  Mineralized collagen microfibrils in human bone provide its mechanical
properties (stiffness, elasticity, ductility, energy dissipation and strength).
However, detailed 3D finite element models describing the mechanical behaviour
of the mineralized collagen microfibrils are still lacking. In the current
work, we developed a 3D finite element model of the mineralized collagen
microfibril that incorporates the physical 3D structural details. The model
components consist of five tropocollagen molecules, mineral hydroxyapatite and
intermolecular cross-links joining primarily the ends of the tropocollagen
molecules. Dimension, arrangement and mechanical behaviour of the constituents
are based on previously published experimental and theoretical data. Tensile
load was applied to the microfibril under different conditions (hydrated and
dehydrated collagen) to investigate the relationship between the structure and
the mechanical behaviour of the mineralized collagen microfibril (stress-strain
curve and elastic modulus). The computational results match the experimental
available data well, and provide insight into the role of the phases and
morphology on the microfibril behaviour. Our predicted results show that the
mechanical properties of collagen microfibrils arise due to their structure and
properties. The proposed 3D finite element model of mineralized collagen
microfibril contributes toward the investigation of the bottom-up
structure-property relationships in human bone.
