变宽度分割电极片状压电致动器的位移特性

针对硬磁盘驱动器中磁头定位两级伺服系统设计了一种新型压电致动器——悬臂梁式变宽度分割电极片状压电致动器.沿厚度方向极化的PZT压电陶瓷薄长片，宽度沿长度方向变化且沿长轴对称，一端固定一端自由构成悬臂梁.其上下两表面的电极均沿长轴分割成对称的两部分.施加电场使其中一半在d₃₁模式作用下伸长，而与其对称的另一半缩短，则压电片沿宽度方向产生弯曲，自由端便可产生致动位移.对该致动器的驱动电压-端部致动位移特性进行了理论分析、有限元模拟及实验验证.致动器中的电场诱导应力远小于陶瓷的抗张强度.致动器端部位移的测试结果略大于理论计算值.与现有磁头悬浮臂尺寸相近的致动器，在20—50V的电压驱动下均可获得1—2μm的致动位移.对25kTPI(track per inch)的高道密度硬磁盘，该位移已能覆盖至少一个磁道宽度，满足磁头定位两级伺服系统对第二级致动器致动位移的基本要求. 关键词：     

Finite element analysis of piezoelectric actuator with PMN–PT single crystals for nanopositioning

A piezoelectric bending actuator has been used widely in areas related to precision position controlling, loudspeakers, and pressure sensing. In this paper, a fine focusing actuator is designed using a computer aided design tools, Solid Works 2004, for an optical disk drive pick-up system. The finite element analyses are performed with the software COSMOS Work 2004 and the ANSYS 5.7. The tip displacement of the piezoelectric bending actuator with PMN-PT single crystals is 46 μm at 10 V. It is 15 times larger than tip displacement of PZT ceramics for the same design. The tip displacement obtained from the finite element analyses agrees with the measured data very well.     

Nonlinearity in inverse and transverse piezoelectric properties of Pb(Zr0.52Ti0.48)O3 film actuators under AC and DC applied voltages

The motion of domain walls is a crucial factor in piezoelectric properties and is usually related to the irreversible and hysteretic behaviors. Herein, we report on the investigation of inverse and transverse piezoelectric coefficients of capacitor-based and microcantilever-based Pb(Zr_0.52Ti_0.48)O₃ films with a change in the DC bias and the AC applied voltage. A large inverse piezoelectric strain coefficient of about 350 p.m./V, and a low strain hysteresis of about 7.1%, are achieved in the film capacitors under a low applied voltage of 2 V (20 kV/cm) which can benefit the actuators for motion control in high-precision systems. The field-dependences of the transverse piezoelectric coefficients, obtained from four-point bending and microcantilever displacement, are in good agreement with each other. The results also reveal that the irreversible domain-wall motion is attributed to the nonlinearity in the field-dependent piezoelectric strain and cantilever displacement.     

A disk-pivot structure micro piezoelectric actuator using vibration mode B11

Micro piezoelectric actuator using vibration mode B(11) (B(mn), where m is the number of nodal circles, n is the nodal diameters) is designed. Different from conventional wobble-type ultrasonic motor using piezoelectric rod or cylinder, piezoelectric disc is used to excite wobble modes and metal cylinder stator is used to amplify the transverse displacement, metal rod rotor is actuated to rotate. The outer diameter of the actuator is 14mm. There are features such as low drive voltage, micromation, and convenient control of wobble state by modifying the structure of stator, etc. Finite element analysis (FEA) of the stator has been made. It is found that the resonant frequency of vibration mode B(11) is 49.03kHz, which is measured at 45.7kHz by the laser vibrometer and impedance analyzer. The rotation speed has been measured, which could be as high as 10,071rpm under an alternating current 100V. Such piezoelectric actuator can be optimized and adjusted to fit practical conditions. It can be applied in the fields of precise instrument, bioengineering and other micro actuator system.     

Magnetoelectric effect from the direct coupling of the Lorentz force from a brass ring with transverse piezoelectricity in a lead zirconate titanate (PZT) disk

A novel composite of brass ring and PZT disk shows a high dc magnetic field (H_dc) response when using the product effect of the Lorentz force effect from a metal ring in a dc magnetic field applied with ac electrical current, and the piezoelectric effect of piezoelectric material. The output voltage between the two faces of PZT shows a good linear response to the dc magnetic field (<1 kOe) under different ac electrical current inputs (<300 mA). The magnetoelectric coefficient is about ∼33.2 mV/T A. Simultaneously, the magnitude of its magnetoelectric coefficient can be manually controlled by an applied electrical current. This composite has the potential for applications in magnetoelectric transducers and sensors that work without coils even for static magnetic fields. PACS 85.80.Jm; 77.84.-S; 75.80.+q; 77.84.Dy; 77.65.-j     

钹型换能器的优化设计*

本文研究的钹型换能器,是由一个压电陶瓷圆环和一个金属浅球壳组成。为了得到这种钹型换能器的解析解和它在不同介质中的机电性能。首先,根据前人得出的压电陶瓷圆环和金属浅球壳的理论模型,用等效电路法从理论上计算出了该换能器的共振频率并与仿真结果做了对比,发现二者近似吻合,验证了理论计算的可靠性,为这种钹型换能器的优化设计提供了理论指导。然后利用COMSOL Multiphysics分别模拟了压电陶瓷为圆盘和圆环的钹型换能器的共振频率,仿真结果表明：同等条件下,当圆环的外径和圆盘的半径相等时,压电陶瓷为圆环的钹型换能器共振频率更低,使其具有频率低、体积小的特点更加明显。利用数值方法,分析了钹型换能器的几何尺寸对其共振频率、反共振频率及有效机电耦合系数的影响。最后模拟了钹型换能器在水中的机电特性及声压分布。     

A miniature class V flextensional cymbal transducer with directional beam patterns: the double-driver

The "double-driver" cymbal, a directional class V flextensional transducer, is described in this paper. Its basic structure is a bilaminar piezoelectric disk with metal caps as mechanical transformers and amplifiers. The directivity was accomplished by exciting the double-driver in a combined flexural and bending mode causing the sound pressure to add in one direction and cancel in the opposite direction. The cardioid beam pattern predicted by finite element modeling agreed well with the experimental measurements. A 3 x 3 double-driver array was constructed to demonstrate that under optimal conditions the array can provide a directional beam pattern with a front-to-back ratio of more than 20 dB.     

