Macro and Micro-indentation Behavior of the Cortical Part of Human Femur

AbstractBone is a nano bio-composite with collagen lamella impregnated with Hydroxyapatite nano crystals. This structural heterogeneity is known to influence its mechanical behavior. Previous studies have focused on mechanical properties in macroscopic level, mostly fracture behavior. In the present study, we performed macroindentation and depth sensitive indentation (DSI) to understand the deformation properties under various loads. Cortical bone tissues from human cadaveric femur were used for indentation study with loads varying from 10mN to 30N. Indentation size effect was observed for lower load range whereas reverse trend was found for loads >5N. Hardness in the interstitial zone was 14% higher than in lamellar region. Plasticity parameter obtained from DSI ranged from 0.61 to 0.69 which suggests there is little chance of pile up since 0.7 is the threshold value depicting pile-up phenomenon