Finite element simulations of the electro-chemo-mechanical behavior of articular cartilage. Part II: results and discussion

In the present work, the finite element formulation and program presented in part I of this paper, are used to numerically simulate the response of an articular cartilage sample to a combination of chemical and mechanical actions. In the simulations, a sample of articular cartilage, laterally confined, is immersed in a bath of variable chemical composition always assuming the existence of electro-chemical equilibrium at the tissue-bath interface. Nonetheless, inside the tissue, the equilibrium is not attained instantaneously. In fact, the time needed to establish a steady state depends on the problem geometry and on some material properties, namely the percolation and diffusion times associated with Darcy's and Fick's laws, respectively. A good agreement is obtained between the results of the present model and previous experimental data in the case of a homogeneous bath. As another new feature of the model, results are also obtained when the tissue is immersed in a bath which allows each of the sample extremities to experience distinct variations of the chemical composition, which gives a closer insight to the tissue's behavior under a more diverse environment