CRACK DRIVING FORCE CALCULATION IN ARBITRARILY SHAPED DEFECTS BASED ON 3D NON-DESTRUCTIVE EVALUATION AND FINITE ELEMENT ANALYSIS

The actual shape of a real defect differs from the simplified shapes that are assumed within an engineering critical assessment. Additionally, the re-characterization of interacting defects into one simplified defect is known to introduce conservatism, which may be undesirably large. Ongoing and expected technological advances of 3D NDE techniques (such as full-matrix capture ultrasonics and X-ray CT) allow to assume that defect simplification will no longer be required in the future, thus bypassing the uncontrolled conservatism resulting from defect simplification. A recently finished EPRG project has shown the feasibility of integrating the information provided by 3D NDE systems into finite element models. Promising results are obtained which, with additional effort, will provide a solid basis for in-the-field application. This paper first reports on the overall procedure of defect assessment by the adopted finite element analysis (both linear-elastic and elastic-plastic). Next, the ability to couple FE model construction with non-destructive evaluation results is demonstrated for three scans obtained from different sources (one X-ray CT and two ultrasonic full matrix capture scans). Finally, concrete opportunities to improve the robustness, speed and accuracy of the methodology are addressed, which will be tackled in a follow- up project funded within PRCI.