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Proposal of a new type of steam turbine blade attachement
Vrbický, Jiří ; Petruška, Jindřich (referee) ; Polzer, Stanislav (advisor)
This thesis describes design of new circumferential blade attachment on last grade of steam turbine and following stress-strain analysis by FEM with static and cyclic loading. It was created two new design of geometry, which were created based on existing and operating constructional solution of oblique double T blade attachment. It was made stress-strain FEM analysis on original design of blades. Its results served to realize change of construction. Their target was increase load capacity and service life of new types of blade attachment.
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Removal of residual stress in thin sheets by tension leveling
Dymáček, Martin ; Návrat, Tomáš (referee) ; Petruška, Jindřich (advisor)
Tension leveling is a process used in the steel industry in order to eliminate any shape imperfections of cold-rolled thin strips. The master thesis deals with developing a computer program that generates basic parameters of tension leveling line. The theoretical part of the thesis summarizes the types of the shape imperfections in strips, their causes and the principles of their elimination. This part also presents the mechanism of tension leveling and describes the present-day design of tension levelers. The practical part of the thesis starts with an analytical description of stress-strain behaviour of strip during tension leveling (supposing the simplified conditions). A computer program that allows devising basic parameters of tension leveling line is created on the basis of these analytical relations. The program results are successfully verified by numerical model based on the finite element method (FEM) created in the program ANSYS. Then the interdependencies of certain input and output parameters of created program are determined. These interdependencies can be used as effective design of tension leveling lines.
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Effect of Velocity of Impact Loading to Stress, Deformation and Durability of Component of Fuel Car System
Dobeš, Martin ; Horyl, Petr (referee) ; Návrat, Tomáš (referee) ; Petruška, Jindřich (advisor)
Passive safety is a well-known term. This term can be further categorized into different topics of the car passive safety, restraint systems, safety assistants (ABS, ESP, ASR, etc.). One of these topics is passive safety of the fuel system. Safety and tightness of the fuel system must be guaranteed even under non-standard conditions, for example a collision against a fixed obstacle. This issue is not often mentioned in the field of car safety. It is considered a standard. Passive safety of the fuel system is often ensured using various interesting technical solutions and devices, usually patented ones. The development of these solutions is supported by numerical simulations in different stages of development process. The doctoral thesis deals with impact loading of the plastic components of the fuel system, in particular Fuel Supply Module (FSM), which is mounted inside the fuel tank. The flange is the most important part of the fuel supply module from the car safety point of view. The flange closes FSM on the external side of the fuel tank. The thesis focuses on the finite element analysis of the complete or partial FSM, and the flange itself during impact loading. The main objective of this thesis are numerical material models, taking into account important aspects of the mechanical behavior of polymer materials during impact loading. There are a lot of ad hoc invented or standardized experiments described in this thesis. These experiments are used for estimation of the material parameters or comparison of numerical analysis vs real conditions, or tests. The solver LS-DYNA was mainly used for numerical simulations. The final results of this thesis brings new quantified knowledge about behavior of the Typical Semi-Crystal Polymer (TSCP), not only for impact loading. The practical part of this thesis defines new methodology for the numerical simulation approach of impact loading for FSM. This methodology is directly usable for new product development. A lot of numerical material models were developed and tested. The best results were achieved using numerical material model *MAT_24 with combination of *MAT_ADD_EROSION card. The limits and parameters for this numerical material model was estimated empirically during conducting experiments. The numerical material model SAMP-1 was partly solved in this doctoral thesis, but more detail study will be given in future works.
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Stress - strain analysis and creep assessment of the thick-walled tubular structures.
Zouhar, Michal ; Petruška, Jindřich (referee) ; Hlavoň, Pavel (advisor)
This thesis deals with the stress-strain analysis of thick-walled pipe parts. The dimension series (characterized by the D/d ratio) of three components are solved, then a direct tube, a torus with constant wall thickness (arcus) and a torus with variable wall thickness (bend). At first, the internal pressure amount, when a fully plastic state for these components is created, is solved. The amount of the limit pressure is determined analytically, numerically and by appropriate normative relations. The results and stress diagrams of individual solutions are mutually compared. Furthermore, these components are solved in the creep and are exposed to the maximum allowable normative internal pressure for 200,000 hours according to the standard – the operating time of components. The place of the maximum equivalent creep strain and the place of the maximum equivalent stress is examined. In these places the principal stresses are depicted depending on the D/d ratio. The results and stress diagrams of individual dimension series are mutually compared. From the available literary sources the condition of the limit state reach is chosen, according to which the evaluation of the limit state reach for individual components is carried out.
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Application of ductile fracture models in computational simulation of manufacturing operations
Hůlka, Jiří ; Houfek, Lubomír (referee) ; Petruška, Jindřich (advisor)
This diploma thesis is an introduction to the ductile fracture under large plastic deformations and is focused to numerical simulation of this type of problems. Explicit finite element method (FEM) is discussed in theoretical introduction as the most powerful tool for numerical calculations in this area. Actual state of research and possibilities of ductile fracture simulations are presented. Applicable fracture criteria are collected in a summary sheet and the most important ones are selected and commented in detail. The problem of implementation of selected criteria into commercial FEM packages is discussed, too. Main part of the work is presented in chapters 7÷9 where two ductile fracture criteria (Equivalent Fracture Strain and Johnson-Cook) are applied to numerical simulation of material cutting. All results were obtained with ABAQUS/Explicit 6.5.1 and their verification was realized by experimental measurement.
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Computational simulation of leveling of non-circular rods
Stráník, Radim ; Návrat, Tomáš (referee) ; Petruška, Jindřich (advisor)
This bachelor’s thesis illustrates the principle of straightening rolled through long table roll straightening machines using repeated plastic deformation, based on Eulerian description of the material flow. Thesis describes the program on computational simulation process straightening rods and extends it an easy to use input module for entering non-circular cross-section rods. At the end of the discussion also introduces the optimal settings for all input parameters to achieve best results.
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