Finite-difference modeling of piezoelectric composite transducers

The mechanical and electrical properties of transducers are modeled by fini te-difference representations of the relevant physical equations, and the n umerical problems are discussed. The theory is applied to (a) a ceramic tra nsducer of dimensions 1 cmx1 cmx200 mu m, (b) a polymer P of the same dimen sions, and (c) a 1-3 composite transducer consisting of transverse rods of ceramic embedded in a matrix of polymer. The results for the ceramic agree with the one-dimensional model, viz.:voltage of order 4-5 mu V and no reson ance below 10 MHz. For the polymer, the resonant frequency of 3.9 MHz is cl ose to the 4 MHz predicted by the one-dimensional theory. For the composite , introduction of the ceramic has an immediate effect on s(11), s(12) and s (13), whereas it has little effect on d(31) unless the density of the ceram ic in the mix is 30% or higher. (C) 2000 American Institute of Physics. [S0 021-8979(00)07401-6].