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Conference Article: Application of ISRM testing methods to fracture toughness testing of graphite

Hashida, T.; Fukasawa, T.; Takahashi, H. (Tohoku Univ., Sendai (Japan)); Ishiyama, S.; Oku, T

Abstract

Fracture toughness measurements of nuclear grade graphites, IG11 and PGX, were made by means of AE technique. Tests were conducted on edge-notched round bend bar, edge-notched short bar and round compact tension specimens. These round-shaped specimens used in this study have been proposed for standard fracture toughness tests of rock as a draft of testing standard of International Society for Rock Mechanics (ISRM). Taking the observed nonlinear deformation behavior into account, J-integral approach was utilized to determine the fracture toughness of the graphites. It is shown that the critical J integral determined by AE technique, JiAE, is independent of specimen geometry. Based on this experimental results, the fracture toughness KIC of the graphites was determined from the JiAE values. KIC value of IG11 was 1.04 MPasq rootm, and 0.77 MPasq rootm for PGX respectively. Furthermore, the specimen size effect of the fracture toughness determined by the J-integral/AE method is discussed.

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key words: acoustic emission testing; cracks; deformation; fracture properties; graphite; htgr type reactors; acoustic testing; carbon; gas cooled reactors; graphite moderated reactors; materials testing; mechanical properties; nondestructive testing; testing
Reference:
Specialists' meeting on graphite component structural design, JAERI Tokai (Japan), September 8-11, 1986
International Atomic Energy Agency, Vienna (Austria). International Working Group on Gas-Cooled Reactors
IWGGCR--11, pp:159-162