Issue 28

D. Gentile et alii, Frattura ed Integrità Strutturale, 28 (2014) 42-50; DOI: 10.3221/IGF-ESIS.28.05 49 -1 -0.5 0 0.5 1 0 0.5 1 1.5 2 2.5 3 3.5 x 10 -3 Dimensionless angle COD/2 (mm) model  50  30  50  60 Figure 11 : t = 3.4mm; crack length 2  (  0°) and (  0°). CONFIGURATION GE-EPRI[6] [mm] EXPERIMENTAL MEASURE [mm] ERROR% 2  50T2 4.9E-3 7.2E-3 32 2  90T2 1.5E-3 1.8E-3 17 2  90T3.4 2  50T5 5.4E-3 6.5E-3 14 2  50T5 1.4E-3 1.5E-3 7 Table 2 : Comparison betweenmaximumCOD calculatedbyGE-EPRI and the experimental values. C ONCLUSIONS n this work, an experimental investigation on the shape of the COD profile for off-centered circumferential crack in bended pipe was carried out. COD measures were performed on pipes with different thickness, different crack length, and for different values of the off-crack angle. These measures have been used to validate the hodograph conemethod which provided a geometrical solution for the determination of the CODmodification as a function of the pipe geometry, crack length and off-axis angle. The comparison of the HCM solution and present COD measures indicates that the HCM is very accurate and rubout tools for predicting the COD for off-centered crack configuration suggesting its use as valid alterative to extensive finite element analysis in LBB analysis. The measures of the maximum COD for the centered crack configuration were compared with GE-EPRI solutions. It was found that for the selected R/t pipe ratio and crack opening angle, the GE-EPRI provides always a maximum CTOD that is larger than that measured in the experiments. This difference, although conservative, becomes larger when considering shorter crack length and thinner pipe. R EFERENCES [1] Bonora, N., COD of off-centred cracks in pipes under bending load: A geometrical solution, International Journal of Fracture, 75(1) (1996) 1-18. [2] The Nuclear Regulators' Working Group Task Force on Leak Before Break, "European safety practices on the applicationof leak before break (LBB) concept,"No. EUR 18549EN (2000). [3] Wilkowski, G., Leak-Before-Break: What Does It Really Mean?, Journal of Pressure Vessel Technology, 122 (2000) 267-272. I