Experiences in the Use of Guided Ul Trasonic W a Ves to Scan Structures

The use of gmded ultrasonic waves to rap1dly mterrogate !arge structures is a topic that 1s currently receiving considerable attention. The purpose of this paper, and the companion paper by Alers [I], is to briefly review some past expenence that may not be readily available to current researchers since many of the results were not presented in archival publications. The work described in this paperwas conducted in the context of explonng apphcations of electromagnetic-acoustic transducers (EMATs) [2,3] as apart of the NDE effort at the RockweH International Sc1ence Center m the period 1970-1980. In addition to the author, others playing key roles in vanous parts of th1s effort included G. A. Alers, R. K. Elsley, C. M. Fortunko, M.W. Mahoney and C. F. Vasile. The compamon paper by Alers mcludes subsequent developments at the private company, Magnasonics, Inc. as well as more recent work at the National Institute of Standardsand Technology. Although EMA T's were used in all of this work as the sensors to excite and detect the guided uhrasonie modes, the bas1c 1deas apply to the use of gmded modes excited by any kind of sensor to scan structures.