There has been a trend recently to use specimen geometries for toughness measurement that are more representative of actual flaw geometries in service. A prominent example is the use of single-edge-notched tension specimens for assessment of surface flaws in pipelines. To obtain a resistance (R) curve, i.e. J-integral or CTOD as a function of crack growth, it is necessary to monitor the crack size as a function of J or CTOD. To facilitate obtaining these data from a single specimen, the elastic

more »

... CMOD unloading compliance C has been used in several testing programs to estimate crack size. C is a function of several variables in addition to crack sizenotably, specimen constraint (plane stress or plane strain). In this paper, the dependence of C on these variables will be discussed.