Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
Numerically assessing the impact of different hyperelastic laws on the mechanical response of intracranial aneurysms walls
Submission Author:
Iago Lessa Oliveira , SP , Canada
Co-Authors:
Iago Lessa Oliveira, Carlos Baccin , José Luiz Gasche
Presenter: Iago Lessa Oliveira
doi://10.26678/ABCM.ENCIT2022.CIT22-0188
Abstract
Intracranial aneurysms (IAs) — a dangerous disease affecting up to 10 % of the world’s population and with up to 50 % mortality rate, in case of rupture — is characterized as a dilatation of the cerebral arteries walls and, biologically, their walls fit within the class of soft tissues. Numerical studies on the rupture of an IA have become increasingly popular, but the correct constitutive model of its wall tissue, normally assumed to be an incompressible hyperelastic material, is essential to provide meaningful results. A couple of hyperelastic laws were already used to investigate IAs wall motion by a few works, and no answer on the most suitable one exists, although the majority of the works on the subject used laws that do not represent the finite-deformation regime of the motion of soft tissues, such as the classic Hookean law. Hence, in this work we aim at investigating the effect of different hyperelastic laws on the mechanical response of patient-specific IAs. Pulsatile numerical simulations were carried out using the one-way fluid-solid interaction solution strategy implemented in solids4foam, an extension of OpenFOAM®, in which the blood flow is solved and applied as the driving force of the wall motion. Two patient-specific IA surface models were obtained from medical examinations (approved by the ethical committees of the institutions involved) using the Vascular Modeling Toolkit®. The IA and artery walls were assumed isotropic and their thickness and material properties were computationally created using a “hemodynamics-driven” approach in which both thickness and material constants were computed a priori, depending on the cardiac-cycle averaged hemodynamics adjacent to the IA wall. Three hyperelastic laws, suitable for soft tissues, were employed to assess the influence of different models: the Yeoh law, the three-parameter Mooney-Rivlin law, and a Fung-like law with a single parameter. Preliminary results suggest that the three hyperelastic laws produce similar mechanical responses, in terms of stresses and stretches, although the difference among them change along the thickness of wall. This fact could be used to guide modeling decisions on IA simulations, since the computational behavior of each law were different, with the Yeoh law yielding the smallest computational time.
Keywords
Intracranial aneurysms, aneurysm wall constitution, hyperelasticity, solids4foam
