PSI - Issue 45

Xiaochen Wang et al. / Procedia Structural Integrity 45 (2023) 88–95 Xiaochen Wang/ Structural Integrity Procedia 00 (2023) 000 – 000

94

7

the risk of rupture in AAA. 4. Conclusion

The current research aimed to examine the impact of ILT and anisotropy of the aneurysm wall on the mechanical responses in AAA via simulation. The use of FSI models allowed for a better understanding of the relationship between haemodynamics of the blood flow and failures of the AAA wall. To the best of author's knowledge, this study is a novel contribution as it is the first to integrate ILT into FSI models while incorporating realistic blood flow conditions and independently derived properties for both ILT and the AAA wall. The wall stress results showed that PWS are significantly impacted by the material models used, and the amount of thrombus present in the lumen also influences the wall stress in some extent. This can draw the conclusion that idealised model, ignoring the complexity of material and full geometries of the AAA, can lead to inaccurate predictions. This study shows the importance of incorporating ILT volume into clinical trials as a more sophisticated standard for assessing AAA rupture risk, beyond simply using the aortic diameter alone. These results pave the way for future clinical and computational efforts to better understand and predict the progression of AAAs and improve their management, which can potentially save lives. This study also highlights the importance of considering the orientation of collagen fibres and their properties with advanced anisotropic constitutive models, as it greatly influences the deformation and will thus significantly enhance the reliability of the finite element-based simulations. In this study, it should be acknowledged that the limitations associated with ignoring the multi-layered structure of the aortic wall and not incorporating patient-specific in vivo modelling could potentially impact the accuracy of the results. However, this study is a parametric study with the aim of examining the effects of different parameters rather than accurately representing a specific individual's condition. Given the nature and focus of this study, these limitations can be considered acceptable and do not significantly affect the overall conclusions. Aneurysmal degeneration involves remodeling at the microscale. Future work and investigations are needed on the understanding of micromechanics of the aortic wall fracture and material strength, which can assist in creating a patient-specific risk prediction models that can be used as a clinical adjunct for decision making. The results will guide future clinical and computational efforts towards understanding and predicting the progression of AAAs, and help improve the management of this potentially life-threatening condition. Acknowledgements The authors would like to acknowledge the support provided by The University of Adelaide. Xiaochen Wang is supported by a scholarship from the Department of Education, Skills and Employment Research Training Program (RTP) scholarship. This work was supported with supercomputing resources provided by the Phoenix HPC service at the University of Adelaide and acknowledges support from The University of Adelaide, School of Mechanical Acosta, S., Ögren, M., Bengtsson, H., Bergqvist, D., Lindbald, B., Zdanowski, Z., 2006. Increasing incidence of ruptured abdominal aortic aneurysm: A population-based study. Journal of Vascular Surgery, 44, 237-243. Amabili, M., Balasubramanian, P., Bozzo, I., Breslavsky, I. D., Ferrari, G. 2019. Layer-Specific Hyperelastic and Viscoelastic Characterization of Human Descending Thoracic Aortas. Journal of the Mechanical Behavior of Biomedical Materials, 99, 27-46. Amabili, M., Balasubramanian, P., Bozzo, I., Breslavsky, I. D., Ferrari, G., Franchini, G., Giovanniello, F., Pogue, C. 2020. Nonlinear Dynamics of Human Aortas for Material Characterization. Physical Review. X, 10, 011015. Avril, S., Badel, P., Duprey, A. 2010. Anisotropic and hyperelastic identification of in vitro human arteries from full-field optical measurements. Journal of Biomechanics, 43, 2978-85. Bantwal, A., Singh, A., Menon, A. R. & Kumar, N. 2021. Pathogenesis of atherosclerosis and its influence on local hemodynamics: A comparative FSI study in healthy and mildly stenosed carotid arteries. International Journal of Engineering Science, 167, 103525. Basciano, C. A., Kleinstreuer, C. 2009. Invariant-based anisotropic constitutive models of the healthy and aneurysmal abdominal aortic wall. Journal of Biomechanical Engineering, 131, 021009. Boyd, A. J. 2021. Intraluminal thrombus: Innocent bystander or factor in abdominal aortic aneurysm pathogenesis? JVS-Vascular Science, 2, 159 169. Engineering. References