Modelling the micro-damage process zone during cortical bone fracture

Cortical bone employs intrinsic toughening mechanisms to delay crack growth initiation and propagation hence increasing its fracture toughness. Computational models of the bone fracture process though do not explicitly capture these intrinsic local toughening mechanisms. Such models could provide insights into possible sub-microscale mechanisms involved in the bone fracture process. Therefore, in this study, the intrinsic toughening mechanism referred to as the micro-damage process zone (MDPZ) was modelled using a bi-linear continuum damage law. This model was then experimentally validated using single edge notch bending specimens and digital image correlation for strain field measurements. The size and shape of the micro-damage process zone as well as the load-deflection curves generated by the model reasonably replicated those measured experimentally. The results indicate that the continuum damage mechanics approach is a robust means of modelling the MDPZ at the continuum level and with further development of the model can provide a useful tool for studies of the fracture process in cortical bone.