Study of mechanical potentials to describe the biphasic mechanical behavior of fiber-reinforced soft tissues

Resumo

Soft tissues have a considerable percentage of their weight constituted of fluid, which directly impacts
its mechanical behavior. An appropriate formulation for describing this type of material is found in the biphasic
theory. However, although the mechanical potentials used in the literature have no difficulties in reproducing
the force response of the tissue, these potentials may also contradict experimental observations about the volume
change and fluid flow in traction. This work investigates a biphasic framework with an anisotropic hyperelastic
model in which the volumetric deformations are related to the extension of the fibers in the tissue through the
control of the Poisson’s ratio. In order to highlight the characteristics of this model, a experimental relaxation
test of tendon is adjusted using the force and Poisson ratio as variables, and a comparison using a viscoelastic
model is made. The results demonstrate the ability of the studied potential, together with a biphasic framework, to
represent volumetric, dissipative and fluid flow characteristics in the tendon. The results also show that the classic
viscoelastic model may not be appropriated in these aspects, demonstrating that characterization of the tissue using
only the force response may not guarantee an adequate characterization.