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Evaluation of sample geometry effect on creep deformation progress using acoustic emission method
Dvořák, Jiří ; Sklenička, Václav ; Král, Petr ; Kvapilová, Marie ; Svobodová, M. ; Šifner, J. ; Koula, V.
This work deals with the determination of the influence of the sample geometry on the development of failure during creep exposure. Creep tests were carried out at temperature of 600 °C and a stress of 180 MPa in the protective atmosphere of argon. P92 steel samples with a conventional smooth surface and samples with a V-groove notch were chosen for the test tests. The results of creep resistance and fracture behaviour were complemented by detailed microstructural characterization to assess damage initiation and development. Based on the measured results, the creep data was evaluated using neural networks that systematically search for and process the signal from the acoustic emission (AE). Acoustic emission serves here as an effective non-destructive method for early prediction of the beginning of a possible accident of components of power and chemical plants.
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Nonlinear analysis of reinforced concrete structures
Král, Petr ; Salajka, Vlastislav (referee) ; Hradil, Petr (advisor)
The aim is to design and evaluate nonlinear beams analysis, which will be subjected by four – point bending. Nonlinear analysis will be performed and evaluated on three beam models, the first of which will be made from plain concrete, the second of which will be made from reinforced concrete with reinforcement bars in the domain of tensile stress and the third of which will be made from reinforced concrete with reinforcement bars in domains of tensile and compressive stress. The thesis will be included formation of appropriate FE models, performance of nonlinear calculations with using nonlinear material model from a library of nonlinear material models multiPlas in the programming environment of software ANSYS and subsequent evaluation of results. Evaluation of results will consist from evaluation of nonlinear beams analysis and from evaluation of beams analysis according to ČSN EN 1992 – 1 – 1 without reinforcement bars and with reinforcement bars in these variants, next from comparison of nonlinear beams analysis with a beams analysis according to ČSN EN 1992 – 1 – 1 and finally from evaluation of the yield condition, which will be applied to the beams.
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Verification of nonlinear material models of concrete
Král, Petr ; Němec, Ivan (referee) ; Hradil, Petr (advisor)
Diploma thesis is focused on the description of the parameters of nonlinear material models of concrete, which are implemented in a computational system LS-DYNA, interacting with performance of nonlinear test calculations in system LS-DYNA on selected problems, which are formed mainly by simulations of tests of mechanical and physical properties of concrete in uniaxial compressive and tensile on cylinders with applying different boundary conditions and by simulation of bending slab, with subsequent comparison of some results of test calculations with results of the experiment. The thesis includes creation of appropriate geometric models of selected problems, meshing of these geometric models, description of parameters and application of nonlinear material models of concrete on selected problems, application of loads and boundary conditions on selected problems and performance of nonlinear calculations in a computational system LS-DYNA. Evaluation of results is made on the basis of stress-strain diagrams and load-displacement diagrams based on nonlinear calculations taking into account strain rate effects and on the basis of hysteresis curves based on nonlinear calculations in case of application of cyclic loading on selected problems. Verification of nonlinear material models of concrete is made on the basis of comparison of some results of test calculations with results obtained from the experiment.
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The Proposal of Improvement in Offer of Hotel Services
Jašová, Zuzana ; Král, Petr (referee) ; Mikulec, Luděk (advisor)
The diploma thesis was processed at the Hotel Pod Zámkem at Velké Meziříčí. It analyzes and evaluates its marketing communication and examines imperfections in this field. It contains proposals for improving the company promotion, which include new methods of the company marketing communication and their application in practice, leading to a growth of the hotel and the restaurant.
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Evaluation of energetic byproducts via selected ecotoxicity tests
Král, Petr ; Modlitbová, Pavlína (referee) ; Zlámalová Gargošová, Helena (advisor)
The topic of bachelor thesis is the study of ecotoxicity of energetic byproducts generated from the power industry. The theoretical part is focused on current problems concerning waste ecotoxicity testing namely on needs of ecotoxicity testing not only in terrestric but also in aquatic arrangement. In practical part selected energetic byproduct were evaluated via Acute toxicity test and Avoidance test on soil organism earthworm (Eisenia fetida) and Plant root growth inhibition test on letuce and onion (Lactuca sativa a Allium cepa). Luminescent bacteria test on Vibrio fischeri was also used. Obtained results served for evaluation of potential ecotoxicity of energetic byproducts discussion. It was found that test in contact arrangement is very important for complex evaluation of negative effects of matrices entering the ecosystem. Also the importance of test on luminescent bacteria Vibrio fischeri is not negligible, because provides additional information of effects on representatives of destruents as an important ecosystem function part.
