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Computer analyse of LBIC pictures
Štencel, Jakub ; Křivík, Petr (referee) ; Vaněk, Jiří (advisor)
This thesis is concerned with image picture analysis, especially with images obtained by diagnostic LBIC method. The individual defects occuring on solar cells are described in theoretical part, including methods which serve for making referential image. Furthermore, the creation of difference image is analysed, from whom the interferences will be evaluated. The aim of practical part is to focus on generation of algorithms which investigate the defects, and the description of application for program control is described in conclusion.
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Design of a test rig for stress visualisation using photoelasticimetry
Doležel, Miroslav ; Rebenda, David (referee) ; Michalec, Michal (advisor)
The purpose of this work is to construct a specific loading device for the observation of moving samples in the existing polariscope. The experimental method of photoelasticity is often used to observe stationary samples, but the observation of moving samples is less common. However, the time-varying development of the stress profile is very important for understanding of the stress cycles in the machine components. The theoretical part contains a basic information about the method of photoelasticity, its advantages and limitations and the possibility of its use. Then the dynamically stressed machine elements are mentioned, from which the gear is selected as a preferable element for observation in the polariscope. Furthermore, attention is focused on materials and techniques of sample production. The determination of the required load of the gear sample is based on these findings. The most suitable design of the loading device capable of inducing specified stress in the samples is proposed and the critical nodes of the structure are supported by the strength calculations. This design offers variability for clamping different sample sizes and can thus be used to investigate stress in other gear configurations as well.
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Static Analysis of Structural Elements of Glass
Hořký, Radek ; Gratza, Roman (referee) ; Kytýr, Jiří (advisor)
They analyzed the various factors affecting the design or evaluation of structural glass. Within evaluation of structural glass element is checked selected concepts of linear elastic fracture mechanics. For modeling is used programme system ANSYS based finite element method. The results are compared with the analytical solution.
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Design of a test rig for stress visualisation using photoelasticimetry
Doležel, Miroslav ; Rebenda, David (referee) ; Michalec, Michal (advisor)
The purpose of this work is to construct a specific loading device for the observation of moving samples in the existing polariscope. The experimental method of photoelasticity is often used to observe stationary samples, but the observation of moving samples is less common. However, the time-varying development of the stress profile is very important for understanding of the stress cycles in the machine components. The theoretical part contains a basic information about the method of photoelasticity, its advantages and limitations and the possibility of its use. Then the dynamically stressed machine elements are mentioned, from which the gear is selected as a preferable element for observation in the polariscope. Furthermore, attention is focused on materials and techniques of sample production. The determination of the required load of the gear sample is based on these findings. The most suitable design of the loading device capable of inducing specified stress in the samples is proposed and the critical nodes of the structure are supported by the strength calculations. This design offers variability for clamping different sample sizes and can thus be used to investigate stress in other gear configurations as well.
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Static Analysis of Structural Elements of Glass
Hořký, Radek ; Gratza, Roman (referee) ; Kytýr, Jiří (advisor)
They analyzed the various factors affecting the design or evaluation of structural glass. Within evaluation of structural glass element is checked selected concepts of linear elastic fracture mechanics. For modeling is used programme system ANSYS based finite element method. The results are compared with the analytical solution.
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Computer analyse of LBIC pictures
Štencel, Jakub ; Křivík, Petr (referee) ; Vaněk, Jiří (advisor)
This thesis is concerned with image picture analysis, especially with images obtained by diagnostic LBIC method. The individual defects occuring on solar cells are described in theoretical part, including methods which serve for making referential image. Furthermore, the creation of difference image is analysed, from whom the interferences will be evaluated. The aim of practical part is to focus on generation of algorithms which investigate the defects, and the description of application for program control is described in conclusion.
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Analysis of cyclic plasticity of fatigued nickel based superalloys at elevated temperatures
Petrenec, Martin ; Tobiáš, Jiří ; Polák, Jaroslav ; Šmíd, Miroslav ; Chlupová, Alice ; Petráš, Roman
Cyclic strain controlled multiple step tests have been performed on cylindrical specimens of cast Inconel 738LC superalloy at 23 and 800 °C and Inconel 792-5A superalloy at 800 °C in laboratory atmosphere. The effect of temperature on the cyclic stress-strain response characterized by internal and effective cyclic stress components and on the dislocation arrangement has been studied. The evolution of the effective and internal stress components and effective elastic moduli were derived from the hysteresis loops analyzed according to the statistical theory of the hysteresis loop. Cyclic hardening/softening curves and shortened cyclic stress-strain curves were obtained at all temperatures in both superalloys. The shortened cyclic stress-strain curves (CSSCs) can be fitted by power law at all temperatures and for both materials. They are shifted to lower stresses with increasing temperature. The CSSC of Inconel 792-5A is shifted to higher stress amplitude in comparison with that of Inconel 738LC due to different number and type of precipitates. Observation of dislocation structures by TEM revealed cyclic strain localization into persistent slip bands. Cyclic stress-strain response is compared at all temperatures in both superalloys and discussed in relation to the changes of internal and effective stress components and microstructural parameters of the material. Higher stress response of the Inconel 792-5A than of the Inconel 738LC superalloy at 800°C is due to higher effective stresses of respective γ´ phases.
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