Ultrasonic Characterization of Aluminum Matrix Composite Elasticity: Experiment and Theory.
Progress rept. Oct 77-Aug 78,
NAVAL SURFACE WEAPONS CENTER WHITE OAK LAB SILVER SPRING MD
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The ability to make meaningful elastic moduli measurements ultrasonically is reported for potential application to the nondestructive evaluation of aluminum matrix composites. The materials were monitored for a change in elasticity as a function of heat treatment that would affect the materials residual stress state. We evaluate initial results obtained on two unidirectional UD systems 1 continuous graphite Gr fiber reinforced Al, and 2 discontinuous SiC whisker reinforced Al. The requisite five elastic moduli C sub ij for a UD system were obtained by measuring bulk acoustic velocities, first in the as-fabricated material. The engineering constants, e.g., longitudinal and transverse Youngs moduli, were in good agreement with available tensile test data. The samples were then subjected to single cycle liquid nitrogen and elevated temperature excursions, and the elastic moduli remeasured at room temperature. Results indicate a significant effect on the residual stress state specifically, a reduction in modulus of GrAl, but no effect on SiCAl. Author
- Laminates and Composite Materials
- Metallurgy and Metallography