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Analysis of residual stresses in arterial wall
Novák, Kamil ; Fuis, Vladimír (referee) ; Burša, Jiří (advisor)
This thesis deals with computational modeling of the influence of residual stresses in idealized geometry of blood vessels and subsequent application of acquired knowledge to abdominal aortic aneurysm. In the terms of quality of the computational model, we reduced the uncertainties that are included in the computational model without considering the influence of residual stresses. The basic assumption of homogenization significant peaks of the stress between inner and outer vessel wall was met for each level of the computational model Methods that have been used are: deformation method (opening angle method), inverse mechanics of large deformations, fictitious temperature – for linear elastic material and hyperelastic material defined by the constitutive model. Numerical verification was carried out using program ANSYS.
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Evaluation of the machined surface and subsurface properties using Barkhausen noise analysis
Blažíček, Dominik ; Malec, Jiří (referee) ; Švejcar, Jiří (advisor)
Master thesis deals with the influence of milling to resulting surface integrity of gear tested by Barkhausen Noise Analysis technique. Two sets of gears milled by different machines by comparable parameters were used to solve the task. The testing of surface integrity was carried out after heat treatment and final grinding. It was experimentaly approved the effected surface/subsurface damage caused by milling remains in the material through the heat treatment. Based on these results, it can be assumed that different milling affects the resulting surface integrity after HT.
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Issue of Internal Tension in Materials during Machining of Thin-walled Components
Osička, Petr ; Chladil, Josef (referee) ; Sedlák, Josef (advisor)
This master thesis focuses on analysing the origins of residual stress in material caused by face milling. Representatives of three groups of aluminum alloys (5000, 6000, 7000) are compared by measurements. For measuring of the residual stress in aluminum alloys, the hole-drilling method was used by applying tensometric rosettes. In order to determine the influence of the used milling cutters', flatness of the machined surface was analyzed by comparative method. The thesis concludes with a discussion and an overall evaluation of the results.
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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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Analysis of possibilities of analytical approaches suitable for evaluating of stress-strain states of idealized aortic shapes
Turčanová, Michaela ; Burša, Jiří (referee) ; Novák, Kamil (advisor)
The bachelor's thesis deals with possibilities of analytical solution of stress-strain states of arteries. The first part of the thesis gives an information about cardiovascular system and continuum mechanics. The calculation was performed analytically and also numerically using ANSYS program. The analytical calculation was carried out considering non-linear theory of thin and thick-walled vessels involving the residual stress and fictitious temperature approach. Furthermore, the analysis of solutions of abdominal aortic aneurysms was done based on linear theory. Description of other methods of linear theory and techniques of calculating with residual stress are briefly summarized.
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Influence of setting and configuration of straightening machine on results of simulation of cross-roll straightening
Ščerba, Bořek ; Petruška, Jindřich (referee) ; Návrat, Tomáš (advisor)
Analytical methods or implicit finite element method (FEM) with beam elements to model straightened bar were used to analyze straightening process in multi-staggered cross-roll straighteners up to now. These are effective but require certain simplifications. Aim of this thesis is to create an explicit FEM model allowing usage of solid elements for circular bar without disproportional increase of computational time. This may lead to deeper understanding of the straightening process. The model is to be verified using straightening tables and then used to quantify influence of rollers configuration on results of the straightening process.
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