Mechanical properties and structural behavior of bone at nano scale with cohesive element

Bone is a mineralized biological tissue whose main components are enormously different from the mechanical aspect. Some of bone diseases like osteoporosis are due to mutations in bone structure at nano scale, while their clinical symptoms usually appear at macro scale. Therefore, the evaluation of bone at micro and nano scales is important and the obtained results could be used in fabricating the implant materials, scaffolds and bone grafting. In current study, the finite element modeling is performed to evaluate the mechanical properties and structural behavior of bone at nano scale and cohesive element with different mechanical properties is applied. After its verification, the stress distribution and elastic properties are compared with analytical Shear- Lag model. Limited studies are available on strain ratio in previous research and it is presented for different cohesive elements in current study. The influence of mineral volume fraction and mechanical properties of collagen is investigated. The comparison between FE models and the other ones demonstrate an excellent agreement. The collagen- HA interface with unknown mechanical properties is the most important parameter in mineralized collagen fibril and by analyzing different parameters in current research, the thick layer of water with Van der Waals interaction and Viscous shear is determined as the most probable cohesive layer. The result of parametric studies indicates the significant effect of non linear collagen on the model behavior. In order to decrease the cost of investigation in 3D models, the proposed unit cell with periodic boundary conditions could be employed.