The diploma thesis deals with crab frame of bridge magnet crane with lifting capacity 15t used in steel mill for handling billets. Thesis contains strength analysis and fatigue strength check of crab frame based on ČSN EN 13001. Strength analyses are made by using beam and shell models of finite element method. The diploma thesis was carried out in cooperation with Královopolská a.s. company.

This thesis describes design of new circumferential blade attachment on last grade of steam turbine and following stress-strain analysis by FEM with static and cyclic loading. It was created two new design of geometry, which were created based on existing and operating constructional solution of oblique double T blade attachment. It was made stress-strain FEM analysis on original design of blades. Its results served to realize change of construction. Their target was increase load capacity and service life of new types of blade attachment.

Hlavním cílem této práce bylo vysvětlit únavové chování ocelí ODS Eurofer, 14Cr ODS feritické oceli vyráběné v CEA (Commissariat a l’énergie atomique, Saclay, France) a 14Cr ODS feritické oceli vyráběné v EPFL (École Polytechnique Fédérale de Laussane, Switzerland). Pokud to bylo možné byly získané výsledky porovnány s ocelí Eurofer 97. Tato práce je součástí široké spolupráce, která je zaměřena na vývoj konstrukčních materiálů pro fuzní reaktory. V průběhu práce byly provedeny následující experimenty: • Standardní únavové zkoušky za pokojové teploty, při 650 a při 750 , byly získány křivky cyklického zpevnění/změkčení, cyklické deformační křivky, Coffinovy–Mansonovy a Wöhlerovi křivky. Hysterezní smyčky byly detailně analyzovány. • Pozorování mikrostruktury výchozího stavu pomocí TEM a porovnání s mikrostrukturou po cyklickém zatížení. • Pozorování povrchového reliéfu, který vznik díky lokalizaci cyklické plastické deformace - byla odhalena místa iniciace únavových trhlin a byl analyzován mechanismus jejich vzniku. • Měření kinetiky únavových trhlin. Oxidická disperse značně zpevňuje materiály, redukuje cyklické změkčení a stabilizuje mikrostrukturu v celém rozsahu teplot. Byly nalezeny velké rozdíly v životnosti jednotlivých ocelí. Ty byly vysvětleny pomocí rozdílných mechanismů iniciace trhlin a jejich různou rychlostí.

This dissertation examines life-time management of process and energetic devices in industrial practice, mainly in the area of steam power plants. Furthermore, it focuses on frequent damage mechanisms occurring in this area. It summarizes basics of damaging mechanisms occurring in the process industry area, their monitoring, evaluation and prediction. In the area of steam power plants, the main emphasize was placed on cumulative damage mechanisms. Within the dissertation, mechanisms of creep, fatigue, and their combinations were assessed. Major European standards were examined in order to discuss the amount of contained conservatism and their usability. Subsequently, attention was paid to the methods applicable for creep and fatigue combination evaluation. In the next step life-time monitoring and evaluation standard was discussed. The diagnostic software was created which includes creep, fatigue and creep-fatigue combination evaluation according to valid standards. For online life-time evaluation was proposed refined analytical solution for stress and strain calculation. To further extend the life-time management, the dissertation describes oxide scale damaging together with its evaluation and implementation into diagnostic software. The proposed software is extended by the material module which on the basis of defined materials allows easy and effective usage of material characteristics. For the purpose of refining life-time prediction accuracy, experimental device was schematically described. In addition, the device should be also able to verify used equations. Furthermore, the dissertation includes solution to industrially oriented cases. Firstly, a steam generator with damaged pipes was analyzed, afterwards damaged transferring pipeline. Further analyses deal with U-tube heat exchanger and its damaging. The causes of damage were discovered and corrective measures were proposed. The dissertation concludes with the summarization of potential activities for subsequent research in examined area.

Diplomová práce popisuje metodiku výpočtů částí náchylných k rozvoji mnoho-ohniskového únavového poškození (WFD). Nejdříve se práce zabývá rozborem předpisů letové způsobilosti souvisejících s WFD pro letadla certifikovaných podle FAR 23 v kategorii commuter. Následuje popis metodiky únavového výpočtu a predikce šíření trhliny. Dále jsou popsány řešení pro výpočet faktoru intenzity napětí pro základné konfigurace trhliny, tam kde to bylo možné v uzavřeném tvaru, jinak ve formě tabulky. Hlavní částí práce je návrh algoritmu AIMA schopného provést kompletní analýzu části náchylné k rozvoji únavového poškození na více místech (MSD). Model se validoval únavovou zkouškou vzorku přeplátovaného spoje dolního panelu křídla. Následně byla analyzována reálná konstrukce spoje dolních panelů křídla letounu L 410 NG.

