Indentation Simulation of Ovariectomized Sheep Bone Using a Viscoelastic/Plastic Damage Model

Indentation techniques have become a standard method to assess the mechanical properties of numerous materials. In recent years, nanoindentation of bone has been used to extract the mechanical behavior at the level of osteons and lamellae. Under a transmitted light microscope, small microcracks can be observed in cortical bone, and breakage of trabeculea can be observed in trabecular bone. These cracks are implicated in physiological phenomena including stress fractures, bone remodeling, and adaptation. Together, these material discontinuities can be considered as damage. Damage accumulation of bone is generated through daily mechanical loading, and then recovered during remodeling. For bone indentation modeling, even though pre-existing damage may be neglected in most cases, new damage can also be produced during the process of testing. Thus, damage accumulation needs to be considered when establishing a nanomechanical bone model.