Large-dimension piezoelectric ceramic composite transducer with point-defect, square-lattice phononic crystal

Abstract

<p indent=0mm>To improve the longitudinal working efficiency of large-dimension sandwich piezoelectric ceramic composite transducers (PccTs), reduce the strong coupling between longitudinal and transverse vibrations, and improve the longitudinal displacement distribution uniformity of the front radiation end of the transducer, three rows and three columns of two-dimensional (2D) air cylindrical holes arranged in a square lattice parallel to the axial direction of the transducer were fabricated on the front cover plate of a large-dimension sandwich PccT. By changing the radius of the air cylindrical hole in the center of the 3×3 supercell, a point defect is introduced to construct 2D square lattice near-periodic phononic crystals based on the abnormal radius point defect. This design can use the incomplete bandgap of the crystal in the radial direction to suppress the transverse vibration of the large-dimension PccT and can use the Anderson localization characteristics of the point defect to adjust the intensity and phase of the local sound field to further improve the uniformity of the displacement distribution of the radiation surface of the front cover plate. In addition, the influence of the structural parameters of the air cylindrical hole with the point defect on the longitudinal resonance frequency and the longitudinal vibration displacement distribution is analyzed. The simulation results show that the large-dimension PccT based on point defect, phononic crystals can suppress the axial stray modal of the transducer, significantly optimize the longitudinal relative displacement distribution of the radiation surface, and improve the performance of large-dimension PccTs.