This Master Thesis compares three various concrete materials for stiffening orthotropic bridge deck plate and investigates stress reducing factors in selected weld joints. The thesis investigates the standard load situation and also overloaded situation. A parameter study with different material inputs has been done to see how it affects stress in weld joints.

This thesis describes selection and shows calibration of material model, capable of describing cyclic softening of material. Stress-strain FEM analysis of circumferential blade attachment for last section of rotor blades of steam turbine is performed, expected lifetime of existing attachment is evaluated. Multi-parameter optimization of new-shape attachment was done, resulting in dimensions for new-shape attachment with longer lifetime. Improvements in strain amount in comparison with existing attachment were evaluated and possible RPM increase of turbine with new attachment type was calculated.

1) INTRODUCTION: Obesity is a global problem and its the prevalence is constantly rising. Overweight and obesity are key risk factors for many diseases. Obese patients are a greater economic burden for the state, they often rely on the help of others. The goal of obesity treatment is to reduce weight and then keep it within the recommended range. In an obese patient, it is not always just about the actual weight loss, but also about treating the associated diseases caused by obesity. Bariatric surgery allows patients to lose weight in a relatively short period of time and has a very positive effect on associated diseases. 2) OBJECTIVE: The aim of this diploma thesis was to evaluate the physical and mental condition before and after gastric bypass and to determine whether this surgery has a positive or negative effect on the physical and mental condition of the patient. The objective was further divided into sub-goals and hypotheses. 3) METHODOLOGY: The research was carried out using a quantitative method. This is an observational study, in which the mental and physical condition and advancement of patients who were about to undergo bariatric surgery - gastric bypass - were monitored for 6 months. Mental status was monitored using four standardized questionnaires: MAF, HADS, iADL, SF-36 in four time...

INTRODUCTION TO THE ISSUE: Obesity together with possible occurrence of many difficulties carries with it negative effect on physical and mental health. Many patients with severe obesity (class 3) cannot do physical activities or usual daily activities. These patients suffer from feelings of inferiority, decreased self-esteem and other mental issues. It could be classified as a vicious cycle for patients, but the bariatric surgery offers a way out. A gastric bypass is one of the bariatric procedures which is very helpful to reduce the weight of the patients who belongs into class 3 obesity. OBJECTIVES, METHODOLOGY: The main goal of this study was to find out if applying the gastric bypass to patients has positive or negative effect for their obesity level, quality of life, physical and mental state. The research sample was consisted of patients who were about to undergo gastric bypass. The patient's weight, BMI and body fat ratio were monitored to obtain data related to the assessment of the severity of obesity. The quality of life was evaluated using the SF-36 questionnaire (Short form 36). The standardized MAF (Multidimensional Assessment of Fatigue Scale) was used to review of patient's fatigue. The mental state of patients was subjectively assessed using the standardized HADS scale (Hospital...

This Ph.D. thesis was written under the supervision of Assoc. prof. Pavel Hutař, Ph.D., and Assoc. prof. Luboš Náhlík, Ph.D. The thesis is focused on the effect of plasticity induced crack closure, its characteristic and ways of numerical modelling. Premature fatigue crack closure has a significant effect on the fatigue crack propagation rate and therefore on the residual lifetime of a structure. A three-dimensional numerical model allows a detailed look at the stress and strain distribution along the crack front, and particularly it allows a local description of parameters along the crack front which governs the fatigue crack propagation rate. In the first part of the thesis, the study is focused on the influence of a singular stress field at the vicinity of the free surface on the crack front curvature without crack closure being involved. In the second part, a numerical model in 2D of plasticity induced crack closure was created and verified by experimental results. In the final part, a 3D numerical model is used to describe the influence of the crack closure on its fatigue propagation rate and explains typical crack front curvature. The suggested technique allows quantitative accuracy improvement of numerical simulation of the fatigue crack propagation and therefore, more reliable estimation of the residual lifetime of the cracked structure.