ABSTRACT
This chapter discusses the basic concept of why and how the hierarchical architecture with functionally graded properties exists in Mother Nature's creations, especially in natural composites such as bone, teeth, scale, shell, hair, and so on. It discusses the importance of structure-property correlation. The chapter describes the basics of mechanical properties measurement at the scale of microstructure. It then explores how nanoindentation with combined finite element method can be used as a powerful and useful technique to determine plastic properties of small volume sample. The toughness component of the bone comes from the fiber and organic phase, while the hardness component arises from minerals and HAp crystals. The interpretation of the mechanical behavior of teeth, a nano-bio-composite with different structural levels, shall need to be performed in correlation to its structural and compositional characteristics. The detail structures of hair are extensively studied by several researchers by electron microscopy techniques.
