The aim of this thesis is the problematic of abdominal aortic aneurysm wall stress in relation to a different material behavior of intraluminal thrombus, which is in most cases present in the aneurysmal volume. In this thesis, the influence of neglecting the patient-specific material properties of the intraluminal thrombus, on the aneurysmal wall stress, obtained from finite element stress-strain analysis, is investigated. In terms of solution method selection, a system approach was applied so that the solution method was selected in order to respect a system of essential variables as much as possible. The first part of this thesis is focused on a description of the problematic and the human cardiovascular system with important aspects contributing to development and growth of the abdominal aortic aneurysm. Next, this part of the thesis includes chapters devoted to the intraluminal thrombus in terms of its basic characteristics (anatomy, physiology, pathology), structure and its influence on processes within the abdominal aneurysm. The second part of this work is devoted to the accomplishment of the first and second goal of this thesis, which is analyzing the available literature to obtain mean population stiffness values of the intraluminal thrombus and conducting biaxial experimental tests of provided samples of intraluminal thrombus. The experimental testing was conducted in order to obtain the patient-specific mechanical properties, which are used as the inputs in the finite element analysis. The experimental testing confirmed the stiffness negligibility of the intraluminal thrombus’s outer layer, which is mentioned is several studies, however, the influence of this layer on resulting aneurysmal wall stress has been to this date not tested. The dominant part of this thesis is focused on the third goal of this work, which is a comparison of aneurysmal wall stress obtained from the finite element computation that included mechanical properties of intraluminal thrombus obtained either from the literature analysis of experimental testing. This part includes discerption of idealized geometry model development, which was used to analyze the sensibility of computed stresses on a number of ILT layers representing different material properties. In order to obtain this analysis, a macro was created prescribing each element of the intraluminal thrombus finite element mesh with material properties derived from its distance from the lumen. Next, this chapter contains description of patient-specific geometry models development, material models, and boundary conditions selection. In the end of this part, results of the finite element computations are presented together with their statistical analysis. Within the last part of this thesis, discussion of results and conclusions of this thesis is included. Also, an overview of important aspects entering computational modeling of abdominal aortic aneurysms is presented.
| Identifer | oai:union.ndltd.org:nusl.cz/oai:invenio.nusl.cz:318678 |
| Date | January 2017 |
| Creators | Hřičiště, Michal |
| Contributors | Novák, Kamil, Polzer, Stanislav |
| Publisher | Vysoké učení technické v Brně. Fakulta strojního inženýrství |
| Source Sets | Czech ETDs |
| Language | Czech |
| Detected Language | English |
| Type | info:eu-repo/semantics/masterThesis |
| Rights | info:eu-repo/semantics/restrictedAccess |
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