Abstract
A fiber reinforced poro-viscoelastic model is presented to investigate the mechanical properties of the meniscal tissue under several cyclic loading configurations. This constitutive model that implements fibers within an isotropic matrix allowed the consideration that the tissue’s mechanical behavior is anisotropic, which is consistent with the particular microstructural organization of the tissue. Furthermore, the implementation of viscoelastic effects allowed to describe the relaxation phenomena that characterize the meniscal tissue. This model made it possible to devise an inverse finite element method for estimating the mechanical properties of tissue subcomponents in dynamic shear loading, particularly of collagen fibers and ground substance. A first validation process with experimental results revealed that the constitutive model predictions are accurate in shear loading. Furthermore, the model was used in a parametric finite element analysis to investigate how the energy dissipation phenomena within the tissue are affected by the tissue health state and chemical composition, in cyclic compressive loading. The parametric analysis revealed that healthy menisci have a higher capability to dissipate energy compared to degenerated ones. The second validation process revealed that, in compressive loading the model accuracy decreases probably due to imprecisions in the implementation of compressive viscoelastic parameters. In summary, the analysis ran with this model made possible to increase the information about the pathophysiology of the meniscal tissue and allowed to devise a method to derive subcomponents mechanical parameters of importance for advanced multiscale modeling approaches.