POROHYPERELASTIC-TRANSPORT-SWELLING THEORY, MATERIAL PROPERTIES AND FINITE-ELEMENT MODELS FOR LARGE ARTERIES

A porohyperelastic-transport-swelling (PHETS) model is presented in wh ich a soft hydrated tissue material is viewed as a continuum composed of an incompressible porous solid (fibrous matrix) that is saturated b y an incompressible fluid (water) in which a mobile species (solute) i s dissolved. This PHETS theoretical model is implemented using a finit e element model (FEM) including inherent nonlinearity, coupled transpo rt processes, and complicated geometry and boundary conditions associa ted with soft tissue structures; The PHETS material properties are cle arly identified with a physical basis describing and quantifying elast icity, permeability, diffusion, convection, and osmotic properties. Th e equivalence between the PHETS and the triphasic (TRI) model (Lai et al., 1991) is established using the phenomenological equations, and ma thematical expressions are given to relate the PHETS and TRI material properties. A principle of virtual velocities (PW) links Eulerian and Lagrangian PHETS formulations and provides correspondence rules betwee n the Eulerian and the Lagrangian field variables and material propert ies. The PW is also the basis for a mixed Lagrangian PHETS FEM (Kaufma nn, 1996), which was developed for the analysis of soft hydrated tissu es. Selected PHETS FEM results are presented in order to demonstrate t he capability of the PHETS model to simulate coupled deformation, stre ss, mobile water flux, and albumin flux in the arterial wall undergoin g finite straining associated with pressurization, axial stretch, and changes in albumin concentration in bath solutions surrounding a segme nt of rabbit thoracic aorta. Values for isotropic material parameters and specific details of the experiments and data-reduction methods wer e obtained from Simon et al. (1997; 1998). (C) 1998 Elsevier Science L td. All rights reserved.