DIRECTION-DEPENDENT ELASTIC AND INELASTIC MECHANICAL RESPONSE OF CORTICAL BONE INVESTIGATED THROUGH NANOINDENTATION TESTING AND FINITE ELEMENT SIMULATIONS

In this work, a finite element model was developed for the numerical simulation of nanoindentation tests on cortical bone. The model takes into account the anisotropic elastic and post-yield behavior of the tissue. A tension-compression yield stress mismatch and a direction-dependent yield stress are allowed for. Indentation experiments along the axial (the longitudinal direction of long bones) and transverse directions have been compared with the results of the simulations. The transverse to axial mismatch of both indentation moduli and hardness observed in experimental studies can be correctly simulated through the proposed anisotropic yield constitutive model.