夹心式功率超声压电陶瓷换能器的工程设计

文中为换能器的优化设计和性能改善提供一些有用的设计指南和解决措施,并对功率超声夹心式压电陶瓷换能器工程设计中的一些重要问题(即换能器各部分的功能及选择,压电陶瓷元件的位置优化,接触界面对换能器性能的影响与预应力的选择及影响等)进行了简要的分析。结论表明,文中所述对于优化设计、改善并提高性能具有参考和使用价值。     

指数型纵—扭复合模式超声换能器研究

纵-扭复合模式夹心式压电超声换能器是超声马达、超声加工等应用技术中的重要组成部分.本文研究的复合模式换能器由圆柱型金属后盖板、指数型金属前盖板及轴向极化和切向极化的二组压电陶瓷晶堆组成.导出了换能器中纵向振动与扭转振动模式的共振频率方程.并得出了两种振动同频共振的条件.实验表明.换能器的测试频率与设计频率符合很好.且换能器的纵向共振频率与扭转共振频率基本一致.     

扭转振动压电超声换能器的研究

本文对夹心式复合结构压电超声扭转振动换能器进行了系统的理论研究，该换能器由两段金属真圆棒及切向极化的压电陶瓷圆片堆复合而成，文中首先研究了切向极化压电陶瓷细长管的扭转振动性，推出了其机电等效电路，并提出了压电陶瓷细长管截面扭转系数的概念。，     

B7 纵-扭复合振动夹心式压电超声换能器的研究

Ｂ６扭转振动夹心式压电超声换能器的研究阎向宏，张福成（石油大学数理系山东东营·２５７０６２）夹心式压电超声换能器，以其较小的体积和重量而获得较大的声能密度和高的机械强度，在功率超声中的应用极为广泛。以前，人们的注意力主要集中于对压电纵振动超声换能器的...     

超声波料位仪的研制

超声料位仪上的换能器主要是夹心式和多波节复合弯曲换能器，本文介绍了一种采用压电陶瓷圆管径向振动模式的超声波料位仪，它的工作频率21kHz，最大量程25m，盲区≤0．85m，工作可靠性能稳定．     

一种可用于重油降粘的大功率超声换能器设计

基于夹心式压电换能器基本原理,设计了一种可用于井口重油降粘和高凝油降凝的工业规模应用的大功率压电超声换能器,其工作频率为16.86 kHz,输入电功率为500 W,可在100℃高温环境下长时间连续工作。首先根据工作环境需要设计了换能器模型,结合等效电路法和传输矩阵法,计算了换能器满足谐振频率条件的各部分参数;通过有限元仿真软件ANSYS对换能器进行了模态分析和谐响应分析,确定了换能器的最佳工作模态和工作频率。根据仿真模型,制作了工程样机,通过阻抗分析仪测得其实际的工作频率与仿真结果的误差为0.5%。这种大功率压电超声换能器有望在重油降粘以及超声处理工业中得到规模化应用。     

压电复合材料用于透镜式聚焦换能器的研究

为了增加聚焦换能器的带宽, 抑制其多模振动耦合现象, 提高电声转换效率, 实验采用1-3型压电复合材料代替压电陶瓷作为超声发射材料, 设计并制作了一种新型的1-3型压电复合材料透镜式聚焦换能器。通过频率特性的对比研究, 证明了1-3型压电复合材料透镜式聚焦换能器不仅能增加换能器的带宽, 达到PZT压电陶瓷透镜式聚焦换能器带宽的3.13倍, 而且能明显抑制径向振动, 得到单一纯净的厚度振动模态。另外, 1-3型压电复合材料透镜式聚焦换能器的电声转换效率达到PZT压电陶瓷透镜式聚焦换能器的1.88倍, 为高效率聚焦超声换能器的实现提供了理论及实验基础。     

大功率纵-弯超声振动系统的研究

本文研究了一种大功率纵－弯昨合模式超声振动系统。该系统由两个纵向大功率夹心式压电超声换能器及一个均匀截面直棒组成。文中给出了该振动系统的具体结构及其共振频率设计方程。根据均匀直棒的纵向及弯曲振动理论，导出了振动系统中纵向及弯曲振动同频共振的条件。     

