径向极化压电圆管超声换能器的数值模拟

Numerical Simulation of Radially Polarized Piezoelectric Cylindrical Tube Ultrasonic Transducers

应用多物理场耦合分析软件COMSOL Multiphysics对径向极化压电圆管超声换能器进行了有限元数值模拟.首先,对压电圆管的前三阶振动模态以及一阶谐振频率与圆管尺寸、激励电压的变化关系进行了模拟分析.然后,对径向极化压电圆管在无介质和介质分别为空气、水时的导纳曲线进行了模拟分析,并且模拟了压电圆管在空气和水中的超声场分布.仿真结果表明,压电圆管的一阶谐振频率与圆管尺寸存在特定的变化关系,与激励电压的大小无关;压电圆管在空气和水中的导纳曲线由于空气和水的特性阻抗不同而不同,空气对压电圆管的影响几乎可以忽略,而水对压电圆管的影响较大.最后,利用精密阻抗分析仪对所制作的径向极化压电圆管超声换能器的导纳曲线进行了测试,并与数值模拟结果进行对比.结果表明,实验测试结果和数值模拟结果基本吻合,验证了数值模拟的可靠性,可为径向极化压电圆管超声换能器的设计提供指导.

The finite element simulation of radially polarized piezoelectric cylindrical tube ultrasonic transducers has been conducted with COMSOL Multiphysics. Firstly,the first three vibration modals and the relationships between the first-order resonant frequency and tube size and the change of excitation voltage were analyzed. Then,the admittance of radially polarized piezoelectric cylindrical tube in the situations of lacking media and with the media of air and water were simulated. And the ultrasonic fields produced by piezoelectric cylindrical tube in air and in water were simulated. The simulation results show that the first-order resonance frequency changes with the size of cylindrical tube,but not with the excitation voltage. The admittance of piezoelectric cylindrical tube in air and water are varied with the change of the characteristic impedance of air and water. The influence of air on piezoelectric cylindrical tube can be ignored while water has a greater influence. Finally,The admittance of made radially polarized piezoelectric cylindrical tube ultrasonic transducer was measured by Precision Impedance Analyzer. And the measurement admittance was compared with the numerical simulation result. It is shown that the experimental result is in good agreement with the simulated result. So the numerical simulation result is reliable and can provide guidance for design of the radially polarized piezoelectric cylindrical tube ultrasonic transducers.