Finite element modeling of piezoelectric transducers including internal losses

Abstract

An actual radiating sonar transducer is always generating heat, due to internal losses and to the friction between the different parts of the structure. Thus its efficiency is lower than 1 and a temperature rise can occur. To describe these phenomena, the finite element code ATILA [Decarpigny et al., J. Acoust. Soc. Am. 78, 1499 (1985)] has been improved by including the effects of internal losses, using a complex Young's modulus for isotropic materials and complex tensors for piezoelectric ceramics. Then, electrical and thermal measurements have been performed on various sandwich transducers, at different drive levels, to determine the ceramics loss angles. Finally, the electrical impedance, transmitting voltage response, and mechanical displacement field have been computed for a multifrequency Tonpilz transducer [Boucher et al., J. Acoust. Soc. Am. Suppl. 1 80, S27 (1986)] and a ring transducer [Bossut et al., J. Acoust. Soc. Am. Suppl. 1 74, S23 (1983)] radiating in water, and the theoretical results have been compared to experimental values, showing a reasonable agreement which will be carefully discussed.