In English

Fluid-Structure Interaction analysis of the forces causing stent graft migration

Patrik Andersson ; Johan Pilqvist
Göteborg : Chalmers tekniska högskola, 2011. 71 s. Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, ISSN 1652-8557, 2011.
[Examensarbete på avancerad nivå]

Abdominal aortic aneurysm, a disorder involving a local dilatation of the ab- dominal aortic vessel, is a disease common among males in their late sixties and a major cause of death in case of rupture. An aneurysm can be treated with major open surgery or with minimally invasive techniques. One such treatment, called En- dovascular Aortic Repair (or EVAR), is the insertion of stent grafts redirecting the blood flow through a bifurcating tube consisting of a special fabric supported by a reinforcing metallic mesh. This procedure is preferrable in the sense that it does not require an open surgery. However, there are some problems arising from the fact that the stent graft is not fixated at its lower extremities. When subjected to a pulsating blood flow the bifurcating portions of stent graft may thus experience detachment from the vessel walls (commonly referred to as stent graft migration), leading to fatal blood leakage. The forces causing such detachments are therefore of great interest. The development of numerical methods for Fluid-Structure Interaction (FSI) analyses provides possibilities to study the flow through a stent graft and the forces it exerts on the attachment regions. This report presents the results from FSI sim- ulations using the two softwares LS-DYNA and OpenFOAM. The scenarios studied in this work include a steady flow of water and a sinusoidal flow of water through a bent, flexible tube resembling one of the lower extremities of a stent graft. The dif- ferent softwares utilize different numerical approaches to formulate the FSI problem. LS-DYNA uses a Finite Element (FE) based Arbitrary Lagrangian-Eulerian (ALE) formulation, while OpenFOAM uses the Finite Volume (FV) method. In addition to the flow analysis and extraction of the forces, the use of the different softwares allows for a comparison between the two numerical approaches. For both scenarios, the flow characteristics in the different softwares show fair cor- respondence and the extracted forces are of the same orders of magnitude. However, some previous studies, such as the work performed by Li and Kleinstreuer [1], point towards larger forces than those extracted in this work. These differenes are likely to originate from the differences in geometries, material properties and boundary conditions. Nonetheless, the results show good promise for continuation of similar studies in the future.

Nyckelord: Abdominal Aortic Aneurysm, Stent Graft, FSI, OpenFOAM, LS-DYNA

Publikationen registrerades 2011-06-28. Den ändrades senast 2013-04-04

CPL ID: 142522

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