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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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Pregnancy, birth and new-born care in the 16 th and 17 th centuries professional practices and reflection
Prudilová, Michaela ; Král, Pavel (advisor) ; Buriánková, Božena (referee) ; Vachková, Eva (referee)
The bachelor's thesis deals with pregnancy, birth, child-bed and new-born care in the early modern period. It attempts to reveal how women and the society of the period understood the knowledge on conception, fetus, sterility and child mortality. Using the examples of medical books from the 16th and 17th centuries, the work describes the professional practices of doctors and mid-wives and compares them with contemporary medical science. It also examines how the information from the medical books penetrated the everyday lives of the noble society.
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Psychological factors of weight loss in patients after bariatric surgery
Zajícová, Markéta ; Hrachovinová, Tamara (advisor) ; Müllerová, Dana (referee) ; Král, Pavel (referee)
Title: Psychological Factors of Weight Loss in Patients after Bariatric Surgery Author: PhDr. Markéta Zajícová Department: Department of Psychology, Charles University in Prague, Faculty of Arts Supervisor: PhDr. Tamara Hrachovinová, PhD. Abstract: Obesity with its comorbidities has enormous impacts on the life of the individual as well as the whole society. Therefore, the attention is paid to the treatment of obesity, where bariatric surgery appears to be one of the most effective. The surgical solution offers excellent results in terms of weight reduction in the short- and medium-term period, but the increased number of weigh gain cases appears in long-term perspective. The aim of this thesis is to find out whether any of the psychological factors that are included in the psychological assessment prior to the bariatric surgery, can predict the development of weight after the surgical procedure. The research is retrospective and quantitative; it focuses on monitoring variables from psychological assessment as well as weight development from the time of the surgery to 4 years after the surgery with intervals of 3, 6, 9 months and 1, 2, 3, 4 years. Attention is focused not only on the weight itself, but also on the weight change (compared to the initial weight and the comparison between consecutive...
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WE43 BIOCOMPATIBLE ALLOY AFTER SEVERE PLASTIC DEFORMATION: STRUCTURE CHARACTERIZATION
Kunčická, Lenka ; Král, Petr ; Dvořák, Jiří ; Kocich, R.
The report presents results of the analyses of biocompatible WE 43 Mg-based alloy processed by friction stir processing (FSP) at two different rotational speeds of 400 RPM, and 1200 RPM. The structures were observed by scanning electron microscopy (SEM), electron backscattered diffraction (EBSD). Observations were primarily focused on characterizations of grains and textures, supplementary testing of mechanical properties was performed via tensile tests. The results of low angle grain boundaries fractions and grain sizes showed that both the processing methods led to significant grain refinement and recrystallization, the average grain diameter within the 1200 RPM sample was less than 2 μm. Texture observations showed slight tendencies of the grains to align in the {0001}〈101̅0〉 and {0001}〈112̅0〉 preferential orientations, however, the maximum intensities were only about two times random. Supplementary tensile tests confirmed the positive effects of FSP on structures and properties of both the samples.
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