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A generic model for creep rupture lifetime estimation on fibrous ceramic compositesBecause of their high strength and toughness at elevated temperatures, fiber reinforced ceramic composites such as SiC(f)/SiC and SiC(f)/Si3N4 have become candidates for next-generation turbine engine materials. A generic model is proposed for assessing the lifetime of this class of materials when subjected to long-term creep rupture conditions. This 2D model consists of interfacial cracks growing between square grains and rectangular fibers in the direction normal to the principal tensile stress axis. Neglecting transient effects, the total lifetime is derived based on the criterion that rupture is due to coalescence of adjacent cracks. Lifetime is inversely proportional to crack growth rate, volume fraction, and aspect ratio of the fibers; but extremely sensitive to the applied stress, due to the high power of the V-K(I) law. This lifetime estimation seems to be in fair agreement with the creep rupture data of SiC(w)/Si3N4 composite with 0 and 30 vol percent reinforcement tested at 1250 C in air. TEM performed on the postcrept specimens revealed that creep damage is predominantly in the form of microcracks at matrix/matrix as well as fiber/matrix interfaces, approximately in accord with the model simulation.
Document ID
19930054898
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Chuang, Tze-Jer
(NIST, Ceramics Div., Gaithersburg MD, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1992
Publication Information
Publication: In: Fracture mechanics of ceramics. Vol. 10 - Fracture fundamentals, high-temperature deformation, damage, and design; Proceedings of the 5th International Symposium, Nagoya, Japan, July 15-17, 1991 (
Publisher: Plenum Press
Subject Category
Composite Materials
Accession Number
93A38895
Funding Number(s)
CONTRACT_GRANT: NASA ORDER C-82000-R
Distribution Limits
Public
Copyright
Other

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