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1975
Wednesday, January 1st
12:00 AM

Analysis of Ultrasonic Scattering from Simply Shaped Objects

E Richard Cohen, Rockwell International

Thousand Oaks, CA

12:00 AM

The simple shapes referred to in my title are actually restricted to spheres and spheroids , that is ellipsoids of revolution. Actually , I will not even say too much about the spheroids except to t he extent that I will concentrate on the sphere as the limiting case and as the jumping-off point for the complete analysis of the spheroid.

Basic Theory of Ultrasonic Scattering by Defects: Numerical Studies and Features for Experimental Application

J A. Krumhansl, Cornell University

Thousand Oaks, CA

12:00 AM

Well, the theory of scattering of elastic waves is difficult. I don't want to minimize that, but I thought I might make a few diversionary introductory remarks. My first reference will be the Los Angeles Times of today, the astrology column. It advises those born under the sign of Leo to choose their words carefully to avoid trouble. That happens to be applicable to yours truly. I hope I do it.

Guided and Leaking Interface Waves for NDI/NDE

David A. Lee, Air Force Institute of Technology
Dennis M. Corbly, United States Air Force

Thousand Oaks, CA

12:00 AM

Last year at this review one of us pointed out that it was theoretically possible to propagate guided elastic waves along the interface between an installed interference-fit fastener and the parts that it joins, and that these waves might be useful for nondestructive inspection and evaluationl. During discussion of that paper, the speaker was asked if experiments were planned, and another questioner wanted to know what would happen if elastic parameters of fastener and part didn't fall in the comparatively narrow ranges for which unattenuated guided waves can propagate.

The speaker replied that experiments were indeed planned, and that, hopefully, even when material parameters did not allow guided waves, attenuated interface waves might still propagate and be useful for inspection and evaluation.

This report can be viewed as an amplified answer to the two questions. We have carried out experiments. They confirm the existence of both true guided waves, and of "leaking" or attenuated waves, on interfaces between materials of engineering interest. The theory presented last year, with some extensions, is a useful guide to excitation and reception methods, propagation speeds, and for leaking modes, attenuation factors. Preliminary pulse-echo observations indicate that these waves can be used for indications of flaws in awkward places, such as on a fastener hole in an inner plate.

Quantitative Ultrasonics—Overview

R Bruce Thompson, Rockwell International

Thousand Oaks, CA

12:00 AM

I would like to give an overview of our work in quantitative ultrasonics in the ARPA/AFML program. The goal is to use ultrasonics to determine failure related or fracture critical properties of a flaw. In practice , this implies the use of ultrasonics to determine the geometric shape of the flaw: its size, its shape and its orientation with respect to a stress field.