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Defects and properties of heavy castings
Sobotka, Petr ; Carbol, Zdeněk (referee) ; Záděra, Antonín (advisor)
A diploma thesis was objected to a figure analyzing and a figure interpretation of ingot processing. The described figures were obtained from samples which were taking from feeder-heads of ingot of lower ram, produced in Vitkovice Machinery Group. The thesis was focused on ingot solidification and segregation processes which were associated with this procedure. The figures obtained from numeric simulation of ingot solidification in defined places were analyzed using statistic method – linear regression, as well as linear regression was used for evaluation of explored samples, their chemical compositions and mechanical properties. In conclusion all acquired results were summarized.
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Part Manufacturing by Using Hydroforming and Its Optimization
Chrz, Jan ; Jopek, Miroslav (referee) ; Řiháček, Jan (advisor)
The thesis presents an analysis and optimization of the manufacturing process of a part using the technology of parallel hydroforming. Two circular blanks made of DC01 steel with a thickness of 1 mm serve as a semi-manufactured part. In one of the blanks, the supply of the forming medium is constructed using Flowdrill technology. Subsequently, the two blanks are laser welded together and then formed. Numerical simulation using PAM-STAMP software was used to analyse the manufacturing process. This analysis provided information on wall thinning, deformation size, critical points on the product and springback. The numerical simulation was verified on the basis of comparison with an experiment. The criterion for verification was the course of the thickness of the part. Based on the results of the simulation, an optimization is performed in the thesis. It consists in determining the minimum required pressure of the forming medium for pressing the part, particularly for different distances between the two formed sheets.
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Numeric simulation of surfacing turbine rotors pinot pins
Tkaný, Jan ; Mrňa, Libor (referee) ; Daněk, Ladislav (advisor)
The master´s diploma thesis elaborated as the master's degree M-STG Manufacturing Technology solves surfacing problems in the simulations of surfacing turbine rotors pinot pins. The work was seen as a preparatory work before the real surfacing. Topic commissioned by Siemens Industrial Turbomachinery Ltd. For welding plates test has been used the method of SAW and the base material was identical to turbine rotor material, X22CrMoV 12-1. Additional material was Fluxocord 42. Simulations were carried out in programs SYSWELD and Visual - WELD. The output of the simulation software are temperature and stress fields, material structures and creations of the CCT diagrams at the base material, filler material, and mixed area.
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The influence of internal thermal storage mass used in passive houses' construction systems on their summer thermal stability
Němeček, Martin ; Hraška,, Jozef (referee) ; Katunský,, Dušan (referee) ; Kalousek, Miloš (advisor)
In recent years we may observe a growth in construction of passive houses and low energy houses using lightweight constructions such as modern wooden houses. It is assumed that wooden houses keep overheating more comparing to brick houses during summer period. Due to the lack of research in this field the paper investigates the influence of internal thermal storage mass in passive houses constructions on their summer thermal stability under the Czech climatic conditions. Only sensible heat accumulation without a usage of phase change materials is examined. Differences between wooden houses comparing to brick-built houses are emphasized. Objects of research are mostly residential passive houses in low energy building standards. However, the results of research might be applied to different types of buildings as well. The first section outlines theoretical fundamentals. For the research itself various scientific research methods were used, such as basic mathematical calculations, experimental temperature measurement of two buildings (detached house in Dubňany and in Moravany) and numerical simulations. Own tribute to the research was first of all discussion on the topic of thermal accumulation and structures heat capacity calculation. Experimental measurements outlined conclusive evidence about the importance of internal thermal storage mass in respect of interior summer overheating. The research confirmed that the highest interior temperature reached is mostly influenced by solar gains through unshaded windows. However, the influence of internal thermal storage mass is not remote. If we compare standard timber-framed wooden house to the hole ceramic bricks-built house, the wooden house will overheat by 0,5°C more during a standard day. Wider spread in the maximum temperature reached was measured for lightweight consturctions wooden houses without any internal thermal storage mass. Therefore, such structures should have an additional layer of thermal storage mass.
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Design of gating systems for wax patterns manufacture by numerical simulation
Vaščák, Tomáš ; Kolda, Vlastimil (referee) ; Horáček, Milan (advisor)
Diploma thesis deals with problem of designing the gating systems for wax patterns manufacture by numerical simulation. It was created an optimum numerical simulation of wax blend injection, optimized for a simple test model and then applied to more complex pieces. Based on knowledge of plastic injection and the simulation was designed several gating systems for mass-produced pieces. These findings were subsequently applied in the design of gating systems to produce large and thin wax patterns. By comparing the various proposals were finally selected the best solution in order to verify the optimum numerical simulation in practise.
