Research on Nondestructive Testing.
Annual rept. 1 Sep 80-31 Aug 81,
STANFORD UNIV CA EDWARD L GINZTON LAB OF PHYSICS
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Our aim has been to develop more rapid methods of NDE, as well as quantitative techniques for determining the parameters such as stress and microstructure associated with different types of materials, in particular steels. The imaging work has made a great deal of progress. The digital imaging system is now working well. We have used a number of different modes of propagation to make quantitative observations of cracks. We have developed special-purpose transducer arrays, for instance, a contacting shear wave array, a contacting longitudinal wave array, and array systems suitable for pitchcatch operation. New collocation theoretical techniques have been developed for determining the stress field around a crack in a semi-infinite half-space. These have proven extremely useful to the rest of our program as an input on which to check experiments and other theoretical techniques. They are also of fundamental importance to the theory of scattering of acoustic waves from cracks. We have used attenuation techniques, velocity measurement techniques with bulk waves and surface waves for determining near-surface microstructure, and we have developed new theoretical methods for this purpose. Energy integrals associated with a crack have been measured by acousto-elastic techniques, and we are trying to develop further methods using shear waves to obtain more experimental information on the various types of energy integrals.
- Test Facilities, Equipment and Methods