夹心式纵弯复合模式压电陶瓷超声换能器的研究

对夹心式纵弯复合压电陶瓷超声换能器进行了理论及实验研究，该换能器由金属细棒及纵向极化的压电陶瓷圆环组成。得出了换能器中纵向振动和弯曲振动的共振频率方程。通过修正金属细棒的长度和横截面积，实现了换能器中纵向振动与弯曲振动的同频共振。实验结果表明，换能器的测试频率与计算频率基本符合，而且换能器的纵向频率和弯曲振动频率也吻合。     

夹心式压电陶瓷功率超声换能器的优化设计

对夹心式压电陶瓷功率超声换能器的优化设计进行了探讨，分析了一种压电陶瓷中间带有厚电极的夹心式换能器的频率特性及其机电转换性能，得出了金属厚电极的几何尺寸对换能器振动性能的影响，探讨了换能器中压电陶瓷片的位置和几何尺寸对换能器的共振频率、反共振频率和有效机电耦合系效的影响，并得出了一些有利于夹心式换能器优化设计的结论。     

弯曲振动压电陶瓷换能器

介绍了一种夹心式弯曲振动压电陶瓷换能器，该换能器由压电陶瓷半圆片、前后金属盖板以及预应力螺栓三部分组成，在结构上类似于夹心式纵向振动换能器。从弯曲振动细棒的运动方程出发，得出了夹心式弯曲振动压电换能器的频率设计方程，在此基础上，进行了弯曲振动换能器设计，结果表明，利用本文得出的公式设计换能器，其共振频串的测试值与设计值基本符合。     

夹心式压电超声扭转振动换能器的设计

对夹心式压电超声扭转振动换能器进行了研究，得出了其共振频率方程，给出了切向极化压电陶瓷剪切波的等效声速。对于扭转振动换能器系统设计理论的建立提供了一定的理论基础。     

一种新型的径向振动高频压电陶瓷复合超声换能器

 本文研究了一种新型的径向振动压电陶瓷高频复合超声换能器.该换能器由一个压电陶瓷圆环和一个嵌于其内部的金属圆盘复合而成.首先对压电陶瓷圆环及金属圆盘的径向振动进行了简单分析,推出了其机电等效电路和共振频率方程,分析了压电陶瓷圆环的几何尺寸对其共振及反共振频率的影响.在此基础上,分析了由压电陶瓷圆环和金属圆盘组成的复合换能器的径向振动,得出了其复合机电等效电路和共振频率方程.研究分析表明,对于具有相同外半径的压电陶瓷圆盘和压电陶瓷圆环,压电陶瓷圆盘的径向振动共振频率高于压电陶瓷圆环的径向共振频率,并且,压电陶瓷圆环的内半径越大,其径向共振频率越低.当在压电陶瓷圆环内部嵌入一金属圆盘而组成一径向复合超声换能器时,其径向共振频率高于压电陶瓷圆盘的径向共振频率,从而达到了提高换能器共振频率的目的.研制了一些径向复合高频超声换能器,并对其共振频率进行了测试,测试数据证明了理论结果的正确性.     

利用激光干涉技术研究压电换能器的谐振特性

介绍了压电超声换能器的基本结构及振动模态，利用先进的激光多普勒干涉仪对自制换能器的谐振特性以及振动速度和位移分布进行了测量和分析，并与有限元分析的结果进行了对比，实验表明，实验测量模态结果与有限元分析结果基本相符，激光多普干涉技术是一种直观研究压电超声换能器振动的有效手段。通过有限元分析和先进测量手段的结合与对比，对换能器的设计和制作具有指导意义。     

双激励源压电陶瓷超声换能器的共振频率特性分析

 本文对具有两组压电陶瓷激励元件的夹心式功率超声压电换能器进行了理论及实验研究.当换能器中的两组压电陶瓷元件分别被激励时,换能器可以产生两组不同的共振及反共振频率.利用换能器的梅森等效电路,得出了其频率方程.探讨了换能器的共振频率及反共振频率与其几何尺寸及电学边界条件的依赖关系.研究表明,换能器的共振频率不仅与其几何形状和尺寸有关,而且与电学边界条件有关.在同样的几何尺寸下,电端开路时的共振及反共振频率大于电端短路时的共振及反共振频率.在两种电学边界条件下,换能器的共振及反共振频率与几何尺寸之间的依赖关系是相似的,即当换能器圆锥前盖板的半径比增大时,换能器的共振及反共振频率总是降低的.     

一种新型扭转振动压电陶瓷超声换能器

研究了一种新型扭转压电陶瓷超声换能器.基于机电类比原理,对切向极化的压电陶瓷薄圆环振子的扭转振动特性进行了研究,建立了其机电类比等效电路模型,从等效电路得出了环形振子的扭转振动频率方程的解析式及共振频率的计算公式.在此基础上,分析了换能器的共振与其几何尺寸间的关系;并利用有限元方法对压电陶瓷薄圆环扭转振动模态进行了分析.结果表明,在换能器压电陶瓷圆环内外半径比增大时,共振频率随之增大.     

糖类抗原CA125水平测定在结核性腹膜炎诊治中的意义

研究了一种新型扭转压电陶瓷超声换能器.基于机电类比原理,对切向极化的压电陶瓷薄圆环振子的扭转振动特性进行了研究,建立了其机电类比等效电路模型,从等效电路得出了环形振子的扭转振动频率方程的解析式及共振频率的计算公式.在此基础上,分析了换能器的共振与其几何尺寸间的关系;并利用有限元方法对压电陶瓷薄圆环扭转振动模态进行了分析.结果表明,在换能器压电陶瓷圆环内外半径比增大时,共振频率随之增大.     

