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    Structural Synthesis of Composite Materials for Ablative Nozzle Extensions

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    Complexities associated with the application of composite materials for the thermal protection of aerospace structures are discussed in the light of a detailed investigation of the Titan III Stage II ablative nozzle extension. This paper describes the methods used in a structural evaluation of the nozzle extension that led to an understanding of several structural failures. Results of an experimental investigation of the composite material properties and analyses of the nozzle extension's response to mechanical and thermal loads are presented. Particular attention is focused on the challenges encountered in testing to obtain the properties of the liner and shell materials over their operating temperature ranges. The importance of individual material properties and fabrication variables is explored. The effect of moisture content on thermal expansion and stress levels is shown to be of primary importance. Also, the ability to vary stress levels by changing the tape wrap angle is demonstrated. The experience gained from this investigation is translated into a structural synthesis approach tailored to the specific requirements of current aerospace programs. The importance of integrating the various interacting technical disciplines in terms of the design configuration, environmental conditions, material thermal and mechanical properties, thermal and structural analyses, fabrication techniques, and process controls is discussed. Finally, conclusions drawn from the nozzle extension study are extended to other applications of composite materials.


    ablative materials, rocket nozzles, composite materials, structural design, mechanical properties, stress analysis, fabrication, structural compatibility, evaluation, tests

    Author Information:

    Au, N. N.
    Associate head, Aerospace Corp.,

    Scheyhing, E. R.
    Member of Technical Staff, Aerospace Corp.,

    Summers, G. D.
    Member of Technical Staff, Aerospace Corp.,

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP49834S