It has been shown both experimentally {2} and theoretically {2,3} that surface skimming SH waves propagating along symmetry axes of the texture have velocities that differ in proportion to the magnitude of any stress that lies along one of the symmetry axes. Specifically, the stress is directly proportional to the relative velocity difference through the equation -,--V ik=---V. -=ki) ( I) cr. = 2G (-V ~ ik where cr. is the stress in the direction i, G is the shear modulus and Vik is the ~elocity of an SH wave propagating in the i direction and polarized in the k direction. This rather simple relationship is particularly useful because the constant of proportionality involves only the well known shear modulus and the velocity term can be measured directly by observing the transit time shift when a transmitter-receiver pair of SH wave transducers are rotated through 90 degrees on the surface of the part. Experimentally, Equation (I) was tested on the web of railroad rails which had been loaded by a 200,000 pound mechanical testing machine {I}. The method of exciting and detecting the necessary surface skimming SH waves used electromagnetic acoustic transducers (EMATs) that operated through a magnetostrictive mechanism at high magnetic fields {4}. Wave velocities parallel and perpendicular to the axis of the rail on the web differed by the amount predicted by Equation (I) to an absolute accuracy of 30 percent in the worst case.

These Proceedings, consisting of Parts A and B, contain the edited versions of most of the papers presented at the annual Review of Progress in Quantitative Nondestructive Evaluation held at the University of Washington, Seattle on July 30 to August 4, 1995. The Review was organized by the Center for NDE at Iowa State University, in cooperation with the Ames Laboratory of the USDOE, the American Society of Nondestructive Testing, the Department of Energy, the National Institute of Standards and Technology, the Federal Aviation Administration, the National Science Foundation IndustryiUniversity Cooperative Research Centers, and the Working Group in Quantitative NDE. This year's Review of Progress in QNDE was attended by approximately 450 participants from the US and many foreign countries who presented over 375 papers. The meeting was divided into 36 sessions with as many as four sessions running concurrently. The Review covered all phases of NDE research and development from fundamental investigations to engineering applications or inspection systems, and it included many important methods of inspection science from acoustics to x-rays. In the last several years, the Review has stabilized at about its current size. Most participants seem to agree it is large enough to permit a full-scale overview of the latest developments but still small enough to retain the collegial atmosphere which has marked the Review since its inception. The Proceedings are structured in a format to reflect the organization of the Review itself, producing a more logical organization for both the meeting and the present volume.

It has been shown both experimentally {2} and theoretically {2,3} that surface skimming SH waves propagating along symmetry axes of the texture have velocities that differ in proportion to the magnitude of any stress that lies along one of the symmetry axes. Specifically, the stress is directly proportional to the relative velocity difference through the equation -,--V ik=---V. -=ki) ( I) cr. = 2G (-V ~ ik where cr. is the stress in the direction i, G is the shear modulus and Vik is the ~elocity of an SH wave propagating in the i direction and polarized in the k direction. This rather simple relationship is particularly useful because the constant of proportionality involves only the well known shear modulus and the velocity term can be measured directly by observing the transit time shift when a transmitter-receiver pair of SH wave transducers are rotated through 90 degrees on the surface of the part. Experimentally, Equation (I) was tested on the web of railroad rails which had been loaded by a 200,000 pound mechanical testing machine {I}. The method of exciting and detecting the necessary surface skimming SH waves used electromagnetic acoustic transducers (EMATs) that operated through a magnetostrictive mechanism at high magnetic fields {4}. Wave velocities parallel and perpendicular to the axis of the rail on the web differed by the amount predicted by Equation (I) to an absolute accuracy of 30 percent in the worst case.