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Failure of Crossply Ceramic‐Matrix Composites
Author(s) -
O'Day Michael P.,
Curtin William A.
Publication year - 2002
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.1151-2916.2002.tb00311.x
Subject(s) - materials science , composite material , ultimate tensile strength , ceramic matrix composite , weibull distribution , ceramic , bridging (networking) , composite number , stress (linguistics) , flexural strength , stress concentration , fiber , weibull modulus , volume fraction , fracture (geology) , fracture mechanics , mathematics , computer network , linguistics , philosophy , computer science , statistics
The fast‐fracture and stress‐rupture of a crossply ceramic‐matrix composite with a matrix through‐crack are examined numerically to assess the importance of fiber architecture and the associated stress concentrations at the 0/90 ply interface on failure. Fiber bridging in the cracked 0 ply is modeled using a line‐spring bridging model that incorporates stochastic and time‐dependent fiber fracture. A finite‐element model is used to determine the stresses throughout the crossply in the presence of the bridged crack. For both SiC/SiC and a typical oxide/oxide, the fast‐fracture simulations show that as global failure is approached, a significant fraction of fibers near the 0/90 interface are broken, greatly reducing the stress concentration. For fibers with low Weibull moduli ( m < 10), the tensile strength is thus nearly identical to that of a unidirectional composite scaled by the appropriate fiber volume fraction, while for fibers with larger Weibull moduli ( m ≥ 10), there are modest (10−17%) reductions in tensile strength. Stress‐rupture simulations show that initially high stress concentrations are relieved as fibers fail with evolving time near the 0/90 interface and shed load away from the interface. For a wide range of fiber properties, efficient load redistribution occurs such that the crossply rupture lifetime is generally within an order of magnitude of the unidirectional lifetime, when the applied stress is normalized by the relevant fast‐fracture strength. Overall, stress concentrations at the 0/90 interface are largely relieved with increasing load or time due to the nonlinear bridging response and preferential fiber failure near the interface, resulting in crossplies that respond very similarly to unidirectional composites.