ABSTRACT
This chapter describes the energy and stress intensity approaches to linear fracture mechanics. It introduces the concept of the singularity-dominated zone and alluded to single-parameter characterization of crack tip conditions. The chapter describes the work of Griffith, who has shown that fracture requires sufficient energy to propagate a crack. It discusses the exceeding the cohesive stress at the crack tip is necessary but not sufficient to cause fracture. The chapter invokes the principle of superposition to show that any loading configuration can be represented by appropriate tractions applied directly to the crack face. It presents an updated perspective on the interrelationship between specimen dimensions, crack tip triaxiality, and fracture toughness. The chapter provides additional information on crack tunneling and the formation of shear lips. It lists the governing equations from which linear fracture mechanics is derived. The chapter focuses on two early approaches developed by Williams and Westergaard.
