ASA 125th Meeting Ottawa 1993 May

1pSA7. Ultrasonic monitoring of tensile, fatigue, or creep specimens in situ.

D. Hazony

G. Welsch

Case Western Reserve Univ., Cleveland, OH 44106

G. Halford

NASA Lewis Res. Ctr., Cleveland, OH 44135

A method is proposed for monitoring tensile, fatigue, or creep specimens while the testing is in progress. Two transducers, one transmits---one receives, are imbedded in both ends of the specimen. Sharp time-limited ultrasonic pulses permeate through the specimen from either end along the principle axis. Axial and radial strains may be monitored simultaneously by selectively tracking two of the received echoes. [see D. Hazony, ``Edge effects in short pulse piezoelectric transducers,'' J. Acoust. Soc. Am. 86, 1230--1233 (1989), Sec. IV]. The method is especially useful at elevated temperatures, aggressive environments, relatively high fatigue-cycling frequencies, and a wide range of strains. Generation and growth of cracks may also be tracked and monitored. Data may be gathered from the beginning to the last few microseconds in the life of the specimen. Salient features of the tests will be discussed. Actual data, slides, and a video tape will be presented. [Work supported by TecSonics, Inc. of Twinsburg, Ohio.]