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Absorption of gaseous pollutants on membrane contactors
Král, Petr ; Dohnal, Mirko (referee) ; Svěrák, Tomáš (advisor)
The diploma thesis is devoted to the separation of a pollutant (NH3) from a water solution using an experimental technology device - membrane contactor. The theoretical part is mostly focused on the recent progress in the field of membrane contactors. The theoretical part also contains theory of absorption, chemisorption and microreactions, which is needed to understand the subject properly. The experimental part focuses on the construction of the experimental device and what does experimental device consist of. The efficiency of the device in transfer of ammonia to an nitrate salt of nitric acid solution was tested. At the end, experimental data are further discussed.
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Influence of severe plastic deformation and subsequent annealing on creep behaviour of martensitic 9% Cr steel
Král, Petr ; Dvořák, Jiří ; Sklenička, Václav ; Horita, Z. ; Tokizawa, Y. ; Tang, Y. ; Kunčická, Lenka ; Kuchařová, Květa ; Kvapilová, Marie ; Svobodová, M.
The objective of the study is to evaluate the effects of severe plastic deformation (SPD) and annealing on creep behaviour of advanced tungsten modified creep-resistant 9 % Cr martensitic P92 steel. The as-received P92 steel was deformed by high-pressure torsion (HTP), high-pressure sliding (HPS) and rotary swaging (RS) at room temperature prior creep testing. These SPD methods imposed significantly different equivalent plastic strain in the range from 1 up to 20. Constant load creep tests in tension were performed in an argon atmosphere at 873 K and applied stress ranging from 50 to 200 MPa. The microstructure and phase composition of P92 steel were studied using a scanning electron microscope Tescan Lyra 3 and a transmission electron microscope Jeol 2100F. The results show that under the same creep loading conditions the HPT and HPS-processed P92 steel exhibited significantly faster minimum creep rates, creep fracture strain and the decrease in the value of the stress exponent of the creep rate in comparison with as-received P92 steel. However, it was revealed that the RS-processed specimens exhibited one order of magnitude lower minimum creep rate and lower ductility compared to commercial P92 steel. The creep curves for the HPT and HPS-processed states exhibited a pronounced minimum of strain rate. The pronounced minimum of strain rate disappeared when these states were annealed at 923K/500h before application of creep loading. The microstructure changes occurring during creep and different creep behaviour between as-received and deformed states are discussed.
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Using the identification of parameters of nonlinear material models for analysis of concrete structures
Král, Petr ; Králik, Juraj (referee) ; Maňas,, Pavel (referee) ; Hradil, Petr (advisor)
The presented thesis is focused on numerical modeling of concrete behavior (response) using nonlinear material models (constitutive relations) and on identification of input parameter values of these material models. Nowadays, there are a number of mathematically formulated constitutive relations intended not only to simulate the response of ductile or brittle materials, but also quasi-brittle materials. The constitutive relations for quasi-brittle materials are based on various theories (plasticity theory, the concept of damage mechanics, nonlinear fracture mechanics) and their complexity depends on the chosen type of solver. A general problem in the use of these constitutive relations is the need to define the values of their input parameters which these models usually include a very large number, and which often lack physical meaning, with their meaning being purely mathematical or experimental. This problem escalates with the increasing complexity of material models, which occurs in the transition from the formulation for the classic finite element method (FEM) to the formulation for the explicit FEM, and greatly complicates their practical application. The aim of this thesis is to present an approach how to deal with this problem for selected nonlinear constitutive relations. For this purpose, the thesis is divided into three main thematic parts. The first main part of the thesis is focused on the identification of input parameter values of the Continuous Surface Cap model. The purpose of this part is to first verify the effectivity and accuracy of the selected identification procedures. The following is the identification of model parameter values based on experimental data in order to adjust the derived calibration curves. In this part, the identification of input parameter values is demonstrated on both versions of the model. Data from the direct tensile test, compact tension test and four-point bending test of concrete are used. The second main part of th
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Elements of Addiction: Factors of Success in Treatment for Drug Addict from Bio-Psychosocial-Spiritual Point of View
Král, Petr ; Sivek, Vojtěch (advisor) ; Libra, Jiří (referee)
The whole work tries to elaborate the theme of addiction on addictive substances in focus on bio- psychosocial-spiritual part of the whole problem. Human personality has the deep based predisposition to be addictive and it has a complete potential to become addictive in all ways. The occasions of this addiction are able to be found in all domains of human being, beginning with physiognomy and ending with spirituality. The reasons why the subject becomes addictive or eventually only tries the addictive substances are able to be found in looking for transcendent experience, sense of existence, in escaping from problems, pain or killing the bore or solitude. If the human becomes addictive he starts an inescapable way leading straight to total destruction of personality in all its qualities. Spiritual part of personality, the self-awareness, the unity and the normal values are damaged by the addiction and the human is moving himself to his own animalism oriented to acquiring substances. The way back devoid of sleeks of nonsensicality is not easy but possibly to be found. The most of addictives go through the resocialization centers on their ways and so these centers could play a key role in changing the life and abstinence. This work tries to describe these factors, which the whole cure should imply. And...
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