This Diploma thesis deals with a design of a powertrain of fice-cylinder gasoline radial engine with assigned main parameters (bore, stroke, etc.). The work is divided into several parts: kinematics of the radial engine, creation of 3D models, force acting on the connecting rods, balancing of the engine. The last part is focused on creating MKP models, stress analysis and determining of fatigue safety of the selected parts.

The master’s thesis deals with the fatigue life prediction under multiaxial cyclic loading. First, the fatigue process is discussed and the methods for fatigue life prediction under uniaxial and multiaxial loading are described. In the practical part, the accuracy of selected criteria is assessed based on experimental data obtained on cylindrical samples made of 1.2210 steel that were tested under synchronous symmetric axial-torsion loading. Application of criteria requires to determine the fatigue strength under pure axial and torsional loading.

This thesis examines influence of thermal shock on fatigue of pressure equipment components. The paper relates to project of IMI CCI Brno, which is a leading manufacturer of valves for the energy and process industries. Analysis concerns the impact of thermal shock concentrating on high pressure part of the steam valve. And proposal for a new valve geometry that reduces machining operations and reduce financial costs of production. First part of the thesis presents a basic review of fatigue damage components concerning mechanical loading and thermal – mechanical loading. Second part of the study creates FEM model of the valve. FEM model simulate temperature field and stress during thermal shock. Influence of thermal shock to fatigue damage was computed on basis of stress tensor obtained from FEM simulation under Chapter 18 of the standard EN 13445-3. Existing valve geometry was verified and the new geometry was proposed that simplified and reduce financial costs of production.

This master thesis focuses on subjectively percieved quality of sleep and its connections - fatigue, daytime sleepiness and insomnia in older age. Attention is brought to psychological methods of sleep measurement in comparison with objective methods (polysomnography and actigraphy). Theoretical part is based on current scientific knowledge of sleep quality and deals with psychological factors that contribute to improvement or reduction of sleep quality in older age. In context with quality of sleep focus is aimed also at presence of insomnia in older age compared to younger age and possibilities of enhancing sleep quality. Overview of subjective and objective methods of measuring sleep quality and other sleep characteristics is part of the theoretical background. Empirical part of the thesis is divided into two sections. First section compares sleep quality, fatigue, daytime sleepiness and insomnia of younger and older adults. This research is based on following questionnaire data: PSQI (Pittsburgh Sleep Quality Index), FSS (Fatigue Severity Scale), ESS (Epworth Sleepiness Scale) and ISI (Insomnia Severity Index). Second section of the research verifies the validity of psychological methods of measuring sleep quality - questionnaires PSQI, FSS, ESS, ISI and sleep diaries of older adults by...

This thesis deals with the low cycle fatigue nickel-based superalloy IN713LC with applied TBC barrier at high temperature. The theoretical part is divided into four sections. The first one focuses on description of fatigue damage. The second one provides the basic characteristics of nickel-based superalloys. The third section describes the use of the surface layers - diffusion layers and thermal barriers and the fourth section deals with the influence of these layers on fatigue properties. Experimental part is focused on the evaluation of low cycle fatigue tests and on the explanation of the mechanisms of initiation and propagation of fatigue cracks. For the experimental part, fatigue samples were prepared by vacuum precision investment casting. TBC barrier was applied by atmospheric plasma spraying and consists of two sublayers - the lower metallic bond coating type CoNiCrAlY and top ceramic coating type YSZ. Low cycle fatigue tests were conducted under strain control at controlled temperature of 900 ° C. Fractographical analysis of fracture surfaces was carried out by using light and electron microscopy. Effect of applied barrier to fatigue life was determined - the parameters of Manson-Coffin and Basquin curve. A cyclic stress-strain curve was also obtained. The curves softening / hardening and number of transit cycles were determined. The obtained parameters and values from fatigue tests were compared with available data from fatigue tests of superalloy IN713LC without the layer, as applied AlSi type diffusion layer, at high temperatures. The initiation site on the fracture surfaces was determined within the fractographic evaluation and the influence of the layer on the initiation and propagation of fatigue cracks was discussed. A helpful tool was the assessment of longitudinal sections using scanning electron microscopy.

