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Optimalization of Exhaust Manifold for Škoda 1,2 MPI
Kubiš, Milan ; Ramík, Pavel (referee) ; Beran, Martin (advisor)
The subject of this diploma thesis is optimalization of exhaust manifold of ŠKODA 1,2 MPI engine with respect for the plastic deformation at heat stress. The first part is focused on general description of converter module, whose component the exhaust manifold is. In the next part of the thesis is computation of a heat load of the exhaust manifold. The last part is devoted to the seal analysis of the whole converter module of a ŠKODA three-cylinder engine.
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Deep learning methods for acoustic emission evaluation
Kovanda, M. ; Chlada, Milan
The goal of this paper is to show the possibilities of state-of-the-art deep learning methods for ultrasound signals evaluation. Several neural network architectures are applied to\nacoustic emission signals measured during the tensile tests of metallic specimen to determine the beginning of plasticity in the material. Plastic deformation is accompanied by microscopic\nevents such as a slip of atomic plane dislocations which is hardly detectable by other methods. The potential of machine learning is demonstrated on two tensile tests where the material is\nstrained until it collapses. The examined networks proved well to reliably predict the risk of collapse together with changes in the ultrasound emission signals.
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Study of cooperative dislocation phenomena in solids by the acoustic emission technique
Knapek, Michal ; Chmelík, František (advisor) ; Haušild, Petr (referee) ; Landa, Michal (referee)
Title: Study of cooperative dislocation phenomena in solids by the acoustic emis- sion technique Author: Michal KNAPEK Department: Department of Physics of Materials Supervisor: doc. RNDr. František Chmelík, CSc., Department of Physics of Materials Abstract: Plastic deformation of micron-scale crystalline materials differs con- siderably from bulk specimens, as it is characterized by random strain bursts. Three categories of metallic samples were investigated in this thesis: micron- scale copper micropillars with varied geometries, submillimeter-scale aluminum microwires, and aluminum and aluminum-magnesium salt-replicated foams. Very precise fabrication methods and sensitive measurement set-ups consisting of uni- axial compression and tensile tests with concurrent acoustic emission (AE) record- ing were developed. These fine methods allowed for investigations of effects re- lated to plastic deformation at micrometer scales, i.e. the dislocation dynamics associated with the stress drops. Size effects in plastic deformation, as well as clear correlations between the stress drops and the AE events, were found in mi- crosamples, confirming that dislocation avalanches are indeed responsible for the stochastic character of deformation processes also at microscales. Open-cell pure aluminum and aluminum-magnesium...
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Production of high pressure hydraulic filter housing
Podloucký, Lukáš ; Lidmila, Zdeněk (referee) ; Císařová, Michaela (advisor)
The Bachelor’s thesis is focused on solving the problem of production of high-pressure hydraulic filter by cold extrusion technology. The initial semi-finished product is a C15R steel cap with a diameter of 104 mm and a height of 57.9 mm. The production series assumes a quantity of 30,000 pieces per year. The technologicality of the product evaluation was based on technical literature knowledge and professional experience. The technological process was chosen subsequently. This process counts with the extrusion in two operations with mid-operational recrystallization annealing and with the use of surface treatment by phosphating and soaping. An Eitel 1 250 press with a nominal forming force of 12 500 kN is designed for the production. The design of the forming tools takes into consideration the shape of the extrusion, technological principles and mathematically verified safety. The material of the die and punch is high-speed tool steel 19 830. The material of the ejector it is high-alloy tool steel 19 437. The technological process and force calculations are verified by simulation of the forming process created in the Simufact Forming program.
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Study of cooperative dislocation phenomena in solids by the acoustic emission technique
Knapek, Michal ; Chmelík, František (advisor)
Title: Study of cooperative dislocation phenomena in solids by the acoustic emis- sion technique Author: Michal KNAPEK Department: Department of Physics of Materials Supervisor: doc. RNDr. František Chmelík, CSc., Department of Physics of Materials Abstract: Plastic deformation of micron-scale crystalline materials differs con- siderably from bulk specimens, as it is characterized by random strain bursts. Three categories of metallic samples were investigated in this thesis: micron- scale copper micropillars with varied geometries, submillimeter-scale aluminum microwires, and aluminum and aluminum-magnesium salt-replicated foams. Very precise fabrication methods and sensitive measurement set-ups consisting of uni- axial compression and tensile tests with concurrent acoustic emission (AE) record- ing were developed. These fine methods allowed for investigations of effects re- lated to plastic deformation at micrometer scales, i.e. the dislocation dynamics associated with the stress drops. Size effects in plastic deformation, as well as clear correlations between the stress drops and the AE events, were found in mi- crosamples, confirming that dislocation avalanches are indeed responsible for the stochastic character of deformation processes also at microscales. Open-cell pure aluminum and aluminum-magnesium...
