Micromechanics of bone modeled as a composite material

In this chapter, we present an overview of modeling of bone as a composite material. First, we describe bone’s complex hierarchical structure spanning from the nanoscale to macroscale and summarize bone’s mechanical properties and biological characteristics which include self-healing, adaptation, and regeneration. Then, we summarize nanomechanics and micromechanics modeling of bone. Effective medium theories such as Mori-Tanaka, self-consistent, and generalized self-consistent methods are used to model the elastic response of bone, while a finite element method is used to more precisely account for bone architecture and to simulate inelastic effects. Challenges in bone modeling include bone’s composite and hierarchical structure, lack of scale separations, scale and size effects, interfaces, porosity spanning across structural scales, and complex constitutive laws (anisotropic, nonlinear, Cosserat, time dependent, piezoelectric, poroelastic). Variability in bone properties due to the anatomic location, species, age, gender, and method of storage makes validation of theoretical models challenging. Finally, lessons learned from nature on bone structure-property relations can be applied to design stiff, strong, tough, and lightweight bioinspired materials.