Foundations of fracture mechanics

This chapter provides a brief description of the origins of fracture mechanics and the methodology that preceded it. It describes the estimation of the ideal (theoretical) fracture strength to separate two planes of atoms, which is known to overestimate the experimentally measured cohesive strength of materials by more than an order of magnitude, before providing simple derivations of the Griffith and Orowan approaches which attempted to develop more realistic estimates of the stress to cause fracture. Finally, a brief description is given on how these approaches led to the creation of the discipline of fracture mechanics to provide a basis for the quantitative prediction for the onset of fracture.