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Application of the digital image correlation in the measurement of residual stresses by the hole-drilling method
Plucnar, Tomáš ; Horák, Richard (referee) ; Halabuk, Dávid (advisor)
The thesis focuses on the measurement of residual stresses using digital image correlation (DIC). The work describes residual stresses and also derives an analytical description of the deformation around a drilled hole, which is essential for evaluating the experiment. The largest part of the thesis is dedicated to the measurement and evaluation of residual stresses. Within the framework of the thesis, measurements of residual stresses were conducted for samples with pre-drilled holes and also for solid samples into which holes were drilled. These measurements were then used to evaluate the effects of various DIC software settings on the assessed residual stress. Measurements on samples with pre-drilled holes were used to determine the impact of the random pattern density and the influence of the camera on the evaluated residual stress.
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Numerical modelling of residual stress in metallic materials
Rakušan, Jakub ; Vosynek, Petr (referee) ; Hutař, Pavel (advisor)
The presented master thesis is focused on residual stresses, more precisely on the implementation of residual stresses in simulations using the finite element method (FEM), experimental determination of residual stresses and the influence of residual stresses on fatigue crack propagation. In this thesis, the found approaches of implementing residual stresses in FEM are tested and the most suitable of the tested approaches is then used in the simulation experiment. By comparing the FEM simulation and experimentally measured data determined by the modified slotting method, the residual stress values on an induction hardened railway axle specimen are determined. This is followed by the verification of the determined residual stress values by X-ray diffraction and the determination of the effect of residual stress on the rate of propagation of long fatigue cracks.
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Increasing of fatigue life of a ball pin using roller burnishing
Bastl, Václav ; Kolomý, Štěpán (referee) ; Zemčík, Oskar (advisor)
Bachelor’s thesis carried out in cooperation with THK Rhythm Automotive Czech a.s. is focused on the problematics of fatigue life of ball pins in a car‘s suspension. As an option of increasing this parameter, roller burnishing is the proposed technology of surface treatment on the ball pin. Rolling parameters are designed, and fatigue tests and evaluation of the measured values are performer on the subsequently modified pins.
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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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