Abstract: The fracture toughness of hard biomaterials, such as nacre, bovine hoof wall and beetle cuticle, is associated with fibrous or lamellar structures that deflect or stop growing cracks. Their hardness and reduced modulus were measured by using a nanoindenter in this paper. Micro/nanoscale cracks were generated by nanoindentation using a Berkovich tip. Nanoindentation of nacre and bovine hoof wall resulted in pile-up around the indent. It was found that the fracture toughness (K_C) of bovine hoof wall is the maximum, the second is nacre, and the elytra cuticle of dung beetle is the least one.

Key words: bionics, biomimetics, biomaterials, nanoindentation, laminated structure, fracture toughness