Analysis of spurious resonances in single and multi-element piezocomposite ultrasonic transducers

1-3 piezocomposites provide for significant advantages over solid piezoceramic transducers for ultrasound applications, at the expense of introduction of additional spurious resonances. We examine in detail the generation of high frequency inter-pillar (lateral) resonances in 1-3 piezoelectric composites, through experiment and finite element analysis (FEA) with the PZFlex package. These inter-pillar modes are clearly shown to be generated due to Lamb waves propagating through the substrate between pillars, the magnitude of which varies dependent upon magnitude of displacement from the thickness mode vibration and its proximity in the frequency domain.