超声轴承用压电换能器结构设计与有限元分析

提出了一种超声轴承用新型径向挤压式压电换能器,对换能器的机电特性进行了有限元分析。明确了有限元建模方法,从模态分析角度分析压电换能器的谐振频率和径向最大振幅,依据模态分析结果对压电换能器的幅频特性进行谐响应分析,采用正交试验法对换能器结构进行优化设计,制作最佳结构压电换能器样机,并进行工作频率测试。实验结果表明,换能器径向振动谐振频率的有限元计算值与实验结果具有良好的一致性,证明了有限元计算的正确性,为超声轴承用压电换能器的设计研究提供重要价值。     

Characteristics of Microwave Acoustic Transducers for Volume Wave Excitation

Transducers which utilize acoustoelectric conversion in a piezoelectric film, plate, or surface have found wide application for generating planar volume-acoustic waves at microwave frequencies. A review is given of the electrical impedance, conversion loss, and bandwidth characteristics for piezoelectric film or plate transducers which vibrate in one-dimensional thickness extensional or shear modes. The transducer response is related to the electric and acoustic parameters that describe the transducer configuration, and experimental examples are given to illustrate the operation of typical transducer configurations. Methods for achieving low conversion loss and/or broad bandwidth are discussed and experimental examples given. Tables of bulk material constants are supplied for commonly used plate and film devices, and transducer fabrication methods are reviewed. Other types of volume wave transducers, such as those utilizing a single piezoelectric surface, a diffusion layer in a piezoelectric semiconductor, or mode conversion at a boundary are also briefly discussed.     

基于压电传感器的单一模态Lamb波损伤检测

基于压电传感器的板类结构兰姆(Lamb)波损伤检测,提出了一种利用单一模态Lamb波的无基准损伤检测方法,并在铝板上进行损伤检测实验。根据压电传感器的理论模型,实验中选取单一模态Lamb波检测频率,并从含损伤板的检测信号中准确识别出损伤反射回波信号,根据损伤反射回波传播时间及对应的理论群速度,计算了损伤与传感器的距离。针对理论群速度和实际群速度差异对距离计算造成的误差,提出了一种改进的计算方法,将误差降低到3%以下。结果表明,利用单一模态Lamb波可识别结构中的损伤散射信号,并可有效计算损伤与传感器的距离。     

An I-shape linear piezoelectric actuator using resonant type longitudinal vibration transducers

Resonant type longitudinal vibration transducers are used in this work to construct a linear piezoelectric actuator with four driving feet. Totally three longitudinal transducers are integrated in I-shape to form the proposed actuator, which contains one vertical transducer and two horizontal transducers. These three transducers vibrate under longitudinal modes with certain temporal sequence, whose vibrations are superimposed in the actuator to generate elliptical motions on the four driving feet. The three transducers are tuned to be suitable dimensions, under which they have very close 1st longitudinal resonance frequencies; the working frequency of the piezoelectric actuator is designed to be about 31.3 kHz. The vibration coupling problem between the longitudinal transducers are studied by calculating the motion trajectories of the four feet. It is found that the temporal shift of the longitudinal vibrations can be used to tune the movement trajectories; the four feet can get nearly the same vertical displacements under a phase shift of 105°. At last, the vibration characteristics and mechanical output performances of a prototype are measured. The working frequency of the prototype, the maximum speed, and the maximum thrust force are measured to be 33.15 kHz, 1563 mm/s, and 158.2 N, respectively.     

压电超声换能器的电端匹配电路及其分析

本文分析了压电超声换能器的几种匹配电路及其匹配原理,推出了超声频电发生器与换能器之间的理想匹配条件,研究了电端匹配电路对换能器的谐振频率及其有效机电耦合系数的影响,所得结论为压电超声换能器匹配电路的设计提供了一定的理论依据。     

体波声光器件中换能器特征频率的测定

在体波声光器件换能器设计中,往往把它的厚度共振频率f_o作为工作频率。本文通过对换能器的几个特征频率的分析与测定,指出工作频率应选取在它的机械串联共振频率f_3上,并提出了从史密斯圆图上的换能器阻抗与频率的关系曲线上找出f_3的方法。     

A metal-insulator-piezoelectric semiconductor electromechanical transducer

A deposited metal-insulator-piezoelectric-semiconductor (MIPS) transistor can be used as an electromechanical transducer, because of the sensitivity of the power-gain mechanism in a surface field-effect device to fixed charge in the channel. Close correspondence has been obtained between the theory of this effect and experimental observations on deposited CdS MIPS devices. The transducer action described in this paper is quite different from that employed in other piezoelectric pressure transducers, and has beneficial characteristics such as high sensitivity and flat gain to high frequencies. Comparisons with conventional transducers are made, and design considerations of the MIPS transducer are discussed.     

Pyroelectric imaging of defects in bulk acoustic wave lithium niobate transducers

Initial results on a method for testing piezoelectric transducers made of a polar material are presented. The method consists of measuring the voltage induced across the transducer electrodes by an intensity-modulated laser beam scanning the surface. Applied to a bulk acoustic wave LiNbO3 transducer, this technique has revealed domains with Z-axis reversed.