Abstract:

Many advanced transducers, such as those for medical ultrasound imaging, are made of composite materials. These composites contain both piezoelectric active and inactive constituents and therefore have a nonuniform surface vibration profile. This nonuniform surface vibration will in turn influence many characteristics of the acoustic beam pattern produced by the transducer, such as the focusing ability, sidelobes, and the near-field pressure distribution. These complex transducer systems cannot be modeled properly using equivalent circuit models due to the 3-D nature of the transducer vibration. A 3-D finite-element modeling scheme will be given in this presentation. The modeling contains two stages: First, a finite-element method is used to study the nonuniform structural vibrations of the composite transducer and obtain the surface velocity and displacement distributions; second, this surface velocity and displacement information will be fed to the Helmholtz integral to derive the transducer radiation pattern. It is also possible to compute directly the near-field pressure distribution using FEM. Accurate predictions on the transducer behavior are obtained. In addition, stress and electric field concentrations inside the transducer can be calculated. Comparison with experimental results will be shown via an animation.