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Conference Article: A statistical fracture criterion for graphite

Cords, H.; Kleist, G.; Zimmermann, R. (Kernforschungsanlage Juelich G.m.b.H. (Germany, F.R.))

Abstract

The measured mechanical strength of brittle materials shows considerable scatter due to inhomogeneities inherent in the submicroscopic and microscopic structure. Not only is the strength of graphite statistically distributed, other bulk quantities, e.g. Young's modulus and density which may be correlated to the strength, show also a scatter in measurement data, thus indicating that large scale inhomogeneities are present. Application of the statistical theory means essentially that a system is divided into subsystems which are assumed to be statistically independent of each other. The probability function of the total system is the product of probability distributions of the subsystems, the typical size of which is a cube of DELTAV=1 cm3 for a graphite with a maximum grain size of 1 mm.

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key words: brittleness; fracture properties; graphite; microstructure; statistics; stress analysis; tensile properties; carbon; crystal structure; mechanical properties
Reference:
Specialists meeting on mechanical behaviour of graphite for HTRs, Gif-sur-Yvette, France, 11-13 June 1979.
International Atomic Energy Agency, Vienna (Austria). International Working Group on High-Temperature Reactors.
IWGHTR--3, pp:110-115