body represents a simplified model of high-pressure tank of fuel (diesel) – rail in Common Rail system.
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