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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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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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Analysis of direction dispersion of collagen fibers in soft tissues
Sádovská, Terézia ; Lisický, Ondřej (referee) ; Turčanová, Michaela (advisor)
The bachelor thesis deals with the directional distribution of collagen fibres in soft tissues especially in arteries and tendons. The first part gives basic information about anatomy of human vascular system, particulary structure of the arteries. There are explained polarization microscopy principle of materials exhibiting birefringence. Further is described relation between direction of density and mechanical properties expresses as modulus in tensile. In the next section, we will be defined stress in arterial wall using linear stregth and stiffness. In the last part of thesis will be observed dispertion of collagen fibres in tendon. This dispertion is described by circular distribution Von Mises. At the end is evaluated how dispertion of collagen fibres effects mechanical properties of arteries.
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Analysis of possibilities of analytical approaches suitable for evaluating of stress-strain states of idealized aortic shapes
Turčanová, Michaela ; Burša, Jiří (referee) ; Novák, Kamil (advisor)
The bachelor's thesis deals with possibilities of analytical solution of stress-strain states of arteries. The first part of the thesis gives an information about cardiovascular system and continuum mechanics. The calculation was performed analytically and also numerically using ANSYS program. The analytical calculation was carried out considering non-linear theory of thin and thick-walled vessels involving the residual stress and fictitious temperature approach. Furthermore, the analysis of solutions of abdominal aortic aneurysms was done based on linear theory. Description of other methods of linear theory and techniques of calculating with residual stress are briefly summarized.
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ANALYSES OF STRUCTURE OF COLLAGEN FIBRES IN ARTERIAL WALL USING MODERN METHODS OF LIGHT MICROSCOPY
Turčanová, Michaela ; Kochová, Petra (referee) ; Hampl, Aleš (referee) ; Burša, Jiří (advisor)
The doctoral thesis deals with the analysis of the arrangement of collagen fibres in arteries and their correct evaluation and use in structurally motivated constitutive models of the material. The first part of the work is focused on the literature search of mechanical properties of arteries and on an overview of available methods for the detection of waviness, orientation and dispersion of fibres. Most works identify fibre angles as additional parameter from mechanical tests and thus degrade the structural nature of the model. The second part describes an automatic algorithm that can evaluate the local directions of fibres and their scattering from images from a polarizing microscope and structurebased hyperelastic constitutive models. Furthermore, there is an emphasis on choosing the most appropriate imaging method based on fluorescence microscopy, which will help us to distinguish the waviness and scattering of fibres. In the next part of the thesis, two experiments on porcine arteries are presented in order to determine the influence of different magnitudes of biaxial deformation on fiber orientation and dispersion. The last part of the work presents the evaluated structural parameters for porcine and human aortas, which were analyzed not only under polarized light, but also under a laser scanning confocal microscope, thanks to which the waviness of the fibers and their global direction were obtained.
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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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|
|
Analysis of direction dispersion of collagen fibers in soft tissues
Sádovská, Terézia ; Lisický, Ondřej (referee) ; Turčanová, Michaela (advisor)
The bachelor thesis deals with the directional distribution of collagen fibres in soft tissues especially in arteries and tendons. The first part gives basic information about anatomy of human vascular system, particulary structure of the arteries. There are explained polarization microscopy principle of materials exhibiting birefringence. Further is described relation between direction of density and mechanical properties expresses as modulus in tensile. In the next section, we will be defined stress in arterial wall using linear stregth and stiffness. In the last part of thesis will be observed dispertion of collagen fibres in tendon. This dispertion is described by circular distribution Von Mises. At the end is evaluated how dispertion of collagen fibres effects mechanical properties of arteries.
|
|
|
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.
|
|
|
Analysis of possibilities of analytical approaches suitable for evaluating of stress-strain states of idealized aortic shapes
Turčanová, Michaela ; Burša, Jiří (referee) ; Novák, Kamil (advisor)
The bachelor's thesis deals with possibilities of analytical solution of stress-strain states of arteries. The first part of the thesis gives an information about cardiovascular system and continuum mechanics. The calculation was performed analytically and also numerically using ANSYS program. The analytical calculation was carried out considering non-linear theory of thin and thick-walled vessels involving the residual stress and fictitious temperature approach. Furthermore, the analysis of solutions of abdominal aortic aneurysms was done based on linear theory. Description of other methods of linear theory and techniques of calculating with residual stress are briefly summarized.
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