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Stability analysis of swinging props turbines
Bukovský, Petr ; Navrátil, Petr (referee) ; Skalka, Petr (advisor)
Master thesis deals with a computing simulation of two props turbines lines. The thesis output is gaining maximum possible load, at which a commencement of deformation stability critical state for various geometrical imperfections has not arisen yet. The calculation has been done by FEM in two different ways: linear solution (using a calculation conversion into eigenbuckling) and nonlinear solution (using a FEM deformation option). Result analysis compares both methods outcomes. Safety factor for the props operation has been proposed taking into consideration known influences on operating state.
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Methods of fixation of the upper limb fractures
Litera, Jan ; Marcián, Petr (referee) ; Florian, Zdeněk (advisor)
The presented bachelor thesis is focused on current methods of a fixation of upper limb fractures. Part of the thesis is a literature review and a description of the upper limb anatomy. This is necessary to solve the problems associated with upper limb fractures. The history of the treatment of upper limb fractures enables to gain an insight and a benefit of the current methods of the fixation of the upper limb. Based on the acquired knowledge, there is created a simple computational model of a humeral fracture fixation using a LCP and a classical plate. The computational model for the specific load models was solved in the Ansys Workbench 18.2 computing system. The biomechanical analysis based on the results presentation of the solution of the described simple model showed differences between the application of the LCP and the classical plate.
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Analysis of residual stresses in arterial wall
Novák, Kamil ; Fuis, Vladimír (referee) ; Burša, Jiří (advisor)
This thesis deals with computational modeling of the influence of residual stresses in idealized geometry of blood vessels and subsequent application of acquired knowledge to abdominal aortic aneurysm. In the terms of quality of the computational model, we reduced the uncertainties that are included in the computational model without considering the influence of residual stresses. The basic assumption of homogenization significant peaks of the stress between inner and outer vessel wall was met for each level of the computational model Methods that have been used are: deformation method (opening angle method), inverse mechanics of large deformations, fictitious temperature – for linear elastic material and hyperelastic material defined by the constitutive model. Numerical verification was carried out using program ANSYS.
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Virtual Prototypes of Drivelines
Janoušek, Michal ; Dundálek, Radim (referee) ; Slimařík,, Dušan (referee) ; Píštěk, Václav (advisor)
The thesis deals with computational modelling of heavy duty off-road vehicle driveline components. The thesis is divided to two main parts. The first part deals about modal analysis of selected driveline components. MBS computational study was performed based on modal analysis results. The second part of thesis deals with experimental verification of computational model. Pass-by noise and vibration measurement was performed. Measured signals were processed in frequency domain to find noise and vibration sources.
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Deformation and stress analysis of the parts of the total replacement of the trapeziometacarpal joint
Svojanovský, Tomáš ; Marcián, Petr (referee) ; Fuis, Vladimír (advisor)
The presented diploma thesis builds on author’s bachelor’s thesis of the similar name which was focused, in particular, on rhizarthrosis. Because of this joint disease, implantations of the total joint replacement are performed. The bachelor’s thesis also served as a familiarization with the finite element method and contact analyses issues, giving a theoretical framework for this diploma thesis. As opposed to that, the diploma thesis aims entirely at deformation and stress analysis of the total replacement. The main objective is to carry out analyses of different variants of geometric models. In addition, there is a tendency to analyze contact pressures of advanced model concerning all the total replacement, bone tissues, ligaments and tendons guaranteeing the static equilibrium of components. The bachelor’s thesis has been developed in ANSYS Workbench, whereas the diploma thesis in ANSYS APDL. Work in APDL allows user to control better over the entire computational process, however, requires more skills and theoretic knowledge. Contact analyses bring a lot of problems associated with convergence of procedures and accuracy of results. Therefore, explanations of important terms and set of recommendations are included for the purpose of easier solving of the contact problems.
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Evaluation of elastic parameters for models of isolated cells
Krbálek, Jaroslav ; Fuis, Vladimír (referee) ; Burša, Jiří (advisor)
This diploma thesis focuses on computational modeling of the cell mechanical tests. The goal of this thesis is to build a cell model and to simulate compression test on this model. If necessary, the model should be adjusted so the model reflects real cell behavior. It was created the cell model reflecting cytoplasm, nucleus, membrane and cell cytoskeleton. Cytoskeleton was modeled as tensegrity structure. After this, the pressure test was simulated on this model. The behavior of the cell model and real cell was compared using the stress force. The stress force - cell deformation curve was markedly different for the cell model and the real cell. For this reason, the cytoplasm material model was adjusted. The difference between the curves was acceptable after this modification. It was found during computations that the cytoskeleton model influence on the cell load is minimal. These results does not reflects real cell behavior, which means that the model is considered inadequate for performing stress load simulation.
