Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Formulation of a biphasic model considering Donnan's osmotic pressure for investigations of the swelling phenomenon in soft tissues
Submission Author:
Rafael Geronimo , PR
Co-Authors:
Rafael Geronimo, Bruno Klahr, José Luís Medeiros Thiesen, Otávio Teixeira Pinto, Eduardo Fancello, Thiago André Carniel
Presenter: Bruno Klahr
doi://10.26678/ABCM.COBEM2023.COB2023-1162
Abstract
The biomechanical behavior of soft tissues evolves a series of biochemical phenomena that are directly related to the structures that compose the tissue, as well as the environment that it permeates. Tendons are highly hydrated and poorly vascularized connective tissues. Its morphological composition is mainly composed of an extracellular matrix formed by a combination of fibers (collagen and elastin) together with a ground substance constituted by a set of hydrophilic macromolecules. These molecules include glycosaminoglycans and proteoglycans. In addition to having various properties and performing different morphological functions, these molecules are also responsible for providing tissues with a negative electrochemical charge called fixed charge density (FCD). This property is directly related to a series of biochemical phenomena that influence the chemical and mechanical response of the tissue. Due to the presence of these macromolecules, an electrochemical imbalance is established, creating a potential difference called osmotic pressure. This osmotic pressure imposes a mechanical loading on the tissue, affecting on its kinematic responses and acting directly on the fluid flow. In many studies, triphasic models are commonly used to describe the biomechanical behavior of soft tissues under chemical loading. However, these models are quite complex and computationally costly. Alternatively, poroelastic biphasic models have been modified to include electrochemical effects in research where the variable of interest does not include the ionic field. In this case, instead of considering a third field (ionic), the models incorporate the osmotic pressure phenomenon through a local update of the total pressure term. In this context, the main objective of the present study is to use a poroelastic biphasic model to study the swelling phenomenon observed in tendon tissues when subjected to chemical stimuli. For this purpose, a poroelastic model has been developed that takes into account the osmotic pressure caused by chemical solicitation based on Donnan’s equation. The proposed model was implemented in an in-house finite element code and the results and accuracy of the model were compared with the FEBio software.
Keywords
Biphasic formulation, poroelasticity, Osmotic pressure, Finite Element Method, Soft Tissues Biomechanics
