and

The program to be described here was initiated during the past year at the Air Force Materials Laboratory. The problem of deterMining adhesive bond strength was undertaken with a rather brute-force approach of simply collecting the best possi-ble data, utilizing existing ultrasonic plane-wave theory for layed structures to calculate ultrasonic spectra, and then attempting the inversion of the d~ta to obtain the acoustic properties of the mate-rlal or structure. An empirical correlation of these acoustic properties with the destructively measured bond strength is planned. This research was initiated to determine whether in general, continuous-wave ultrasonic techniques ' would provide more accurate data than conventiona