复频超声换能器的研究

研究了一种具有多个共振频率的功率超声换能器，即复频超声换能器。换能器由一个纵向振动夹心式压电超声振子和一个弯曲振动薄圆盘复合而成。给出了换能器的理论共振频率方程，对实际制作的换能器的共振频率，等效电阻抗及有效机电耦合系数进行了实验测试，并对换能器的大功率工作性能进行了定性的测量及观察。实验结果表明，给出的换能器可以在不同的振动模式上工作，因此具有许多共振频率，且对应换能器不同的共振频率，换能器的等     

一种超声手术刀推挽激励换能器的研究

设计了一种超声手术刀用的新型推挽激励换能器。它是在夹心式单晶堆压电超声换能器的经典构造基础上,把原先激励一组压电陶瓷晶片堆的方式,改为同时施加反相激励的前后两组晶堆。利用有限元方法,对该推挽激励换能器进行模态分析和频率响应分析。在相同大小的电压激励下,相对单晶堆换能器,推挽激励换能器可以获得更高的工作带宽和机电耦合系数,提高了换能器的电声转换效率。按照仿真结果加工推挽激励换能器,实现良好的动力学和电学特性,满足设计要求。     

Radiation impedance and equivalent circuit for piezoelectric ultrasonic composite transducers of vibrational mode-conversion

The piezoelectric ultrasonic composite transducer, which can be used in either gas or liquid media, is studied in this paper. The composite transducer is composed of a longitudinal sandwich piezoelectric transducer, a mechanical transformer, and a metal circular plate in flexural vibration. Acoustic radiation is produced by the flexural circular plate, which is excited by the longitudinal sandwich transducer and transformer. Based on the classic flexural theory of plates, the equivalent lumped parameters for a plate in axially symmetric flexural vibration with free boundary conditions are obtained. The radiation impedance of the plate is derived and the relationship between the radiation impedance and the frequency is analyzed. The equivalent circuits for the plate in flexural vibration and the composite transducer are given. The vibrational modes and the harmonic response of the composite piezoelectric transducer are simulated by the numerical method. Based on the theoretical and numerical analysis, two composite piezoelectric ultrasonic transducers are designed and manufactured, their admittance-frequency curves are measured, and the resonance frequency is obtained. The flexural vibrational displacement distribution of the transducer is measured with a laser scanning vibrometer. It is shown that the theoretical results are in good agreement with the measured resonance frequency and the displacement distribution.     

Radial vibration of the composite ultrasonic transducer of piezoelectric and metal rings

The radial composite ultrasonic transducer of a piezoelectric ceramic ring and a metal ring is studied. The radial vibrations of a piezoelectric ceramic ring polarized in the thickness direction and a metal ring are analyzed and their electromechanical equivalent circuits are obtained. On the basis of the electromechanical equivalent circuits of the piezoelectric and the metal ring and the radial boundary conditions, the total electromechanical equivalent circuit for the composite ultrasonic transducer is also obtained. The resonance frequency and anti-resonance frequency equations of the composite ultrasonic transducer are given. Some radial composite ultrasonic transducers are designed and manufactured and their resonance and anti-resonance frequencies are measured. Experiments show that the measured resonance frequencies are in a good agreement with the theoretical results.     

Radially composite piezoelectric ceramic tubular transducer in radial vibration

The radially composite piezoelectric tubular transducer is studied. It is composed of radially poled piezoelectric and a long metal tube. The electro-mechanical equivalent circuit of the radially poled piezoelectric and metal tube in radial vibration is obtained. Based on the force and velocity boundary conditions, the six-port electro-mechanical equivalent circuit for the composite tubular transducer is given and the resonance/anti-resonance frequency equations are obtained. The relationship between the resonance frequency and the dimensions is analyzed. Numerically simulated results obtained by the finite element method are compared with those from the analytical method. Composite piezoelectric tubular transducers are designed and manufactured. The resonance/anti-resonance frequencies are measured, and it is shown that the theoretical results are in good agreement with the simulated and experimental results. It is expected that radially composite piezoelectric tubular transducers can be used as high-power ultrasonic radiators in ultrasonic applications, such as ultrasonic liquid processing.     

