Flexible ultrasonic transducers for transverse horizontal plate waves

Novel transverse horizontal (TH) guided wave transducers comprising of piezoelectric fiber composites (PFC) sandwiched between interdigital electrodes are presented and named as TH-PFC transducers. The driving electric field is applied in orientations perpendicular to the piezoelectric fibers, in which the poling direction parallels the fibers. Dispersive characteristics and frequency responses of the lowest several TH modes in PFC have been determined by a periodic finite-element method. The symmetric and anti-symmetric TH waves are induced by face shear and thickness shear mode vibrations, respectively. The TH guided waves in a PFC adhered on the surface of a host plate can be classified into two groups, PFC modes and plate modes, in accordance with the deformation that is dominated by the PFC or the host plate. Numerical and performance test results indicate that the TH-PFC transducers with anti-symmetrically aligned electrodes possess greater capacity to actuate and sense TH guided waves in structures.