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Fatigue properties of weathering steel
Zavadilová, Petra ; Věchet, Stanislav (referee) ; Kunz, Ludvík (advisor)
This work deals with the influence of atmospheric corrosion on high-cycle fatigue properties of a weathering steel ATMOFIX B. New experimental data on fatigue strength of a steel exposed for 20 years to an atmospheric corrosion were compared to those characterizing the base material. Reduction of the fatigue lifetime of the exposed material compared with the base material was predicted on the basic of fractographic examination of fracture surfaces and the influence of surface notches on fatigue strength. The predicted results agree well with the experimental results.
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Usage of Rich Bottom Layers
Simkovič, Lukáš ; Hegr, Zdeněk (referee) ; Hýzl, Petr (advisor)
The aim of this diploma thesis is theoretical knowledge of the problems rich bottom layer and practical part of comparison of three asphalt mixtures for base layers using common road bitumen and modified rubber granulate. Selected functional laboratory tests (low temperature, fatigue resistance, bulk density) and stiffnes modules are performed on these mixtures and the results are compared to each other.
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Optimization of Machining Technologies for Special Applications
Ohnišťová, Petra ; Maňková, Ildikó (referee) ; Neslušan, Miroslav (referee) ; Píška, Miroslav (advisor)
This thesis is focused on the optimization of the milling technologies for special applications with respect to the required fatigue properties of aircraft components. The theoretical part of the thesis describes in detail the key features of the high-speed and high-feed milling, surface integrity after milling and fatigue characteristics of the studied component. The key aim of the work is devoted to the analysis of the influence of the cutting conditions of the high-speed peripheral and high-feed face milling of the bottom wing panel from aluminium alloy 7475-T7351 on the surface integrity in relation to the final fatigue properties. Therefore, the part of the work is a study of metallographic structure of the material, measurement of the accompanying machining phenomenon and quantities, advanced analysis of the surface integrity (amplitude characteristics, S-N parameters), manufacturing of the highly accurate fatigue samples and fatigue testing. Furthermore, the development of sample damage during in situ tensile loading and the development of sample damage during cyclic in situ fatigue tensile loading is also studied. The achieved results and fractography of fracture surfaces show that the studied cutting conditions have a significant effect on the quality of machining and resistance to mechanical stress, but they are not a decisive factor in terms of the fatigue crack nucleation. The effect of the achieved topography for the studied cutting conditions is suppressed by the presence of large intermetallic inclusions (Al7Cu2Fe; Al-Cr-Fe-Cu-Si) with a size from 2 µm to 20 µm, being the origin on the fatigue crack nucleation.
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Usage of Rich Bottom Layers
Simkovič, Lukáš ; Hegr, Zdeněk (referee) ; Hýzl, Petr (advisor)
The aim of this diploma thesis is theoretical knowledge of the problems rich bottom layer and practical part of comparison of three asphalt mixtures for base layers using common road bitumen and modified rubber granulate. Selected functional laboratory tests (low temperature, fatigue resistance, bulk density) and stiffnes modules are performed on these mixtures and the results are compared to each other.
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Transformace dynamické odolnosti nerezových ocelí vlivem strukturní nehomogenity
Dobrovolný, Pavel
This diploma thesis: Transformation of the dynamic resistance of stainless steels due to structural inhomogeneity deals with the effects of corrosive damage on fatigue properties of stainless steels. The theoretical part deals with general principles of creation and chemical reactions, the factors affecting their speed, as well as, fatigue properties of materials (formation of cracks, stages of high cycles fatigue, fatigue slip zone etc.) and description of the method of non destructive testing the acoustic emission. The practical part describes executed experiment which focuses on comparing the results of fatigue tests between the standards and thermal and corrosion exposed samples. The actual measurements supplement microscopic images of the fracture surfaces and the records acoustic emission during measurements of some samples.
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On the milling technology of thin-walled parts for aerospace industry
Ohnišťová, Petra ; Polzer, Aleš (referee) ; Píška, Miroslav (advisor)
This thesis is focused on the analysis and on the design of the milling technology of the components for the aerospace industry which are characterised by a high aspect ratio, reduced stiffness and all covered by a high demand on the fatigue performance. This work includes the experimental verification of the proposed technology using CNC machining center, evaluation of surface structure using optical high-resolution 3D surface measurement system ALICONA, analysis of the force loading using KISTLER device, fatigue testing and fatigue fracture analysis.
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Fatigue properties of weathering steel
Zavadilová, Petra ; Věchet, Stanislav (referee) ; Kunz, Ludvík (advisor)
This work deals with the influence of atmospheric corrosion on high-cycle fatigue properties of a weathering steel ATMOFIX B. New experimental data on fatigue strength of a steel exposed for 20 years to an atmospheric corrosion were compared to those characterizing the base material. Reduction of the fatigue lifetime of the exposed material compared with the base material was predicted on the basic of fractographic examination of fracture surfaces and the influence of surface notches on fatigue strength. The predicted results agree well with the experimental results.
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Fatigue properties of weathering steel
Zavadilová, Petra ; Věchet, Stanislav (referee) ; Kunz, Ludvík (advisor)
This work deals with the influence of atmospheric corrosion on high-cycle fatigue properties of a weathering steel ATMOFIX B. New experimental data on fatigue strength of a steel exposed for 20 years to an atmospheric corrosion were compared to those characterizing the base material. Reduction of the fatigue lifetime of the exposed material compared with the base material was predicted on the basic of fractographic examination of fracture surfaces and the influence of surface notches on fatigue strength. The predicted results agree well with the experimental results.
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