STP761: Fracture Tolerance Analysis of the Solid Rocket Booster Servo-Actuator for the Space Shuttle

    Smith, SH
    Principal Research Scientist, Principal Research Scientist, and Research Scientist, Battelle Columbus Laboratories, Columbus, Ohio

    Ghadiali, ND
    Principal Research Scientist, Principal Research Scientist, and Research Scientist, Battelle Columbus Laboratories, Columbus, Ohio

    Zahoor, A
    Principal Research Scientist, Principal Research Scientist, and Research Scientist, Battelle Columbus Laboratories, Columbus, Ohio

    Wilson, MR
    Senior Design Engineer, Moog Incorporated, East Aurora, N.Y.

    Pages: 30    Published: Jan 1982


    Abstract

    The results of an evaluation of the fracture tolerance of three components of the thrust vector control servo-actuator for the solid rocket booster of the space shuttle are described. These components were considered as being potentially fracture critical and therefore having the potential to fall short of a desired service life of 80 missions (that is, a service life factor of 4.0 on a basic service life of 20 missions). Detailed stress analysis of the rod end, cylinder, and feedback link components was accomplished by three-dimensional finite-element stress analysis methods. A dynamic structural model of the feedback system was used to determine the dynamic inertia loads and reactions to apply to the finite-element model of the feedback link. Twenty mission stress spectra consisting of lift-off, boost, re-entry, and water impact mission segments were developed for each component based on dynamic loadings. Experimental fracture response data da/dN, KIc, and Kc were used for the structural alloys of the actuator components. These alloys were Inconel 718, 17-4 PH (H1025), 6061-T651, 2024-T851 (T351), and A286. Linear fatigue crack growth life and residual strength analyses were performed on the component critical locations using the Forman da/dN equation and CRACKS III computer code. Most components were determined to have the potential of reaching a service life of 80 missions or service life factor of 4.0.

    Keywords:

    stress analysis, fracture mechanics, stress intensity factors, mission spectra, dynamic loads, finite element models, fatigue crack growth life, residual strength, service life factor


    Paper ID: STP28872S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP28872S


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