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Plasticity after focal brain ischemia
Hanáková, Helena ; Mareš, Pavel (advisor) ; Zounková, Irena (referee)
The thesis is focused on brain ischemic injury with an accent on subsequent spontaneous and rehabilitation-induced plastic changes related to motor recovery. General part of thesis describes cortical anatomy and pathophysiology of brain ischaemia including classification of ischemia, ischemic cascade and reperfusion injury. There is also a chapter about spontaneous plasticity and recovery. The main part gives a survey of rat models of focal cortical ischemia, of functional assessment and rehabilitation. Results of rehabilitation-induced cortical plasticity are also presented.
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Optimalizace parametrů úlohy s rázovým zatížením v programu LS-DYNA
ŠTANGL, Jiří
Master's thesis focuses on numerical modeling of automotive tasks. The text is divided into two main parts. A fuel supply module is the main topic of all numeric analyses of this thesis and it is introduced in the first part. Basics of theoretical continuum mechanics and finite elements method are also explained in the first part. The second part is split into two main topics of the fuel supply module - material damping and contact numerical modeling. Practical reasons for parameter optimization are explained along with particular optimization results and underlying theoretical background.
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Nonlinear analysis of reinforced concrete foot failure
Dubina, Radek ; Václav,, Veselý (referee) ; Eliáš, Jan (advisor)
Reinforced concrete monolithic feet are one kind of shallow foundation used mainly under column systems. These systems transfer the load from upper floors through columns to the feet and through them to the foundation soil. Interaction between the foot and the foundation soil plays an important role due to the system sensitivity to the uneven settlement. Feet has to resist shear induced by vertical force and bending moment caused by stress in footing bottom. The work is devoted to design of the foot according to European standard Eurocode 2. It is then focused on numerical simulation of foot failure and calculation of the corresponding maximal vertical force in the column using a 3D model with nonlinear material models of subsoil, reinforcement and concrete. The calculations are done in software ATENA 3D for different variants of subsoil, reinforcement and foot shape. Results according to European standard and nonlinear analysis are compared.
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Organic architecture and contemporary residential living
Čábelková Nahorniaková, Marcela ; Kyselka, Mojmír (referee) ; Budkeová, Branislava (referee) ; Glosová, Dagmar (referee) ; Menšíková, Naděžda (advisor)
Organic architecture is often used term especially in connection with the daring and experimental form. The exact definition or division is still missing. The founder of modern organic architecture is to be generally considered as Frank Loyd Wright. He was the man who created organic architecture and also made first definition in the early twentieth century, when formulating new architectural styles. Dissertation deals with insufficiently described problem of organic architecture. The main focus is on contemporary production of residential organic architecture in Central Europe. Especially on the particular realizations in Hungary, Czech Republic, Slovak Republic, Austria, Germany and Poland. Beside detail description of European realizations, the dissertation deals also with foundations of organic architecture in U.S.A. and important realizations here. Modern organic architecture primarily originated in the United States of America. The work presents most important contemporary realizations and architects creating resident living organic architecture in other countries around the world in order to complete the overview. The objective of dissertation was describing newest trends in designing buildings for living. Find position of organic architecture and give reasons for it´s increasing popularity, spread and necessity for new development in architecture according to the new trends. Organic architecture is an alternative way of contemporary residential living. It´s popularity is growing in last years in response to the development of modern technologies and materials, the need to protect our natural resources and also to the increasing negatives of globalization and to denial of local traditions and regional specificities. Aspects of organic forms were divided into three main groups according to their main characteristics: form, harmony and sustainable development. Another objective was find location of contemporary organic residential architecture in Czech Republic and abroad. It is rather spread all over the world than concentrated on certain places. Therefore I selected countries that are richer than the others on the occurrence of organic buildings. The objective was also to address architects, specialists, public and especially university teachers of architecture and students themselves. Communication with them was mainly connected with grant project in 2010. The theme of grant project was contemporary organic architecture in residential living. There were lectures about contemporary organic architecture and exhibition on the theme: Contemporary living organic architecture. The publication of the catalog was published under the title: Contemporary organic houses - Europe. I had the opportunity to visit a number of organic family houses abroad. Specifically houses in Slovakia, Hungary and Germany. Results of survey, which was realized by questions to owners and authors of chosen buildings, are included in dissertation. The mail results of dissertation are - make a detail review of organic architecture in residential living - define trends in contemporary organic architecture and residential living - obtain and process answers from owners and authors of chosen buildings within survey - analysis of organic house ( houses) in city planning and landscape - publication of catalogue focused on organic contemporary European houses - article about contemporary organic architecture and residential living will be published in 2012 on archiweb page
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Parameter Identification for Elastic-plastic Material Models from Experimental Data
Jeník, Ivan ; Šebek, František (referee) ; Kubík, Petr (advisor)
This master's thesis deals with the identification of the material flow curve from record of tensile test of smooth cylindrical specimen. First, necessary theory background is presented. Basic terms of incremental theory of plasticity, tensile test procedure and processing its outputs are described. Furthermore, possibilities of mathematical expression of the elastic-plastic material constitutive law, thus mathematical expression of the material flow curve itself. Mechanism of ductile damage of material is explained briefly as well. Overview of recent methods of the flow curve identification is given, focused on cases, when the stress distribution in a specimen is not uniaxial. That is either kind of analytic correction of basic formulas derived for uniaxial stress state, or application of mathematical optimization techniques combined with numerical simulation of the tensile test. Also unusual method of neural network is mentioned. For 8 given materials, the flow curve identification was performed using different methods. Namely by analytic correction, optimization, sequential identification and neural network. Algorithms of the last two methods were modified. Based on assessment of obtained results, application field and adjusting the parameters of single algorithms was recommended. It showed up, that an effective way to the accurate and credible results is the combination of different methods during flow curve identification procedure.
