Numerical analysis of mineral crystals on mechanical properties of mineralized collagen fibers

Bone, with excellent mechanical properties, can adapt to a variety of external forces through adjust its complex hierarchical structure. The basis of the hierarchical structure is mineralized collagen fibers, which consist of mineral crystals and collagen fibers. To better understand the mechanical properties of mineralized collagen fibers, we establish a series of representative volume element models of mineralized collagen fibers based on the different arrangement of mineral crystals in the collagen fibers. The effects of crystal aspect ratio, volume fraction, and crystal defect on the effective elastic modulus and Poisson's ratio of mineralized collagen fibers are calculated by combining the homogenization theory with the finite element method. Results show that the elastic modulus of mineralized collagen fibers can be regulated effectively by adjusting the aspect ratio and volume fraction of crystals. This research explains the mechanical advantages of mineralized collagen fibers in the structure, provides a basis for the calculation of high level structure of bone and offers insight into the design of bionic composite materials.