ABSTRACT
This chapter focuses on the finite element formulation and on numerical simulations of mechanical and chemical loading processes. Sun et al. were the first to develop a finite element formulation which accounts for the fact that many physical entities, like ionic concentrations, fluid pressures, etc. are discontinuous at the boundary of the cartilage specimen. This observation constrains the choice of primary variables. In fact, the prospect of simplifying the electro-chemomechanical coupled behavior of soft tissues with fixed electrical charge was considered previously by Lanir. Articular cartilages sustain load through electro-chemomechanical couplings that limit the magnitude of the strains. Because of the presence of the electrically charged proteoglycans, a number of physical entities are discontinuous at the interface between the cartilage and the bath.
