13th International Conference on Fracture June 16–21, 2013, Beijing, China -9- Figure 6. Crack Driving Force curve for theoretical uniaxial cruciform specimen indicated by the red curve (A508 material at -85°C) The fracture toughness (Jc indicated by the intersection of the MFC and CDF) of the uniaxial cruciform specimen is estimated to be around 92 N/mm, while the fracture toughness of the biaxial cruciform is approximately 75 N/mm. In addition, the 3PB specimen has a slightly deeper crack than the cruciform specimens, therefore its fracture toughness is much less. The uniaxial specimen shows slightly greater loss of constraint (higher fracture toughness) when compared to biaxial specimens. This agrees with findings published by AREVA [20] related to RPV integrity assessment. 5. Conclusion The two parameter J-A2 method has been applied to experimental data obtained from testing A508B 3PB, C(T), and small scale cruciform specimens. The J-A2 method shows great potential for use to predict failure in structural components and also to quantify the constraint effect due to varying loading and geometry. However, additional work is necessary to continue examination of the method. The current study utilized a small amount of data available from the literature. Future work will involve searching for larger available fracture toughness results necessary to conduct further evaluation of the J-A2 method. References [1] ASTM, Standard E399-08, Linear-Elastic Plane-Strain Fracture Toughness KIc of Metallic Materials. Annual Book of ASTM Standards, ASTM International. [2] ASTM, Standard E1921-11, Standard Test Method for Determination of Reference Temperature, To, for Ferritic Steels in the Transition Range. Annual Book of ASTM Standards, ASTM International. [3] Hutchinson, J.W., 1968. Singular Behavior at the End of a Tensile Crack Tip in a Hardening Material. J. Mech. Phys. Solids 16 (1): 13-31.
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