The need for optimized acoustic transducers for the development of high-quality imaging probes requires efficient simulation tools providing reliable descriptions of the behavior of real devices. The purpose of this work is the implementation of a finite-element model for the simulation of periodic transducer arrays. By using the assumption of harmonic excitation, the harmonic admittance of the studied structure can be derived. It is then shown how the mutual admittance is deduced from this feature, allowing one to estimate the amount of cross-talk effects for a given periodic transducer. Computation results are reported for standard linear acoustic probes, 2-2 ͑one-dimensional periodic͒ and 1-3 ͑two-dimensional periodic͒ piezocomposite materials. In the case of 2-2 connectivity composites, a comparison between nonperiodic and periodic computations of the mutual admittance is conducted, from which the minimum number of periods for which periodic computations can be trustfully considered can be estimated.
Ultrasound transducers are widely used in acoustic imaging applications to launch and receive pressure waves radiated and diffracted in fluids or solids. The design and optimization of these devices require the development of accurate models taking into account their actual working conditions. Particularly, much of work has been devoted to simulate ultrasound transducers radiating in semi-infinite fluids. Such developments are devoted to accurately predict the frequency bandwidth of ultrasound transducers ͑optimization of their axial resolution͒ but also their sensitivity. In the proposed work, a mixed formulation combining finite element and boundary element methods has been developed to simulate acoustic radiation of piezotransducers in fluids, using a rigorous analytical development of the 2D Green's function of the fluid. Results of the proposed calculation are compared to those provided using a more classical approach previously developed based on a numerical integration using Gauss points and weights. It is shown that the proposed approach yields efficient analysis of 2D problems with a very low sensitivity to the number of boundary elements used to simulate radiation phenomena.
A procedure based on a periodic finite element analysis is proposed to optimize 2-2 composite transducers. The principle of this approach consists in reducing parasitic lamb wave propagation which may be guided by the structure by a proper choice of volume fraction of the PZT and the polymer. This information is deduced from the dispersion curve.The validity of the theoretical analysis is checked experimentally using 2 MHz 2-2 composite transducers.
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