ABSTRACT
Recall Figure 1.7 in Chapter 1, which illustrates the so-called fracture mechanics triangle. When designing a structure against fracture, there are three critical variables that must be considered: stress, flaw size, and toughness. Fracture mechanics provides mathematical relationships between these quantities. Figure 9.1 is an alternative representation of the three key variables of fracture mechanics. The stress and flaw size provide the
driving force
for fracture, and the fracture toughness is a measure of the material’s
resistance
to crack propagation. Fracture occurs when the driving force reaches or exceeds the material resistance. Chapter 7 and Chapter 8 describe experimental methods to measure fracture toughness in metals and nonmetals, respectively. This chapter focuses on approaches for computing the fracture driving force in structural components that contain cracks.
