David J. Powell
Dept. of Ocean Eng., Florida Atlantic Univ., Boca Raton, FL 33431
Robert Y. Ting
Naval Undersea Warfare Ctr., Orlando, FL 32856-8337
Thomas R. Howarth
Naval Res. Labs., Washington, DC 20375
Multilayered transducer structures offer the potential for greater performance in terms of increased radiated acoustic power and improved reception characteristics. In earlier work, a unidimensional modeling approach was presented, that was shown to provide a means of accurately predicting the in-air electrical impedance characteristics of a range of different laminated transducer structures [J. Acoust. Soc. Am. 97, 3299(A) (1995)]. These prototype devices have since been encapsulated within polyurethane rubber ready for in-water acoustic testing. This paper presents a theoretical and experimental analysis of both the transmission and reception performance characteristics of this group of multilayered devices. The effects of intermediate bondlines and electrode layers will be considered in terms of changes to both the device's sensitivity and its resonant frequency. Transducer performance will be assessed via the standard figures of merit, TVR and FFVS, in conjunction with its pulse-echo transient response. Theoretical predictions from the unidimensional model are in good agreement with experimentally obtained values. The polyurethane encapsulant was found to have detrimental effects on overall transducer performance. Beam profiles for the laminated devices have been recorded experimentally and are compared to the responses of their single-layer counterparts. [Work sponsored by the Office of Naval Research.]