The present diploma thesis is focused on the effect of AlCr layer on the low cycle fatigue behaviour of cast polycrystalline superalloy IN713LC at 800°C. Protective layer is made by chemical vapour deposition followed by heat treatment. Fatigue tests were conducted in strain control mode with constant total strain amplitude and strain rate. The fatigue behaviour is assessed by cyclic hardening/softening curves, cyclic stress-strain curves, Manson-Coffin curves and Basquin curves. Microstructure was observed in as-received state and also after cyclic loading by means of optical microscopy and SEM.

The main content of this master's thesis is a determination of the fatigue properties by using non-destructive testing methods – the acoustic emission technique and the X-ray diffraction. The reactor steel, that is named GOST 15Ch2NMFA, is used as a model material and is used to manufacture VVER-1000 reactor pressure vessels. The supplied material was made of two different steel melting, designated as H and S. For the basic measurement of the fatigue properties the stress-cycle asymmetry R = -1 was used. Some of the samples were used for approximate determination of the fatigue strength stress-cycle asymmetry R = 0. During the loading process the resonance frequency of the loading machine and acoustic emission signals were recorded. The changes in microstructure were estimated from the record of acoustic emissions during the whole fatigue life. The change of the microstructure was experimentally observed by X-ray diffraction analysis. The mechanism of the fatigue can be described by the observation of the microstructural processes as well as the relevant bifurcation with sufficient sensitivity. The results of the used methods indicate a decay and re-growth of mosaic blocks during the whole loading process. Therefore, it is important to find a correlation of these two non-destructive methods, or to use other non-destructive testing methods in the future.

This PhD thesis deals with the experimental study of more precise rolling contact fatigue damage detection using acoustic emission method. A series of experiments was carried out on two representatives bearing steels and the analysis of sensitivity for the presence of contact damage was performed on selected parameters of acoustic emission. The extent of damage was classified into four classes and signal parameters the most characterizing the development of damage were correlated with the extent of damage. It was also verified the influence of lubricants on acoustic emission signals. The results have an impact on the implementation of more precise rolling contact fatigue tests and evaluation of parameters of acoustic emission signal. On the basis of experiments was established methodology for more precise RCF testing method using acoustic emission on test-rig AXMAT II.

The general topic of this work is to reveal the potential relationship between tiredness cause by hypokinetic monotonous loading and breathing. The aim was to determine if there are suitable respiratory parameters that would indicate this tirednes and, if so, then verify their validity for predicting the tiredness phenomena accompanying huge range of everyday human activities. The performed experiment was attended by five volunteers who absolved measurements of electrical activity of brain, of breathing and of chest volume changes. The course of the experiment and the behaviour of probands were recorded by a camera. In the first part of each maesuremnt, a specified monotonous task (Task Tracking) was performed. The probands have had to follow the target moving with pseudocasual direction and speed by the cursor on the monitor. This task currently reflected the level of reliability and quality of the performed aktivity. In the second part of measurement, the probands had just to relax and watch a movie. Both parts were measured in two conditions - alert and tired (after 24 hours of sleep deprivation) proband. The data were compared with each other and evaluated. The measurements and the results showed that the rate of the tiredness can be fairly reliably assessed by monitoring of the volume...

Title: Electromyographic Analysis of the Different Handlebars Grips Effect on the Shoulder Blade Fixators Aims: The main objective of this thesis is to carry out a methodological study on the impact of different handlebars grips on the shoulder blades fixators. Result of the grip change is not only reduction of the upper fixators activity and the increase in the lower fixators activity but also co-contraction index increase and muscle fatigue reduction. Based on the hypothesis we assumed that the highest activity rate of the lower blades fixators and the lowest activity rate of the upper blades fixators will be during the handlebars brakes grip. The highest co- contraction index will occur during the handlebar brakes grip and the maximum muscular fatigue will occur during the grip at the top of the handlebars. The first part of the thesis is focused on the literature search and facts retrieval pertaining to the studied issue. In the second special part of the thesis we conducted a research during which the muscle activity of the upper and lower blade fixators was recorded. Three different handlebars grips were considered during the measurement using the cycle ergometer. Methods: Muscle activity was scanned and recorded using surface EMG. Maximal voluntary contraction of selected muscles based on...