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Literature search of possibilities of computational modelling of brain aneurysms
Lipenský, Zdeněk ; Polzer, Stanislav (referee) ; Burša, Jiří (advisor)
This bachelor thesis is focused on gathering general information about a cerebrovascular disorder called Cerebral Aneurysm (or also Brain Aneurysm) which is a medical condition consisting in an abnormal bulging outward of one of the arteries in the brain. The initial attention is given to the human cardiovascular system, a description of which is fatal for understanding the problem of brain aneurysm. The next attention is focused on the solution of eliminating the tension within the aneurysm by using knowledge gained in lectures "Flexibility and Strength II" during the sixth semester. The last chapter shows a summary of three works dealing with computational modeling of cerebral aneurysm.
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Computational modeling of the interaction of flowing blood with the artery tube with the atheroma
Freiwald, Michal ; Jagoš, Jiří (referee) ; Švancara, Pavel (advisor)
Předložená diplomová práce se zabývá interakcí mezi proudící krví a krční tepnou, obsahující aterosklerotický plat, za pomoci konečnoprvkové fluid-structure interaction analýzy. První část práce obsahuje souhrn teoretických poznatků, sestávající z kardiovaskulárního systému, cév, souvisejících konstitutivních modelů, reologie krve a úvodu do teorie proudění. Dále je v práci obsažen stručný souhrn současného poznání výpočtového modelování v této oblasti, s důrazem na strukturní a fluid-structure interaction analýzy v oblasti krční tepny, a na použité konstitutivní modely. Experimentální část se soustředí na tvorbu zjednodušeného modelu krční tepny, obsahující aterosklerotický plat, a na tvorbu odpovídajícího modelu krve. Oba modely poté společně vstupují do fluid-structure interaction analýzy, která si klade za cíl pochopit důsledky pulzujícího toku krve na stěnu tepny a na růst aterosklerotického plátu; primárními zkoumanými veličinami jsou první hlavní napětí na stěně tepny, celková deformace stěny tepny, časově zprůměrovaná hodnota smykového napětí na stěně tepny a oscilační smykový index. Všechny výsledky jsou porovnány napříč několika typy analýz, tak aby bylo možné zhodnotit rozdíly a důsledky zvoleného přístupu. Součástí práce je také zjednodušená parametrická studie, která porovnává vliv rostoucího procenta stenózy na vyhodnocované veličiny. V poslední částí práce jsou zhodnoceny výsledky, její limitace a další možnosti výzkumu v této oblasti.
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Flow through the artifitial heart valve
Šedivý, Dominik ; Pochylý, František (referee) ; Fialová, Simona (advisor)
The presented thesis solves a flow through the artificial heart valves. The thesis concerns with a historic development of mechanical heart valves and their basic parameters. It also includes a short research about Dynamic mesh module, which is contained within ANSYS Fluent. An experiment with a real mechanical heart valve was done within the diploma thesis and obtained data were compared with physiological ones. One part of this work was a design of 3D model of real heart valve replacement. The model was used for fluid dynamic computations using the Dynamic mesh of ANSYS Fluent software. In the end are the results of experimental part and numerical solutions used for few suggestions that could improve the function of the artificial heart valve.
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Computational modelling of heart contraction
Vaverka, Jiří ; Polzer, Stanislav (referee) ; Burša, Jiří (advisor)
This thesis aims to determine the impact of slowed myocardial conduction velocity and depressed myocyte contractility on the duration of isovolumic contraction time (ICT) of the left ventricle by carrying out simulations using finite element method. A 3D finite element model enabling to simulate both physiological and pathological states of myocardium was created. The model is based on simplified ellipsoidal geometry and accounts for anisotropic behavior of myocardium, its asynchronous contraction and variations in the arrangement of muscle fibers. Slowing of conduction velocity to a half of its physiological value resulted in prolongation of ICT by 27 %; slowing of shortening velocity of myocytes by the same percentage prolonged ICT by 73 %. It is therefore concluded that ICT can be much more prolonged due to depressed contractility than due to conduction slowing. The presented results give an idea of the extent to which ICT can be prolonged due to depressed contractility and conduction slowing and therefore can be useful in identifying the causes of decreased myocardial performance in heart disease.
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