Thermal Stress Behavior of Polycrystalline Graphite. Part I.
TRW SYSTEMS GROUP REDONDO BEACH CALIF
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A program to study the thermomechanical response of polycrystalline graphite in a transient, high-heat-flux environment is described. The purpose of the investigation is to provide the basic engineering data needed for the design of advanced graphite reentry nose tips and rocket engine components. Thermal stress tests are performed in which hollow cylindrical specimens of ATJ-S and AXF-5Q graphite are heated rapidly from the inner surface. Temperature and strain measurements provide the data by which the results of these experiments are interpreted. The program also includes a series of material property tests to complement these thermal stress tests and to answer specific questions related to the behavior of graphite in a thermal stress environment. The results obtained in thermal stress on six AXF-5Q and seven ATJ-S specimens are presented. Comparisons are made between the measured and calculated strains at the specimen OD and between the calculated stresses and strains at failure and the corresponding ultimate strength and strain-to-failure in uniaxial tension. The phenomenon of stress reversal cracking in AXF-5Q graphite is also discussed. Author
- Ceramics, Refractories and Glass
- Guided Missiles
- Rocket Engines