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Analysis of the Production Processes Influence on Rail Deformations
Skalník, Vít ; Podaný, Kamil (referee) ; Vaněk, Mojmír (advisor)
The aim of this work is to assess the possibilities of using numerical simulation tools in the process of laser welding of the guide rail of a car seat. In the diploma thesis, a description of the components and the problem, which consists in the deformation of the groove of the guide rail, was made. A description was made of the manufacturing operations that the components go through. The positives of selected welding methods were evaluated and the choice of those used in production was justified. A description of the issues of laser welding, deformation and the use of simulation tools was made. The influence of individual production operations was evaluated in terms of the size and nature of deformations. Using the Visual – Mesh, Visual – Weld and Visual – Assembly simulation tools, which are products of the French company ESI Group, the same state of the simulated and real process was achieved. Subsequently, a proposal for the elimination of deformations and its verification using a simulation tool could be approached. The use of a spacer wedge, which acts on the most deformed places of the groove, was proposed. By its application, the resulting deformations were eliminated or significantly reduced. In the last part of the work, a technical and economic evaluation was made, taking into account the current global crisis and the important role of the automotive industry.
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Stress-strain analysis of the thin wall structure subjected to impact load
Tatalák, Adam ; Peč, Michal (referee) ; Návrat, Tomáš (advisor)
This master thesis deals with stress-strain analysis of simplified model of the thin wall transformer case subjected to impact load of electrical blast. Electrical blast is replaced by chemical blast (detonation of high explosive). The problem is solved using computational modeling utilizing the Finite Element Method (FEM) and LS-DYNA solver. After the introduction where detonation and shock wave propagation is explained the analytical approach is presented. This approach serves to results verification. In the next chapter is conducted research of applicable methods from which ALE method is chosen. In preliminary study is performed the mesh size analysis that is focused on finding the size of element which is both computational effective and gives accurate results. Next the infulence of input conditions (shape, location and parametres of high explosive, location of detonation point, boundary conditions) on distribution and time progress of pressure is investigated. Then influence of the opening on upper side of the case on overall pressure redistribution and strain and stress of the case is analysed. The stress-strain analysis of the case´s door which are connected to case by various types of contact models is performed as well as stiffness analysis of these types of contact.
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Analysis of Material Flow During Cam Forging
Kopečný, Adam ; Lidmila, Zdeněk (referee) ; Řiháček, Jan (advisor)
The diploma thesis deals with the optimization of final position of overlaps on a forged cam. This part is manufactured in Šroubárna Kyjov, spol. s r.o. The cam is made from ČSN 14 109 (100Cr6) steel. The thesis is focused on the optimization of overlaps arising due to pressed burrs on the edges of the semifinished forging. Currently, the final position of these overlaps is very close to the edge of the pre-forged hole of the cam. Undesired chipping of material occurs during machining of the hole to the exact dimension. The final position of the overlaps is optimized by using the numerical simulation in Simufact Forming 15.0, including a verification simulation for optimal parameter settings. Various diameters of semifinished products, turned tools, and modification of shapes of the tools are tested in the thesis to prevent occurrence of the overlaps in undesired positions.
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Optimization of gating systems (their yield) in Al castings made by investment casting technology
Žižka, Jiří ; Šmatelka, František (referee) ; Horáček, Milan (advisor)
This diploma thesis deals with the optimization of gating systems of shape-complex aluminum castings produced by investment casting process. Two castings whose massive gating systems make problem with the use of liquid metal (so called yield) were chosen for optimization. Each casting is described in its own chapter. The individual subchapters deal with description of the original and newly designed gating system. Simulation, test castings, X-ray inspection and metallographic examination were performed for each variant. At the end of each chapter there is an evaluation of the results of the optimization of gating system.
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Prediction of mechanical properties of lamelar iron castings by means of numerical simulation
Filipek, Szymon ; Hrouzek, Petr (referee) ; Roučka, Jaromír (advisor)
The aim of this thesis was to assess the degree of conformity between the mechanical properties evaluated by numerical simulation in software MAGMA5 and the measured values of hardness and ultimate tensile strength of lamellar graphite iron castings. The theoretical part of this thesis deals with the classification of cast iron, structural components of lamellar graphite iron, and the factors defining the resulting mechanical properties of the material. The practical part presents an attempt to find empirical dependencies between input parameters and results evaluated by simulation software. At the end, an analysis of the correlation between reality and simulation software is performed.
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