Available at www.elsevierMathematicscom PPLED MATHEMATICS ONPUTATION ELSEVIER Applied Mathematics and Computation 152(2004)473-48 www.elsevier.com/locatelam Fracture mechanisms for Sic fiber and SiC/Sic composites under stress-rupture conditions at high temperatures LA. DiCarlo.hm. yun j.B. hurst Materials Division, NASA Glenn Research Center, 21000 Brookpark Road, Cleveland, OH 44135 USA ture structural materials depends strongly on maximizing the fracture or rupture life of the load-bearing fiber and matrix constituents. Using high-temperature data measured under stress-rupture test conditions, this study examines in a mechanistic manner the effects of various intrinsic and extrinsic factors on the creep and fracture behavior of a variety of Sic fiber types. It is shown that although some fiber types fracture during a large primary creep stage, the fiber creep rate just prior to fracture plays a key role in determining fiber rupture time(Monkman-Grant theory) If it is assumed that Sic matrices rupture in a similar manner as fibers with the same microstructures, one can develop simple mechanistic models to analyze and optimize the stress-rupture behavior of SiC/SiC composites for applied stresses that are initially below matrix cracking. Published by elsevier Inc. Keywords: SiC fibers; SiC matrices; SiC/SiC composites; Creep: Rupture; Mechanisms; Monkman- Grant diagrams 1. Introduction For long-term structural applications under high-temperature oxidizing conditions, research efforts are ongoing throughout the world to develop Sic E-Imail address: james. a dicarlo(@nasa. gov (J.A. DiCarlo) tter Published by Elsevier Inc doi:10.10l6/S0096Fracture mechanisms for SiC fibers and SiC/SiC composites under stress-rupture conditions at high temperatures J.A. DiCarlo *, H.M. Yun, J.B. Hurst Materials Division, NASA Glenn Research Center, 21000 Brookpark Road, Cleveland, OH 44135, USA Abstract The successful application of SiC/SiC ceramic matrix composites as high-tempera￾ture structural materials depends strongly on maximizing the fracture or rupture life of the load-bearing fiber and matrix constituents. Using high-temperature data measured under stress-rupture test conditions, this study examines in a mechanistic manner the effects of various intrinsic and extrinsic factors on the creep and fracture behavior of a variety of SiC fiber types. It is shown that although some fiber types fracture during a large primary creep stage, the fiber creep rate just prior to fracture plays a key role in determining fiber rupture time (Monkman–Grant theory). If it is assumed that SiC matrices rupture in a similar manner as fibers with the same microstructures, one can develop simple mechanistic models to analyze and optimize the stress-rupture behavior of SiC/SiC composites for applied stresses that are initially below matrix cracking. Published by Elsevier Inc. Keywords: SiC fibers; SiC matrices; SiC/SiC composites; Creep; Rupture; Mechanisms; Monkman– Grant diagrams 1. Introduction For long-term structural applications under high-temperature oxidizing conditions, research efforts are ongoing throughout the world to develop SiC * Corresponding author. E-mail address: james.a.dicarlo@nasa.gov (J.A. DiCarlo). 0096-3003/$ - see front matter Published by Elsevier Inc. doi:10.1016/S0096-3003(03)00570-8 Applied Mathematics and Computation 152 (2004) 473–481 www.elsevier.com/locate/amc