Framatome Contribution to IBECC Benchmark for Weibull Stress Calculation

Abstract Fracture tests are usually carried out for Compact Tension (CT) specimens because this type of specimens is well known to provide more severe results than other geometries, such as Single Edge Notched Bend (SENB) or Single Edge Notch Tension (SENT) specimens. This is because there is an inherent conservatism, due to the constraint effect, in the usual interpretation of the fracture tests based on stress intensity factors. This conservatism remains when toughness values issued from CT specimens are used for the justification of actual components. In order to circumvent this bias, a solution could be looked for in a Beremin model (Beremin, 1983). By taking into account constraint effects, the fast fracture calculations could evaluate more accurately the risk of fracture. This can be implemented by replacing the historical criteria based on stress intensity factor by a criterion based on the Weibull stress. Contrary to stress intensity factors which are commonly used in the industry and for which there are numerous comparisons for their calculations by different software programs, Weibull stress calculations are not yet so widely spread and benchmarked in the industry. The main objective of the IBECC benchmark is to check that the participants can obtain similar results of Weibull stress for given configurations. This article presents the contribution of Framatome to the benchmark for two configurations: a CT specimen calculation and a pure theoretical model.