Flexible ultrasonic transducers using piezoelectric fiber composites with antisymmetric interdigital electrodes

A conformal ultrasonic transducer constructed by piezoelectric fiber composites (PFC) with new arrangement of electrodes is numerically and experimentally studied. This device is designed to transmit and receive guided waves of constant wavelength for structural health monitoring application. A periodic finite element approach has been used to demonstrate the electric field induced by symmetric or anti-symmetric electrodes as well as working principle of this device interacted with the host plate. The extensional mode of this device is used to actuate both A₀ and S₀ modes of Lamb waves in the host plate. The added mass effect of PFC has more notable influence on transmission of S₀ modes than A₀ mode in the area near both edges of PFC. The linear scan of transmitted acoustic waveforms along the axis in front of the transducer by a laser Doppler vibrometer reveals the near-field interference pattern, which is caused by the guided waves of constant wavelength.