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Computational analysis of residual stresses in autofrettaged high pressure rails
Blaha, Jakub ; Petruška, Jindřich (referee) ; Vrbka, Jan (advisor)
The master‘s thesis is aimed on numerical simulation of autofrettage of high pressure fuel vessel – rail in Common Rail system. First there is described Chaboche model, which is later used for simulation of autofrettage. There are described different approaches which can be used to obtain sufficient material model. Then there is observed influence of these different approaches on stress state of rail within the process of autofrettage. Suitability of Chaboche model for autofrettage and re-autofrettage simulations is assessed by comparing with more complex Jiang model. In the end there is a study of influence of autofrettage pressure on different properties, especially on residual stresses.
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Computational analysis of cross roll straightening of rods
Štourač, Vít ; Šebek, František (referee) ; Petruška, Jindřich (advisor)
Today is on products from the perspective of quality placed an increasing emphasis. This work is focused to the analyze of cross roll straghtening of long semifinished products with a circular cross-section. This process increased quality of semifinished products from the perspective of their curvature, because they do not reach the required limit values. Curvature of the semifinished product is due to residual stress, which is during straghtening using plastic deformation of the material redistributed and the semifinished product is leveled. This work analyzes the effect of rotation of straightening rolls on the distributiom of contact pressure between the straightening semifinished product and the roll of straightener. Author then analyzes effect of input parameters of program to straightening at the final curvature of the semifinished product. With the experience gained, then try to adjust some input parameters.
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Computational analysis of leveling of square cross section rods
Šebek, František ; Návrat, Tomáš (referee) ; Petruška, Jindřich (advisor)
Current requirements in mechanical engineering require more accurate operations and more efficient technologies. The aim of this thesis is the analysis of the leveling of square rods. The main problem is the setting of the leveling machine for the specified material and geometric data so that the initially curved material, which passes through alternatively positioned offset rollers, is leveled as much as possible. The main factor in the leveling process is the plastification of the material used for the redistribution of the residual stress. Based on existing theo-retical knowledge in this field, programs are set up to simulate the passing of the rod through the leveling machine. Further, modifications leading to the improvement of the whole process are presented. Finally, there is a verification of the results which is made independently of the submitted solution and processed by the finite element method.
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Research plasticity of foundry sands
Macků, Martin ; Křístek, Jiří (referee) ; Rusín, Karel (advisor)
The subject of this thesis was to develop a comprehensive methodology for evaluating the plasticity of molding sand. This study was focused on four types of mixtures that are used in the foundry industry. For the evaluation of plasticity was important to provide an indicator of the deformation ability, calculation of deformation and logarithmic transformation for compression. Plasticity methodology was applied in this work only on the pressure effect. Studies of this issue can have a great influence on the production of correct forms due to the ability to withstand tension without breaking form.
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Stress - strain analysis and creep assessment of the thick-walled tubular structures.
Zouhar, Michal ; Petruška, Jindřich (referee) ; Hlavoň, Pavel (advisor)
This thesis deals with the stress-strain analysis of thick-walled pipe parts. The dimension series (characterized by the D/d ratio) of three components are solved, then a direct tube, a torus with constant wall thickness (arcus) and a torus with variable wall thickness (bend). At first, the internal pressure amount, when a fully plastic state for these components is created, is solved. The amount of the limit pressure is determined analytically, numerically and by appropriate normative relations. The results and stress diagrams of individual solutions are mutually compared. Furthermore, these components are solved in the creep and are exposed to the maximum allowable normative internal pressure for 200,000 hours according to the standard – the operating time of components. The place of the maximum equivalent creep strain and the place of the maximum equivalent stress is examined. In these places the principal stresses are depicted depending on the D/d ratio. The results and stress diagrams of individual dimension series are mutually compared. From the available literary sources the condition of the limit state reach is chosen, according to which the evaluation of the limit state reach for individual components is carried out.
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