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Size‐Effect on the Fracture Toughness and the R ‐Curve of Carbon Materials
Author(s) -
Sakai Mototsugu,
Kurita Hisashi
Publication year - 1996
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1996.tb08093.x
Subject(s) - materials science , fracture mechanics , crack growth resistance curve , fracture toughness , composite material , toughness , brittleness , crystallite , fracture (geology) , carbon fibers , graphite , composite number , crack closure , metallurgy
A theoretical extension of the Bažant size‐effect law to crack propagation problems is made in order to analyze the R ‐curve‐related microfracture mechanisms of brittle materials. The specimen's size‐effect on the fracture toughness and crack growth resistance curve ( R ‐curve) is formulated in a generalized fashion without assuming the similitude restriction of test specimen geometry, being more convenient for the study of R ‐curve behavior. Using the size‐effect law proposed in this work, the dimensions of the crack‐tip process zone as well as the crack‐face bridging region are estimated in the fracture mechanics analysis of carbon materials (a polycrystalline graphite and a carbon‐matrix/ carbon‐fiber composite). Microstructural observations confirm these fracture mechanics estimates.