13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- Table 3. Experimentally observed angles compared with numerical values ρ [mm] β [°] θ0, FEM [°] θ0, EXP. [°] ρ [mm] β [°] θ0, FEM [°] θ0, EXP. [°] 0.25 30 37.1 36.5 0.25 60 67.3 64.3 0.5 30 32.7 32.1 0.5 60 63.3 60.1 1 30 30.9 36.1 1 60 61.6 63.7 2 30 30.0 33.6 2 60 61.6 64.0 4 30 30.0 31.2 4 60 60.0 58.0 0.25 45 52.5 50.3 0.5 45 50.0 54.9 1 45 47.5 49.6 2 45 46.2 49.1 4 45 45.0 48.5 5. Conclusions The SED criterion was extended to rounded-tip notched domains in order to estimate the fracture load of notched graphite components. It was shown that the proposed method is suitable for the isostatic graphite stressed under mixed mode loading conditions, being the experimental results in good agreement with the results estimated by the SED approach. From the sound agreement between the theoretical and experimental results, it can be directly deduced that for the isostatic graphite the critical energy and the radius of the control volume are both constant material properties and independent of the loading mode, and can be simply evaluated from a pure mode I test. References [1] H. Awaji, S. Sato Combined mode fracture toughness measurement by the disc test. J. Eng. Mater. Technol., 100 (1978) 175-2. [2] Y. Yamauchi, M. Nakano, K. Kishida, T. Okabe. Measurement of fracture toughness for brittle materials under mixed mode impact loading using center-notched disk specimen. Zairyo /J. Soc. Mater. Sci. Japan, 49(12) (2000) 1324-9. [3] Y. Yamauchi, M. Nakano, K. Kishida, T. Okabe Measurement of mixed-mode fracture toughness for brittle materials using edge-notched half-disk specimen. Zairyo /J. Soc. Mater. Sci. Japan, 50(3) (2001) 229- 4. [4] M. Li, M. Tsujimura, M. Sakai Crack-face grain interlocking/bridging of a polycrystalline graphite: The role in mixed mode fracture. Carbon, 37(10) (1999) 1633-9. [5] L Shi, L Haiyan, Z Zhenmin, ASL Fok, BJ Marsden, A Hodgkins, PM. Mummery, J. Marrow. Analysis of crack propagation in nuclear graphite using three-point bending of sandwiched specimens. J. Nucl. Mater., 372 (2008) 141-51.
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