雪花形二维耦合振动夹心式压电超声换能器的设计

Design of a snowflake-shaped two-dimensional coupled vibration sandwich piezoelectric ultrasonic tranducer

为了实现单个换能器的多方向超声辐射,提出了一种新型的雪花形二维耦合振动夹心式压电超声换能器,它由正六棱柱形金属块、6组压电陶瓷晶堆和6个金属盖板组成。基于耦合振动理论和力电类比原理建立了换能器等效电路模型,推导了其共振与反共振频率方程。通过等效电路法、有限元法和试验研究了换能器的二维耦合振动特性。结果表明:当压电陶瓷晶堆越靠近正六棱柱形金属块时,换能器的有效机电偶合系数越高;随着换能器轴向尺寸的增加纵向耦合共振频率降低;在纵向耦合共振模式下,换能器的6个输出端均可输出一致的纵向位移振幅;等效电路法、有限元仿真和试验测试取得了较为一致的结果。该研究结果为该类换能器的工程应用提供了简明设计理论,研究成果有望应用于多维超声加工、多向超声辐射等领域。

In order to realize the multi-directional ultrasonic radiation for a single transducer,a new type of snowflake-shaped two-dimensional coupled vibration sandwich piezoelectric ultrasonic transducer was proposed,which consists of a hexagonal prismatic metal block,six groups of piezoelectric ceramic crystal stacks,and six metal cover plates.Based on the coupled vibration theory and the principle of electromechanical analogy,the equivalent circuit model of the transducer was established,and the resonance and anti-resonance frequency equations were derived.The two-dimensional coupled vibration characteristics of the transducer were studied by an equivalent circuit method,a finite element method and experiments.Results show that the effective electromechanical coupling coefficient of the transducer is higher when the piezoelectric ceramic stack is closer to the hexagonal prism central metal block.The longitudinal coupling resonance frequency decreases with the axial size of the transducer.In the longitudinal coupling resonance mode,the six output ends of the transducer can output consistent longitudinal displacement amplitude.The equivalent circuit method,finite element simulation and experimental test have achieved relatively consistent results.The results of this paper provide a concise design theory for engineering applications of this kind of transducer.The results are expected to be applied to multi-dimensional ultrasonic machining,multi-directional ultrasonic radiation and other fields.