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Critical Stresses for Extension of Filament‐Bridged Matrix Cracks in Ceramic‐Matrix Composites: An Assessment with a Model Composite with Tailored Interfaces
Author(s) -
Danchaivijit Sawai,
Shetty Dinesh K.,
Eldridge Jeffrey
Publication year - 1995
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.1151-2916.1995.tb08460.x
Subject(s) - materials science , composite material , composite number , residual stress , shrinkage , ceramic , toughness , cracking , bridging (networking) , tension (geology) , epoxy , stress (linguistics) , ceramic matrix composite , fracture toughness , matrix (chemical analysis) , ultimate tensile strength , computer network , linguistics , philosophy , computer science
Matrix cracking was studied in a model unidirectional composite of SiC filaments in an epoxy‐bonded alumina matrix. The residual clamping stress on the filaments due to the shrinkage of the epoxy was moderated with the addition of the alumina filler, and the filament surface was coated with a releasing agent to produce unbonded frictional interfaces. Uniaxial tension specimens with controlled through‐cracks with bridging filaments were fabricated by a two‐step casting technique. Critical stresses for extension of the filament‐bridged cracks of various lengths were measured in uniaxial tension using a high‐sensitivity extensometer. The measured crack‐length dependence of the critical stress was in good agreement with the prediction of a stress‐intensity analysis that employed a new force‐displacement law for the bridging filaments. The analysis required independent experimental evaluation of the matrix fracture toughness, the interfacial sliding friction stress, and the residual tension in the matrix. The matrix‐cracking stress for the test specimens without the deliberately introduced cracks was significantly higher than the steady‐state cracking stress measured for the long, filament‐bridged cracks.