点缺陷正方晶格声子晶体的大尺寸压电陶瓷复合换能器

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

为了保证大尺寸夹心式压电陶瓷复合换能器的纵向工作效率,减少纵、横振动之间的强烈耦合,改善换能器前辐射端面的纵向位移分布均匀度,本文在大尺寸夹心式压电陶瓷复合换能器的前盖板上,加工了3行3列与换能器轴向平行的按正方晶格排列的二维空气圆柱孔,并通过改变3×3超元胞中心空气圆柱孔的半径来引入点缺陷,构造基于半径异常型点缺陷的二维正方晶格近周期声子晶体.该设计不仅可以利用晶体在径向的不完全带隙对大尺寸压电陶瓷复合换能器的横向振动进行抑制;还可以利用点缺陷的Anderson局域化特性,调控局域声场的强度和相位,进一步改善前盖板辐射面的位移分布均匀度;另外,本文分析了点缺陷空气圆柱孔的结构参数对换能器纵向共振频率以及纵向振动位移分布的影响规律.仿真结果表明,基于点缺陷声子晶体的大尺寸压电陶瓷复合换能器能够有效抑制换能器轴向的杂散模态、大幅优化辐射面纵向位移分布,改善大尺寸压电陶瓷复合换能器的性能.

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 largedimension PccTs.