Evaluation of toughness requirements in cracked components based on fracture-mechanics methods

Abstract Different fracture-mechanics based defect assessment procedures have been checked using results of wide-plate tests. The CTOD-Design-Curve-Approach, the CEGB-R6-routine, the EPRI-approach and methods using Finite-Element-Computations to evaluate the crack driving force lead to safe predictions of the failure behaviour of components as long as the limits of application are considered carefully. Reversing the conventional procedure of defect assessment, the CTOD-Design-Curve approach and the FEM based method can be used to derive toughness requirements. The requirements depend on the component and defect geometry, the strength of the material and the safety criterion. For practical application simple diagrams have been evaluated showing the required toughness e.g. as a function of crack length or material strength.