Schedule

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1975
Wednesday, January 1st
12:00 AM

Acoustic Surface Wave Generation with Electromagnetic Transducers

Robert Thomas, Wayne State University

Thousand Oaks, CA

12:00 AM

In the program description Don Thompson mentioned that one of the overall objectives was to try to increase the communication between the basic research community and the NDE user, and I'd like to mention that my own involvement in NDE did not come from a specific problem oriented research project in NDE. In fact , my interest in electromagnetic generation began from some physics problems, particularly with studies of the electronic properties of potassium single crystals at liquid helium temperature where the contactless feature of electromagnetic transducers was a useful advantage.

Development of a Field Inspection System for Detection of Cracks Under Installed Fasteners

W Woodmansee, Boeing

Thousand Oaks, CA

12:00 AM

The work that I'm going to describe was funded by the Air Force Materials Lab from February 1972 to February 1974. It is described in an AFML report, TR- 74-80, available from the Air Force. This report describes a more practical type of problem than has been discussed so far. Our work was directed towards building an ultrasonic system to be used on aircraft in the field to detect cracks around fastener holes with the fastener in place. With this system we are able to detect cracks and locate them relative to the depth of the hole. Estimates of crack size by this method are not very accurate.

Narrow Band Gap Semiconductors as Acoustic Phonon Transducers

A H. Francis, University of Illinois at Chicago

Thousand Oaks, CA

12:00 AM

It 's actually with some considerable apprehension that I address this audience. I will try to alleviate my apprehension somewhat by telling you right at the outset that I do not have a single data slide showing a detected flaw. What's more I have to confess, I have never detected a flaw. I sincerely hope you'll forgive me for this. My apprehension is heightened by my observation over the last several days that there is very little interest in ultrasonic work at the frequencies that are of interest to me, the range of about 1 to 10 GHz. I don't think I've heard anything over 1 GHz mentioned. Perhaps it's becoming apparent to most of you that I am not principally in nondestructive evaluation. What I am interested in is lattice dynamics; more specifically relaxation effects in dielectric solids.

Optimization and Application of Electrodynamic Ultrasonic Wave Transducers

Bruce Maxfield, Cornell University

Thousand Oaks, CA

12:00 AM

First, let me describe briefly what I have in mind when I talk about electrodynamic ultrasonic wave transducers. There are a number of transducers which I would put in this class including the capacitive microphonetype transducers, which are based on an electrodynamic phenomenon as opposed to piezoelectric phenomena. However, I am going to focus my attention on a particular type of electrodynamic device, the electromagnetic acoustic wave transducer or EMAT for short. I will describe electromagnetic acoustic wave generation and, hopefully, will show you how transducers based on this phenomenon have been understood in rather great detail. It is then up to all of us to try and apply this information to solve NDE problems. With this background information, I hope that you will feed back to me ideas so that we can work together on applications.

Piezoelectric Transducers for Quantitative NDE

Ken Lakin, University of Southern California

Thousand Oaks, CA

12:00 AM

Piezoelectric transducers are undoubtedly one of the major elements for use in ultrasonic NDE. and our program essentially was involved for the last nine months in what you might call the NDE of NDE transducers, sort of NDE. Hopefully, we're not multiplying two small numbers together here. So, what I'd like to do is just give a summary of what we have been doing and tell you how far up on the learning curve we are.

Transducers Applied to Measurements of Velocity Dispersion of Acoustic Surface Waves

Harold M. Frost, United States Air Force
Thomas L. Szabo, United State Air Force

Thousand Oaks, CA

12:00 AM

This talk concerns two new acoustic surface wave (SAW) transducer units developed and applied to the field of nondestructive testing. We confine ourselves here to tone burst transduction of Rayleigh waves (at MHz frequencies), although CW operation and (for example) Lamb and bulk waves are also possible.