ABSTRACT
This chapter introduces some of the concepts including the important property of toughness. It provides to predict and analyse fracture and considers predictions of strength from knowledge of the bonding forces between atoms. The chapter explores the theoretical basis for some of the observed deformation behaviour along the way. There are both attractive and repulsive forces between atoms, which balance one another when the atoms are in equilibrium. Atoms at the surface are bonded to other surface atoms and atoms further into the material; they therefore have asymmetric bonding forces leading to a higher energy state than that of atoms within the material, which have uniform bonding in all directions. The atoms will be torn apart near the crack tip, but the crack will only grow through the material if there is also sufficient energy in the system to keep driving it.
