ABSTRACT
Two possible routes for applying fracture mechanics theory to design can be seen: express J or COD or other desired terms as a function of the uncracked body behaviour; express J or COD or other as a function of the stress-strain behaviour and such aspects of the cracked body behaviour as may be necessary. The former clearly follows the conventional route of structural engineering, itself usually restricted to linear analysis, perhaps supplemented by a fully plastic limit load estimate, in which stress-strain data other than yield and tensile strength are often unknown. Computational fracture studies follow the latter route. It is necessary to know the stress-strain relationships, but the result can notionally be indexed to either uncracked or cracked body behaviour as the datum. LEFM is clearly indexed to the uncracked body through the 'remote' stress
0" with the cracked state entering only through the shape factor Y. The COD and En] methods outlined in this chapter are expressed predominantly in terms of the uncracked state and shape factor Yor the a to ii relationship in Ref. 10. The R-6 method explicitly involves use of cracked body limit analysis as well as the shape factor Y; the EPRI method comes near to expressing itself through cracked body data only and despite its inclusion of a wide variety of non-linear stress-strain laws, does not offer uncracked body reference analyses for most of the configurations examined, other than the linear case.
