NASA’s turbine seal facility tests air-to-air seals for advanced jet engines. High temperature, speed, and pressure combinations limit test disk life, due to crack initiation in the Grainex Mar-M 247 disk bolt holes. An inspection interval is determined to ensure safe operation. Fatigue strain-life data is presented for test specimens from a test disk. Strain-life models (Manson-Hirschberg method of universal slopes, Halford-Nachtigall mean stress method, and modified Morrow method) were compared to experiment. Using experimental data at −99.95% prediction levels, accounting for six bolt holes at 0.5% total strain and 649°C, the test disk should be inspected after 665 cycles.
Issue Section:Gas Turbines: Manufacturing, Materials & Metallurgy
Keywords:jet engines, materials testing, aerospace test facilities, aerospace safety, life testing, crack detection, aerospace materials, fatigue cracks, discs (structures)
Topics:Cycles, Disks, Fatigue, Fracture (Materials), Stress, Test facilities, Turbines
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