A three-dimensional multiscale finite element model of bone coupling mineralized collagen fibril networks and lamellae.

Despite evidence of contribution of mineralized collagen fibrils (MCF) to both the microscale elastic and fracture response of bone, the extent of influence of MCF orientation and material property variation on the lamellar scale mechanical properties is still not well quantified. To this end, in this study, we developed a three-dimensional multiscale finite element model that linked submicroscale models of MCF networks to microscale models of several lamellae. The developed models evaluated the individual and relative influence of MCF orientation as well as material property variation due to MCF mineral distribution and interaction on the lamellar scale mechanical response of bone. The simulation results showed that the elastic modulus, ultimate strength, and fracture energy at the lamellar scale decreased as the angle between the main axis of MCFs and loading direction increased. The heterogeneity in mineral distribution along MCFs did not lead to a significant difference in the mechanical behavior at the lamellar scale compared to the material property heterogeneity introduced in the models due to MCF orientation variation. Variation in the interaction between MCFs at the submicroscale had a substantial influence on the lamellar scale mechanical properties. In summary, this study established a multiscale model that linked MCFs to lamellae providing the capability of quantifying the relative influence of modifications in material and organizational properties of MCFs due to age, diseases, and treatments on the fracture processes at the lamellar length scale.