Crack-tip opening displacement (CTOD)

This chapter presents a description of the crack-tip opening displacement (CTOD) as an alternative measure of the fracture toughness in the presence of plasticity. In addition to its definition and relationship to the plastic-zone size, a description is given on how it can be experimentally measured as a basis of a criterion for the onset of fracture. We also define how the CTOD is directly related to the J-integral. Finally, CTOD-based crack-resistance curves are described specifically for the definition of the crack-tip opening angle, which represents a seldom used measure of the crack growth toughness.