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Stress and strain analysis of different total knee endoprostheses on tibia bone tissue performance
Boháč, Petr ; Borák, Libor (referee) ; Marcián, Petr (advisor)
This diploma thesis deals with the stress-strain analysis of the influence of various total knee endoprosthesis on the periprosthetic bone tissue of the tibia. The first part of the thesis describes the problem situation and the research study related to the issue. The second part of the thesis describes the basic knowledge suitable for understanding the issues addressed. The third part of the thesis describes in detail the process of creating computational models, which should make the used methodology reproducible for possible further studies. The next part of the work analyses and presents the results of computational modelling using the finite element method. Based on the Frost hypothesis, the effects of various total knee endoprosthesis on the periprosthetic tibial bone tissue at a specified maximum load appearing in the walking cycle are evaluated and compared. At the end of the thesis, the possible consequences of this analysis are mentioned.
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Use of Retomo software for computational modeling in biomechanics
Filková, Alena ; Lisický, Ondřej (referee) ; Marcián, Petr (advisor)
This bachelor thesis deals with the issue of musculoskeletal biomechanics. More precisely, of creating a geometry model based on CT data using the RETOMO program and then a computational model. The introductory part is devoted to a brief explanation of the concepts of computed tomography and finite element methods. The following chapter provides a search of programs used to create models of geometry from CT data in biomechanics. Furthermore, the work deals with the description of selected functionalities and user environment of the RETOMO program, with the greatest emphasis on the creation of a geometry model from CT data. During the implementation of the bachelor's thesis, two models of geometry were created in the analysed program, using different segmentation functions, which were then compared with each other and then compared with a model of geometry created in another program. The GOM Inspect program was used to compare the geometry deviations of individual models. Finally, computational models were created using the CATIA program and then deformation and stress analysis was performed using the ANSYS program. The results of individual solutions were analysed, compared and evaluated.
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Development and application of computational model of ballistic resistant composite laminate
Urbášek, Jan ; Kubík, Petr (referee) ; Petruška, Jindřich (advisor)
This master thesis is aimed at computational modeling of ballistic resistant layered laminate. The introductory sections of the thesis are aimed at understanding the individual topics that are closely related to the interaction of the projectile and target and computational modeling of this process. The main goal of this thesis was to create a computational model that is able to reflect the behavior of aramid fabric during the interaction with the projectile. During the development of the computational model were used more methods of modeling and also more material models were used. For the purposes of the development of the computational model were used the available data of the companies SVS FEM s.r.o. and VVÚ s.p. The outcome of the diploma thesis is a computational model of aramid fabric which is designed for ballistic protection simulations. This model is validated on the basis of available experiments. The validated computational model is then applied to the simulation of ballistic protection.
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Computational Analysis Of Dynamic Behaviour Of Journal Bearings
Rak, Vladimír ; Kamenický, Ján (referee) ; Pochylý, František (referee) ; Zapoměl, Jaroslav (referee) ; Malenovský, Eduard (advisor)
This work deals with computational modelling of static and dynamic analyses of journal bearings, with analyses of stability of oil-film motion and analyses of response of the rotor assemblies. At our workplace a new theoretical approach to the modelling of the static and dynamic behaviour of the rigid rotating body in liquid is used. The approach is based on the application of the Navier-Stokes motion eq., equation of continuity and boundary conditions eqs. It is possible to separate the motion of the rigid body and liquid from each other using suitable transformation relations and then it is also possible to separate the stationary and nonstationary motions from each other. A method of control volumes is used for these analyses. The real Bézier body is used for the description of the geometrical configuration and also for the approximation of velocity and pressure functions. Combined the ALE (Arbitrary Lagrange-Euler) method is used, because it´s necessary to generate a new net (to perform new meshing) for a change of the shaft position. The additional effects of the liquid (additional mass, stiffness and damping), which we solved in dynamic analysis, are the function of the single parameter only – the shaft-centre position. There is a large advantage in comparison with the standard approach, which is based on application of the Reynolds liquid eq. Author solving the models of the long and short journal bearing with different geometry, especially the elliptical and cylindrical bearings, with incompressible and compressible journal bearing liquid. If the journal bearing problem is solved, it is possible to include the additional effect of the liquid to the right side of the motion equation of a model rotor assembly. Author analyze a model rotor assemblies with two degrees of freedom, which is supported inside of the two journal bearings on the ends of the rotor (Jeffcott rotor assembly). Author modelling and solveing a response of the model rotor assembly on the forced steady-state vibrations, which was actuating by the unbalanced matter.