Analysis of piezoelectric ultrasonic transducers attached to waveguides using waveguide finite elements

A finite-element modeling procedure for computing the frequency response of piezoelectric transducers attached to infinite constant cross-section waveguides, as encountered in guided wave ultrasonic inspection, is presented. Two-dimensional waveguide finite elements are used to model the waveguide. Conventional three-dimensional finite elements are used to model the piezoelectric transducer. The harmonic forced response of the waveguide is used to obtain a dynamic stiffness matrix (complex and frequency dependent), which represents the waveguide in the transducer model. The electrical and mechanical frequency response of the transducer, attached to the waveguide, can then be computed. The forces applied to the waveguide are calculated and are used to determine the amplitude of each mode excited in the waveguide. The method is highly efficient compared to time integration of a conventional finite-element model of a length of waveguide. In addition, the method provides information about each mode that is excited in the waveguide. The method is demonstrated by modeling a sandwich piezoelectric transducer exciting a waveguide of rectangular cross section, although it could be applied to more complex situations. It is expected that the modeling method will be useful during the optimization of piezoelectric transducers for exciting specific wave propagation modes in waveguides.     

Sandwiched piezoelectric ultrasonic transducers oflongitudinal-torsional compound vibrational modes

Sandwiched piezoelectric ultrasonic transducers of longitudinal-torsional compound vibrational modes were studied. The transducers consist of coaxially segmented, longitudinally and tangentially polarized piezoelectric ceramic rings, a back metal cylinder, and a front exponential solid metal horn. Based on the plane-wave approximation, the equivalent circuits of the longitudinal and torsional vibrations in the sandwiched transducer were obtained and the resonance frequency equations of the transducer in longitudinal and torsional vibrations were derived. By means of choosing the radius decay coefficient of the front exponential horn, the longitudinal and torsional vibrations are made to resonate at the same frequency in the transducer. Sandwiched piezoelectric ultrasonic transducers of longitudinal-torsional compound modes were designed and fabricated according to the frequency equations. It is demonstrated that the measured resonance frequencies of the transducers are in good agreement with the theoretical results, and the measured resonance frequencies of the transducers in longitudinal and torsional vibration modes are also in good agreement with each other. Theoretical and experimental results show that this kind of transducer can be used in ultrasonic welding, ultrasonic machining, ultrasonic motors, and other ultrasonic applications which need large displacement amplitudes     

Study on a new type of radial composite piezoelectric ultrasonic transducers in radial vibration

In this paper, a new type of radial composite ultrasonic transducers in radial vibration is presented and studied. The radial composite ultrasonic transducer consists of a solid piezoelectric ceramic thin disk and a hollow metal thin, circular ring in radial vibration; and they are connected together in the radial direction. The radial vibrations of a piezoelectric ceramic thin disk and a hollow, metal, thin, circular ring are analyzed, respectively. Their radial electromechanical equivalent circuits are obtained. Based on the electromechanical equivalent circuits and using the boundary conditions between the piezoelectric ceramic thin disk and the hollow, metal, thin ring, the electromechanical equivalent circuit of the radial composite ultrasonic transducer is derived and the resonance frequency equation is obtained. The theoretical results from the resonance frequency equation are in good agreement with the measured radial resonance frequencies, and they also are in a good agreement with the results from the numerical method.     

A high sensitivity hydrostatic piezoelectric transducer based ontransverse piezoelectric mode honeycomb ceramic composites

A new piezoelectric composite transducer based on the ceramic honeycomb structure is introduced. The transducer is operated in the transverse piezoelectric (TP) d₃₁ mode. The ceramic honeycomb configuration enables one to fabricate a TP honeycomb transducer by either embedding a honeycomb ceramic skeleton into a soft polymer matrix to form a composite or by blocking the openings of the honeycomb cells with thin layers of epoxy to form an end-capped honeycomb structure. With the unique honeycomb configuration and TP operation mode, the piezoelectric d₃₃ response of the ceramic is nearly eliminated and the piezoelectric responses from the three orthogonal directions add together when the transducer is subjected to a hydrostatic pressure. As a result, the transducer exhibits exceptionally high hydrostatic piezoelectric response