Pratt & Whitney Aircraft and NASA Lewis Research Center studied a silicon-carbide-fiber-reinforced, titanium-metal-matrix (MMC) composite designated SiC(SCS-6)/Ti-15V-3Cr-3Al-3Sn. Fracture tests of three nominal 15.24-cm (6-in.) diameter SCS–6/Ti-15-3 rings at 427 °C (800 °F) and room temperature resulted in failure at internal pressures of 0.172 GPa (25 ksi) (average) and 0.235 GPa (34.1 ksi), respectively. Predictions of internal pressure to failure varied from 0.140 to 0.276 GPa (20.3 to 40.1 ksi) at 427 °C (800 °F). Nondestructive evaluation revealed that the rings’ MMC cores had varying density and were not uniformly distributed inside the monolithic casing. Analytical predictions of ring cyclic life at 0.154-GPa (22.4-ksi) internal pressure varied from 1000 to 15 000 cycles. No fatigue life data were obtained with the MMC rings for comparison with theory.

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