Abdominal Aortic Aneurysms (AAA) present a significant health risk due to the risk of rupture, leading to life-changing and potentially fatal complications. Endovascular aneurysm repair (EVAR) using stent grafts has become the preferred treatment method due to its minimally
invasive nature. However, long-term complications including graft migration, endoleaks and
thrombosis continue to occur and often require reintervention. This thesis investigates the mechanical behaviour of the woven biofabric used in stent grafts and its influence on the overall
performance of endovascular devices, with a particular focus on fabric deformation, device
stiffness, and fluid flow disruption.
A comprehensive experimental characterisation of the woven bio-fabric was conducted,
including testing in the tensile, shear, and bending directions to determine the fabrics mechanical properties under loaded conditions, creating a solid framework for future fabric studies.
Finite element models (FEA) were developed through bespoke material models, previously
not utilised within the field, and validated to simulate the interaction between the fabric and
the nitinol ring scaffold, capturing the complex deformation of the stent graft. Experimental
studies in representative stent graft devices assessed axial and bending stiffness through novel
methods which open up new avenues in stent graft design and reveal the influence of the fabric
properties on the flexibility and conformance to the arterial wall.
To further evaluate the impact of fabric deformation on haemodynamics, computational
fluid dynamics (CFD) simulations were performed, integrating patient-derived geometric variations and in vivo pressure conditions. The study analysed key haemodynamic parameters such
as wall shear stress (WSS), recirculation zones, low flow regions, and other relevant factors
linked to the formation of thrombus. The findings highlighted the role of fabric deformation in
altering local flow conditions.
The research outcomes contribute to the advancement of stent graft design by providing a
detailed understanding of the mechanical and fluid dynamics within endovascular devices. The
developed modelling framework improves the predictive capabilities for device performance,
helping in the development of the next generation of stent grafts with improved hemodynamic
efficiency. These insights have direct implications for clinical practice, offering strategies to
improve long-term patient outcomes and following EVAR procedures and reduce postoperative
complications.
| Date of Award | 22 Sept 2025 |
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| Original language | English |
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| Awarding Institution | - University Of Strathclyde
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| Sponsors | University of Strathclyde |
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| Supervisor | William Dempster (Supervisor) & David Nash (Supervisor) |
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