Analysis of a radiating thin-shell sonar transducer using the finite-element method

Abstract

The design of efficient low-frequency f/extensional sonar transducers is a present challenge which is made difficult by a partial lack of general accurate mathematical models. Thus the application of the finite-element method to this problem is a promising approach which has been worked recently. To test the ability of the finite-element code ATILA [Decarpigny et al., J. Acoust. Soc. Am. 78, 1499-1507 (1985) ] to predict the in-air and in-water dynamic behavior of such structures, an axisymmetrical thin-shell transducer was built, and its acoustical behavior was experimentally and numerically analyzed. This paper first presents the modal analysis of this projector, using different finite-element meshes as well as a mixed finiteelement-plane-wave model and the comparison of numerical displacement field values to holographic measurements. Second, it describes an in-water harmonic analysis in which the model of the infinite fluid domain is reduced to a portion of the acoustic nearfield, limited by a spherical boundary upon which special damping finite elements are attached. All farfield quantities are then calculated using an efficient extrapolation algorithm [R. Bossut and J. N. Decarpigny, J. Acoust. Soc. Am. 86, 1234-1244 (1989) ]. Finally, measured transmittifig voltage response and directivity patterns are compared to the finite-element predicted values. The comparison proves the ability of the finite-element approach of provide detailed and accurate insights in the behavior of transducers working with shell vibrations.

Finite-element analysis of the nonlinear propagation of high-intensity acoustic waves

“…In particular, the finite-element method ͑FEM͒ has been widely used to model three-dimensional elastic or piezo-electric radiating structures. [12][13][14] Other numerical methods such as the boundary-element method ͑BEM͒, 15 alone or in combination with FEM ͑BEM-FEM͒, have also proved to be very powerful for linear radiation modeling. 16 The interest of extending these tools for realistic three-dimensional modeling of the nonlinear field is evident.…”

A Peep into Underwater Acoustic Transducer Analysis

“…GILMAN et al [1] were the first to use acoustic waves to probe the thermal structure of the lower atmosphere. Mc-Allister [2] later demonstrated the practical application of the technique, a work which was subsequently followed all over the world.…”

“…For electric field driven transducers, the impedance analogy is commonly used where forcejvoltage and velocity/current are analogous. For magnetic field driven transducers, the mobility analogy is more convenient where force/current and velocity/voltage are analogous [1]. …”

“…IMPEDANCE TRANSFORMATION [1] A combination of a piezoelectric material and a metal Paper No. 52-B; Copyright© 1992 by JETE. plate can be used as a sandwich transducer.…”

Acoustic field calculation for a compact barrel-stave flextensional transducer array

“…The resonant frequency, surface vibration displacement and vibration velocity distribution of the transducers can be calculated. The admittance curves, frequency response and radiation directivity curves can all be obtained [3][4][5][6]. When the surface vibration velocity distribution of the transducer has been obtained, the boundary element method can be used to calculate the radiation characteristics of the transducer and array [7][8][9][10].…”