Analiza naprezanja na aneurizmi abdominalne aorte

undergraduate thesis

• Title (english): Stress analysis of abdominal aortic aneurysm
• Author: Adriana Čorić
• Mentor: Igor Karšaj (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2017-03-02, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

Aneurizma abdominalne aorte lokalizirano je proširenje abdominalne aorte i bolest je koja se razvija tijekom razdoblja od nekoliko desetaka godina, a česta komplikacija bolesti je ruptura aneurizme. Liječenje aneurizme svodi se na operativni zahvat, koji se preporuča ukoliko je maksimalni promjer aneurizme veći od 5-5,5 cm ili ako aneurizma raste brže od 1 cm/god. Operativni zahvata nosi sa sobom određene rizike, naročito jer je aneurizma bolest koja pretežno zahvaća stariji dio populacije. Tijek bolesti može se pratiti CT uređajem ili ultrazvukom, a u sklopu ovog rada nastoji se iz tako dobivenih snimaka, odnosno pripadne geometrije, koristeći metodu konačnih elemenata, analizirati raspodjelu naprezanja na stijenci aneurizme za pojedinog pacijenta. Analiza se provodi koristeći dva različita materijalna modela implementirana unutar programskog paketa Abaqus – izotropni Neo-Hooke model i anizotropni Holzapfel-Gasser-Ogdenov model. Za anizotropan Holzapfel-Gasser-Ogdenov model definiraju se orijentacije kolagenih vlakana za pojedini segment geometrije. Tako dobiveni rezultati uspoređuju se s izotropnim Neo-Hooke modelom. Na temelju provedenih analiza procjenjuju se kritična mjesta na kojima bi moglo doći do rupture te se ispituje povećanje volumena aneurizme kao mogući operativni kriterij. Također, analiziraju se naprezanja na aneurizmi uzrokovana povišenim krvnim tlakom, što je jedan od značajnih čimbenika koji mogu uzrokovati rupturu.

Abstract (english)

Abdominal aortic aneurysm is localized dilatation of abdominal aorta. It expands over several decades but ruptures abruptly when wall stress exceeds wall strength. Aneurysms can be treated only surgically. Surgical treatment is recommended in cases when the maximal diameter of aneurysm is greater than 5-5,5 cm or the aneurysmal expansion rate is greater than 1 centimeter per year. Considering that the disease mostly affects the elderly surgery introduces its own risks. In the case surgery is not necessary progress of the disease can be monitored by a CT scanner or an ultrasound machine. In the context of this thesis stress distribution is analyzed on the 3D geometry generated from CT scans of a patient with 5 follow-ups. For the calculation of stresses finite element method is used. Two material models implemented in Abaqus (isotropic Neo-Hooke and anisotropic Holzapfel-Gasser-Ogden model ) have been applied for this analysis. For the Holzapfel-Gasser-Ogden model orientation of the collagen fibers is defined for separate partitions of geometry. Results of anisotropic analysis are then compared with the results obtained using Neo-Hooke model. Based on those analyses the expected locations of rupture are assessed. Furthermore, stress analysis of abdominal aortic aneurism is conducted for multiple cases of elevated blood pressure, which is identified as one of the considerable factors causing an aneurysm rupture.

• Keywords: abdominal aortic aneurism; finite element method patient-specific geometry; anisotropy; Abaqus
• Keywords (english): aneurizma abdominalne aorte; metoda konačnih elemenata; geometrija svojstvena pacijentu; anizotropija; Abaqus
• Language: croatian
• URN:NBN: urn:nbn:hr:235:197463
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 19:21:51