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Verification of the properties crimp joint
Horák, Ondřej ; Hruška, Ondřej (referee) ; Lidmila, Zdeněk (advisor)
The bachelor thesis deals with the description of mechanically unbreakable conections, called crimp connection. The most often used materials are copper, brass and bronze. The crimp connections are divided into joints with an open tube, closed tube and crimp isolation. The joint is formed by bending of the parties of the crimp, where a consequent plastic deformation results in a mechanically non-detachable joint. The post production control of the crimp consists of visual inspection, measure of the crimp height, supplementary tearing test and cutting the crimp. No visual defect in testing two types of crimp connections was detected. The measured crimp height corresponds to the values specified by the manufacturer. During the tear test, the desired values were not achieved by incorrectly attaching the wire to the clamping mechanism and no manufacturing defects were detected at the final check of the cut.
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Study of cooperative dislocation phenomena in solids by the acoustic emission technique
Knapek, Michal ; Chmelík, František (advisor) ; Haušild, Petr (referee) ; Landa, Michal (referee)
Title: Study of cooperative dislocation phenomena in solids by the acoustic emis- sion technique Author: Michal KNAPEK Department: Department of Physics of Materials Supervisor: doc. RNDr. František Chmelík, CSc., Department of Physics of Materials Abstract: Plastic deformation of micron-scale crystalline materials differs con- siderably from bulk specimens, as it is characterized by random strain bursts. Three categories of metallic samples were investigated in this thesis: micron- scale copper micropillars with varied geometries, submillimeter-scale aluminum microwires, and aluminum and aluminum-magnesium salt-replicated foams. Very precise fabrication methods and sensitive measurement set-ups consisting of uni- axial compression and tensile tests with concurrent acoustic emission (AE) record- ing were developed. These fine methods allowed for investigations of effects re- lated to plastic deformation at micrometer scales, i.e. the dislocation dynamics associated with the stress drops. Size effects in plastic deformation, as well as clear correlations between the stress drops and the AE events, were found in mi- crosamples, confirming that dislocation avalanches are indeed responsible for the stochastic character of deformation processes also at microscales. Open-cell pure aluminum and aluminum-magnesium...
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Titanium and titanium alloys prepared by cryogenic milling
Kozlík, Jiří ; Stráský, Josef (advisor) ; Janeček, Miloš (referee)
Ultra-fine grained materials are presently thoroughly investigated due to their enhanced mechanical properties. Cryogenic milling is one of the severe plastic deformation methods, which allow production of these materials. Titanium powder was processed by cryogenic milling in liquid nitrogen and argon and consequently consolidated via spark plasma sintering method. In this work, the influence of milling conditions (liquid nitrogen vs. liquid argon, material of balls, duration and speed of milling, usage of stearic acid) on size and shape of powder particles, contamination and mechanical properties was investigated. Particle size reduction was generally not observed, while their morphology changed significantly. Using liquid nitrogen as a cooling medium leads to strong contamination of prepared material and consequently to its hardening and embrittlement. Stearic acid supresses cold welding of particles during milling and enhances its efficiency. It is possible to eliminate stearic acid from powder by cleaning in acetone before sintering, to prevent contamination of processed material. Microhardness increased, depending on milling efficiency (in liquid argon), from original 178 HV to 200-300 HV range. Increase of yield and ultimate stength was observed in compression tests while maintaining ductility....
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Study of cooperative dislocation phenomena in solids by the acoustic emission technique
Knapek, Michal ; Chmelík, František (advisor)
Title: Study of cooperative dislocation phenomena in solids by the acoustic emis- sion technique Author: Michal KNAPEK Department: Department of Physics of Materials Supervisor: doc. RNDr. František Chmelík, CSc., Department of Physics of Materials Abstract: Plastic deformation of micron-scale crystalline materials differs con- siderably from bulk specimens, as it is characterized by random strain bursts. Three categories of metallic samples were investigated in this thesis: micron- scale copper micropillars with varied geometries, submillimeter-scale aluminum microwires, and aluminum and aluminum-magnesium salt-replicated foams. Very precise fabrication methods and sensitive measurement set-ups consisting of uni- axial compression and tensile tests with concurrent acoustic emission (AE) record- ing were developed. These fine methods allowed for investigations of effects re- lated to plastic deformation at micrometer scales, i.e. the dislocation dynamics associated with the stress drops. Size effects in plastic deformation, as well as clear correlations between the stress drops and the AE events, were found in mi- crosamples, confirming that dislocation avalanches are indeed responsible for the stochastic character of deformation processes also at microscales. Open-cell pure aluminum and aluminum-magnesium...
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The Issue of Shot Peening
Lánc, Kryštof ; Daněk, Ladislav (referee) ; Peterková, Eva (advisor)
The thesis is primarily focused on theoretical processing shot peening technology, which belongs among the finishing operations using plastic deformation. The thesis is primary focused on describing basic principle of shot peening, sorting shot peening machines and abrasives, the principle of optimization of controlled shot peening and the related tests. The document also contains a methodology of creating educational material for operators of shot peening machine.
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