Poroviscoelastic finite element model including continuous fiber distribution for the simulation of nanoindentation tests on articular cartilage

In order to simulate the mechanical response of articular cartilage under nanoindentation test, the axisymmetric model accounts for a depth-dependent mechanical properties. In particular, a porous matrix (MAT), a viscoelastic collagen network (COL) and the swelling effect due to the interspersed glycosaminoglycans (GAGs) are considered. The continuous ellipsoidal COL distributions vary layer by layers from fibers which are mainly parallel to the articular surface in superficial layers to fibers mostly perpendicular to the bone in deep layers.210