IN CHAPTER 3, VARIOUS fracture test methods for determining the fracture toughness under conditions of slow, intermediate, and dynamic loading rates were described. Generally, fracture toughness values are referred to as Kc, the critical stress intensity factor. For specific situations, there are specific Kc values, such as KIc, for slow-loading under plane strain conditions as defined by ASTM E 399. The fracture toughness under intermediate-load rate conditions is referred to as KIc (t), where the time to maximum load is given in the parentheses. The dynamic crack arrest fracture toughness is KIa, and the critical plane-strain stress-intensity factor under conditions of impact loading is referred to as KId. Furthermore, the KIc, KIc (t), and KIa tests are frequently conducted at various temperatures to determine the “static,” “intermediate,” and “dynamic” fracture toughness of various structural materials as a function of temperature.