|
| |
|
|
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.
|
|
|
London Eye
Hušek, Martin ; Hradil, Petr (referee) ; Zídek, Rostislav (advisor)
Performance of static analysis of the London Eye structure is the subject of this diploma thesis. First chapters of the thesis analyses overview of realized structures of the Ferris wheel. The main part of the thesis analyses the London Eye structure itself. Specifically are described response analyses, sensitivity analyses, analyses of ultimate limit state and serviceability, stress analyses, analyses of fatigue stress and lifetime analyses. The thesis describes among static analysis also a design of dynamic vibration absorbers. The results of each analysis are evaluated in the final chapters.
|
|
|
Analysis of the steel structure of the bridge by FEM to the action of static load
Skorunka, Ondřej ; Hradil, Petr (referee) ; Salajka, Vlastislav (advisor)
The structures of bridges are one of the most demanding engineering structures. They fulfill an important social and economic role in the development of the given territory. From this perspective, it is necessary to pay close attention to the process of design, analysis, realization and service. This thesis deals with the static analysis of spatially curved and asymmetrical suspended foot bridge for pedestrians and cyclists. The first part is devoted to the analysis of structural deformation, while the second part is focused on the analysis of selected parts of the structure in terms of its stress.
|
|
|
Analysis of state-of-art of modelling of atherosclerosis - review and computation
Polišenská, Anna ; Man, Vojtěch (referee) ; Novák, Kamil (advisor)
This Bachelor’s thesis contains a research of state-of-art of computational modelling of atherosclerosis using FEM. At first a medical terminology about atherosclerosis is described. Then the thesis is focused on nonlinear behaviour of the material such as hyperelasticity. It describes chosen constitutive models used for the stress-strain analysis of blood vessels. Within the thesis there is performed an idealized 2D analysis of stress in atherosclerotic common iliac artery. There are drawn and evaluated dependencies of necrotic core and fibrous cap thickness on maximal equivalent stress.
|
|
|
Variational Methods in Thermomechanics of Solids
Pelech, Petr ; Kružík, Martin (advisor) ; Dondl, Patrick (referee) ; Zeman, Jan (referee)
The thesis is devoted to study of continuum mechanics and thermodynamics and the related mathematical analysis. It consists of four self-contained chapters dealing with different aspects. The first chapter focuses on peridynamics, a non-local theory of continuum mechanics, and its relation to conventional local theory of Cauchy-Green elasticity. Similar compar- isons has been used for proving consistency and for determining some of the material coefficients in peridynamics, provided the material parameters in the local theory are known. In this chapter the formula for the non-local force-flux is computed in terms of the peridynamic interaction, relating the fundamental concepts of these two theories and establishing hence a new connection, not present in the previous works. The second and third chapters are both devoted to Rate-Independent Systems (RIS) and their applications to continuum mechanics. RIS represents a suitable approximation when the internal, viscous, and thermal effects can be neglected. RIS has been proven to be useful in modeling hysteresis, phase transitions in solids, elastoplasticity, damage, or fracture in both small and large strain regimes. In the second chapter the existence of solutions to an evolutionary rate-independ- ent model of Shape Memory Alloys (SMAs) is proven. The model...
|
|
|
Variational Methods in Thermomechanics of Solids
Pelech, Petr ; Kružík, Martin (advisor) ; Dondl, Patrick (referee) ; Zeman, Jan (referee)
The thesis is devoted to study of continuum mechanics and thermodynamics and the related mathematical analysis. It consists of four self-contained chapters dealing with different aspects. The first chapter focuses on peridynamics, a non-local theory of continuum mechanics, and its relation to conventional local theory of Cauchy-Green elasticity. Similar compar- isons has been used for proving consistency and for determining some of the material coefficients in peridynamics, provided the material parameters in the local theory are known. In this chapter the formula for the non-local force-flux is computed in terms of the peridynamic interaction, relating the fundamental concepts of these two theories and establishing hence a new connection, not present in the previous works. The second and third chapters are both devoted to Rate-Independent Systems (RIS) and their applications to continuum mechanics. RIS represents a suitable approximation when the internal, viscous, and thermal effects can be neglected. RIS has been proven to be useful in modeling hysteresis, phase transitions in solids, elastoplasticity, damage, or fracture in both small and large strain regimes. In the second chapter the existence of solutions to an evolutionary rate-independ- ent model of Shape Memory Alloys (SMAs) is proven. The model...
|
|
|
Numerical modelling of vocal folds
Michálek, Jakub ; Velímský, Jakub (advisor) ; Hron, Jaroslav (referee)
Title: Numerical modelling of vocal folds Author: Mgr. Bc. Jakub Michálek Department: Geophysics Department Supervisor: RNDr. Jakub Velímský, Ph. D., Geophysics Department Abstract: I created a 2D model of vocal fold oscillations driven by interaction with fluid flow (FSI model). I used the theory of finite strains of the structure. The flow was modelled as a viscous incompressible fluid. The numerical problem was solved by the finite element method (FEM) with the arbitrary Lagrangian- Eulerian (ALE) method. The model shows the regime before phonation without the contact of the vocal folds and the states that directly lead to the contact of the vocal folds. I compared the time dependence of the quantities measured at sensors attached to the folds. I measured the frequency characteristics and compared the results with the modal analysis. Consequently, I calculated a parametric study of the dependence of the oscillations on the inlet air velocity, the original distance of the vocal folds and the elasticity of the vocal folds. The parametric study confirms that a sufficient increase of the inlet air velocity and a sufficient constriction of the glottis lead to the phonation onset. The parametric study also shows that changing elastic parameters has a similar effect on the spectrum for both the FSI model and the modal...
|
|
|
Analysis of state-of-art of modelling of atherosclerosis - review and computation
Polišenská, Anna ; Man, Vojtěch (referee) ; Novák, Kamil (advisor)
This Bachelor’s thesis contains a research of state-of-art of computational modelling of atherosclerosis using FEM. At first a medical terminology about atherosclerosis is described. Then the thesis is focused on nonlinear behaviour of the material such as hyperelasticity. It describes chosen constitutive models used for the stress-strain analysis of blood vessels. Within the thesis there is performed an idealized 2D analysis of stress in atherosclerotic common iliac artery. There are drawn and evaluated dependencies of necrotic core and fibrous cap thickness on maximal equivalent stress.
|
|
|
2D finite element formulation of elastic string vibrations with large displacements
Michálek, Jakub ; Horáček, Jaromír (advisor) ; Matyska, Ctirad (referee)
The thesis addresses the numerical solution of the oscillation of the vocal fold at finite strain, whereas the literature has so far been concerned with infinitesimal strain only. The geometry concerned corresponds to the easiest situation of falsetto, since we observe an isolated vocal fold. The vocal fold is treated as non-linear and non-isotropic continuum in 2D space. To demonstrate the function of the model, we simulate the behaviour of the vocal fold with the linear constitutive equation numerically. The vocal fold is modelled by the finite element method with quadratic elements for static and dynamic surface load. We show that a proper simulation of vocal fold tissue deformation requires the equations with finite strain term. Numerical simulation of the vocal fold can be used e.g. for the construction of artificial vocal folds, and for the optimization of their function. Understanding the phonatory mechanism is also essential for discovering the causes of the disorders such as the vocal nodules and for the scientific foundation of phoniatrics and education of singers. The thesis is interdisciplinary and synthesises the facts from mechanics of continuum, anatomy and education of singers.
|
guest ::
