Influence of strain rate on the mechanical behavior of cortical bone interstitial lamellae at the micrometer scale

Investigations of bone mechanical properties are of major importance for bone pathology research, biomaterials, and development of in vivo bone characterization devices. Because of its complex multiscale structure, assessment of bone microstructure is an important step for understanding its mechanical behavior. In this study, we have investigated the strain rate influence on the mechanical properties of interstitial lamellae on two human femur bone samples. Nanoindentation tests were performed with the continuous stiffness measurement technique. Young's modulus and hardness were calculated using the Oliver and Pharr method. A statistical significant influence of strain rate on hardness was found (p < 0.05) showing a viscoplastic behavior of interstitial bone at the micrometer scale. This phenomenon may reflect the role of the organic component in the bone matrix mechanical behavior.