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Simulation of Composite Fatigue Resulting from Chemical Attack of Bridging Fibers
Dennis N. Coon
Ajit S. Motkur
Department of Mechanical Engineering
University of Wyoming
Laramie, WY 82072
A numerical simulation that predicted fatigue-like behavior resulting from chemical attack of bridging fibers in a cracked composite was developed. Chemical attack of bridging fibers led to mechanical failure of bridging fibers, and a corresponding reduction in the closure stress. As the closure stress decreased, the crack grew to form new bridging fibers. Crack growth rates were predicted to increase linearly with increased applied stress, and a fatigue exponent of 0.62 ± 0.06 was predicted. The predicted fatigue exponent was approximately an order of magnitude less than fatigue exponents reported for SiC/SiC composites in the literature. The low predicted fatigue exponent may indicate that mechanisms other than chemical attack of bridging fibers are operable in high-temperature experiments reported in the literature.