Ultrasonic Characterization of Aluminum Matrix Composite Elasticity: Experiment and Theory.
Abstract
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 material's 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 Young's 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 Gr/Al, but no effect on SiC/Al. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1978
- Accession Number
- ADA065138
Entities
People
- G. V. Blessing
- J. V. Foltz
- W. L. Elban
Organizations
- Naval Ordnance Laboratory