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Artificial heart on the principle of gas accumulators
Kunický, Ondřej ; Fialová, Simona (referee) ; Pochylý, František (advisor)
The diploma thesis deals with the design of an artificial heart based on the principle of gas accumulators. The introductory part describes the anatomy and physiology of the human cardiovascular system, mechanical heart replacement and the basic properties of pneumatic mechanisms. Furthermore, there is shown the procedure of pneumatic circuit design and its simulation in the program Simulink. The experimental part contains verification of the functionality of the pneumatic circuit, designed the positive displacement pump, and the measured characteristics of both ventricles. The last part of the work deals with the reduction possibilities of dimensions and weight of the whole mechanism. There is also included computational modelling of the pneumatic circuit using helium as a working medium.
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Computational modelling of stresses in intracranial aneurysms
Turčanová, Michaela ; Polzer, Stanislav (referee) ; Burša, Jiří (advisor)
The diploma thesis deals with the assessment of the prediction of brain aneurysm rupture based on its geometrical and material properties. In the first part of the thesis there is a~detailed research study of cardiovascular systems with a focus on the cerebral artery and aneurysm occurring on their bifurcates. The second part of the thesis is focused on the creation of two models of arterial cerebral bifurcation with the presence of aneurysm and on obtaining their geometry in unloaded state. Emphasis is placed on the most realistic constitutive model of the artery wall material based on real data from uniaxial tensile tests and on a suitably chosen blood pressure load. This blood pressure may be step-changed, for example, in bungee jumping. In the work, a calculation of the increase in blood pressure during the step-change is performed, which is subsequently used in calculations of tension in the wall of the cerebral aneurysm. In conclusion, the risk of rupture is evaluated in two model idealized brain aneurysms and a discussion of the credibility of the results is given.
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Application of tensegrity structures in modelling of mechanical behaviour of smooth muscle cells
Bauer, David ; Fuis, Vladimír (referee) ; Burša, Jiří (advisor)
The master’s thesis deals with the computational modelling of the mechanical testing of isolated smooth muscle cells. The main aims are to create computational model of a cell, to simulate single-axis tensile test and to modify the model so that the model reflects real mechanical response. The model of the cell includes cytoplasm, nucleus, cell membrane and cytoskeleton which is modelled as a tensegrite structure. On this model the tensile test was simulated in case of the cell with cytoskeleton and the cell with distributed the cytoskeleton. Force-elongation curves, which were obtained from this simulation, were compared with experimental data which were taken from literature. Tensile properties were measured on freshly isolated cells from rat thoracic aorta, cultured cells, and cells treated with cytochalasin D to disrupt their actin filaments. It was found that the cytoskeleton influence on the cell load in computational model was smaller than in the real cell. Therefore the model was modified by changing material propreties and geometry so that the model of the cell corresponded with the different types of experimentally measured cells.
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Overview to arterial stents and possibilities of their computational modelling
Ondříšková, Tereza ; Lisický, Ondřej (referee) ; Turčanová, Michaela (advisor)
This bachelor thesis deals with arterial stents and possibilities of their computational modelling. The thesis contains a medical minimum, which is necessary to understand the principle of arterial stents. Furthermore, the thesis is focused on methods of a stent implantation, materials used for manufacturing and covering and the most used designs. There is a research study of analytical and numerical computational modelling of them with emphasis on the finite element method. In the last part of this thesis there was performed an analytical calculation of stress appeared in the carotid artery wall after stent implantation using a simplified model of stent-artery configuration. Then these stress functions were plotted and evaluated.
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