NONSTEADY-STATE THERMAL STRESS BEHAVIOR OF REFRACTORY MATERIALS.
Technical rept. Mar 66-Oct 67,
TRW SYSTEMS GROUP REDONDO BEACH CA
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The thermal and deformation histories of hollow cylindrical specimens were measured during exposure to high heat fluxes produced by electron bombardment of the inside surfaces of the specimens. Transient thermal environments comparable in severity to those produced by rocket engine exhaust and re-entry heating were considered. Using the measured thermal history as input to a thermal stress analysis stresses and strains throughout the specimen were calculated. Plasticity and anisotropy are taken into account in the analysis. Good correlation was obtained for values of measured and calculated circumferential strains for the outside diameter of the specimens. Results were obtained for AXF-5Q, AXF-9Q, PO-3 and ATJ graphite and recrystallized extruded tungsten. High temperature mechanical properties were measured in using special test apparatus and procedures which were developed to meet the requirements of the thermal stress analysis. Results for tungsten at temperatures up to 5500 F and for strain rates of 0.1 to 10 in.in.min. were presented. A parametric study was conducted to obtain a better understanding of the thermomechanical behavior of cylindrical bodies subjected to large transient temperature and pressure loadings. The parameters were evaluated in terms of the influence they exert on the stresses and strains induced at the inner and outer surfaces of the cylinder. Author
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