Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Difficulties and benefits of modeling the Achilles tendon using FEM
Submission Author:
Otávio Teixeira Pinto , SC
Co-Authors:
Otávio Teixeira Pinto, Bruno Klahr, José Luís Medeiros Thiesen, Thiago André Carniel, Eduardo Fancello
Presenter: Otávio Teixeira Pinto
doi://10.26678/ABCM.COBEM2023.COB2023-1204
Abstract
The Achilles tendon is known to be made of three subtendons, one from each of the three heads of the triceps surae muscle. The proper inclusion of the mechanics of the mesostructure of these three subtendons and the force transference among them is decisive to represent the non uniformity in the stress and strain fields of the Achilles tendon. Such non uniformity can be caused or the cause of abnormalities such as: tendinopathies, calcifications, presence of scar tissue and calcifications. The understanding of the precise level of impact of such abnormalities in the mechanical behavior of the Achilles tendon could impact on the decision making process of physiotherapists, physicians and PE professionals and for that goal a model of the Achilles tendon using FEM is proposed The model represents the tendon as an elliptical cylinder where the two semi-axis vary as a function of the position of a given ellipse in the cylinder axis. Internally the mesostructure was represented as a division of the domain in four parts, the three subtendons and an interface of finite thickness separating the subtendons. The subtendons twist around the cylinder axis. A transversely isotropic hyperelastic material model was used to represent the subtendons material. Two different levels of subtendon twist and three different levels of shear resistance for the interface were compared among themselves and with experiments from the literature. 27 different sets of boundary conditions were tested for each model in order to properly represent the experiments. The comparisons with the experiments are expected to show a better fit for the model with the most shear resistance since the experiments were made with human tendons from subjects 72-86 years old. Age is known to increase the internal shear resistance of connective tissues. There is no prediction of which level of twisting will better fit the experimental data, but there is some evidence that higher levels of twisting are associated with more uniform strain fields. The difficulties and potential benefits of the model are discussed extensively.
Keywords
Achilles tendon, FEM, Soft Tissues, hyperelastic anisotropic
