Modeling of piezoceramic composite transducer structures generating strong sound pulses in therapy

In order to simulate composite piezoelectric structures, which are applied in self-focusing transducers for therapy, a 3-D modeling approach is presented here. Assuming a plane and infinite transducer, a finite element model can be obtained using symmetry conditions. The realistic electrical drive by high voltage pulses was also included in the simulation. Transient FEM-analysis of transducer designs with a single layer of piezoelectric ceramics and stacked layers including water loads show good agreement to measured pressure pulses. The interaction of single elements expresses in a constructive superposition of their radiated pulses at relatively large distances of a few centimeters forming a nearly plane wave front. Variations of some geometric parameters of the composite structure show the ability to influence the pulse amplitude and shape.