Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
FINITE ELEMENT SIMULATION AND PERFORMANCE ANALYSIS OF A NOVEL BIOABSORBABLE STENT FOR THE TREATMENT OF AORTIC COARCTATION
Submission Author:
Flávio Santos , SP
Co-Authors:
Flávio Santos, Bruno Agostinho Hernandez, Mateus Piccin Duarte de Souza, Aron Andrade, EDSON CAPELLO SOUSA
Presenter: Flávio Santos
doi://10.26678/ABCM.COBEM2021.COB2021-0131
Abstract
The Finite Element Method (FEM) has been frequently applied in biomechanics, as it is a reliable tool to analyse complex structures. However, the development of a biomechanical model is not a trivial task, as it frequently requires non-linear interactions, non-symmetrical geometries, and variable mechanical properties. Coarctation of the Aorta (CoA) is a congenital heart disease that causes a narrowing in the artery cross-section area, partially reducing the blood flow. One of the most traditional treatments for CoA is the use of metallic stents. However, their use in young children is limited, due to the patient’s constant growth and the need for new surgeries for stent expansion, which it is only possible up to a certain diameter. In this scenario, the development of a bioabsorbable stent for the treatment in children was idealised, as these devices degrade over time and remain temporarily in the patient's body. Therefore, this study aimed to develop a finite element model of a bioabsorbable stent, simulate its opening of an artery with coarctation, and evaluate which modelling parameters influence the model’s performance. A new stent geometry was developed by the Adib Jatene Foundation and modelled on the SpaceClaim module (ANSYS Inc., USA). Geometries of a healthy and a coarctated aortic artery were also created. The material set for the stent was PLLA (Poli-L-Lactide-Acid), with a linear elastoplastic material model; the aorta was defined as hyperelastic. To analyse the mechanical behaviour of the new stent geometry, initial simulations in ANSYS were conducted with the stent defined as made of steel. The isolated stent was expanded, from a diameter of 6.25mm to 15mm. In a second phase, the stent material was changed to PLLA, and a healthy artery was included in the model - the stent was again expanded to 15mm. Finally, a coarctated artery was introduced and the process repeated. The analysed parameters were the type/size of the element, type of loading (pressure/displacement), number of loading steps and sub-steps, and type of coordinate system. It was found that the application of loading by displacement and a change from the Cartesian to the cylindrical coordinate system resulted in a better simulation performance, with the stent achieving the maximum opening. The developed model allowed a representation of the structural behaviour of a new bioabsorbable stent inside an artery with coarctation, and an evaluation of the stent's performance during its implantation as well as the main parameters affecting the modelling.
Keywords
Coarctation of the Aorta (CoA), Finite Element Method, Bioabsorbable Stents