Design and construction of shaft-driving type piezoceramic ultrasonic motor

A new approach in design of shaft-driving type piezoceramic ultrasonic motor is proposed. The stator of motor consisted of a commercial available buzzer disk in which a piezoceramic membrane is adhered to a metal sheet. The wave propagation on the metal sheet was generated by extended-shrunk force from piezoceramic oscillation. Driving energy came from the vibration modes by mechanical–electrical oscillation of the metal sheet in corresponding to converse piezoelectric effect using a single-phase AC voltage power. Where the relative elliptic motion was occurred between the bearing seat and rotor in order to kinematical delivery, the rotor being driven was connected directly on the bearing seat to transmit the dynamic power with frictional contact force. In analysis of dynamic features, the system transfer function of admittance and equivalent circuit was obtained. The rotating speed of the prototype motor could be reached as high as 2000 rpm on the driving condition of 72 kHz, ±10 V_pp, and 0.2 A. The maximum torque was less than 0.003 N m. It could be utilized in the driver of CD, or the cooling fan in the computer CPU.     

Magnetoelectric effect in laminates of polymer-based pseudo-1–3 (Tb0.3Dy0.7)0.5Pr0.5Fe1.55 composite and?0.3Pb(Mg1/3Nb2/3)O3–0.7PbTiO3 single crystal

We report an extrinsic magnetoelectric effect in composite laminates made by sandwiching one thickness-polarized 0.7Pb(Mg_1/3Nb_2/3)O₃–0.3PbTiO₃ (PMN–PT) piezoelectric single crystal plate between two length-magnetized, polymer-based pseudo-1–3 (Tb_0.3Dy_0.7)_0.5Pr_0.5Fe_1.55 magnetostrictive composite plates. The laminates exhibit large magnetoelectric voltage coefficients (α _V ) of ∼0.17 V/Oe with a flat response for frequencies in excess of 40 kHz and of ∼2.97 V/Oe at the natural resonance frequency of ∼65 kHz. The distinct advantages of the laminates include high magnetic field sensitivity, low Joule heating loss, wide operating bandwidth, and low cost.     

Design and construction of shaft-driving type piezoceramic ultrasonic motor

A new approach in design of shaft-driving type piezoceramic ultrasonic motor is proposed. The stator of motor consisted of a commercial available buzzer disk in which a piezoceramic membrane is adhered to a metal sheet. The wave propagation on the metal sheet was generated by extended-shrunk force from piezoceramic oscillation. Driving energy came from the vibration modes by mechanical-electrical oscillation of the metal sheet in corresponding to converse piezoelectric effect using a single-phase AC voltage power. Where the relative elliptic motion was occurred between the bearing seat and rotor in order to kinematical delivery, the rotor being driven was connected directly on the bearing seat to transmit the dynamic power with frictional contact force. In analysis of dynamic features, the system transfer function of admittance and equivalent circuit was obtained. The rotating speed of the prototype motor could be reached as high as 2000 rpm on the driving condition of 72 kHz, +/-10 V(pp), and 0.2 A. The maximum torque was less than 0.003 Nm. It could be utilized in the driver of CD, or the cooling fan in the computer CPU.     

Modeling of functionally graded piezoelectric ultrasonic transducers

The application of functionally graded material (FGM) concept to piezoelectric transducers allows the design of composite transducers without interfaces, due to the continuous change of property values. Thus, large improvements can be achieved, as reduction of stress concentration, increasing of bonding strength, and bandwidth. This work proposes to design and to model FGM piezoelectric transducers and to compare their performance with non-FGM ones. Analytical and finite element (FE) modeling of FGM piezoelectric transducers radiating a plane pressure wave in fluid medium are developed and their results are compared. The ANSYS software is used for the FE modeling. The analytical model is based on FGM-equivalent acoustic transmission-line model, which is implemented using MATLAB software. Two cases are considered: (i) the transducer emits a pressure wave in water and it is composed of a graded piezoceramic disk, and backing and matching layers made of homogeneous materials; (ii) the transducer has no backing and matching layer; in this case, no external load is simulated. Time and frequency pressure responses are obtained through a transient analysis. The material properties are graded along thickness direction. Linear and exponential gradation functions are implemented to illustrate the influence of gradation on the transducer pressure response, electrical impedance, and resonance frequencies.     

磁致伸缩/压电层叠复合材料磁电效应分析

采用有限元分析软件COMSOL5.0建立了三维悬臂梁模型,分析了磁致伸缩/压电/磁致伸缩叠层复合材料的磁电系数α_(ME),并就几何参数对复合结构磁电系数的影响进行了优化分析.首先,利用稳态求解器研究了磁电层状复合结构内部的应力、应变、位移以及电势分布情况,利用瞬态求解分析了磁电复合结构各变量动态分布规律;其次,应用小信号频域分析研究了该结构的谐振频率以及在不同偏置磁场对输出电压的影响,结果表明,随着直流偏置磁场的增加,输出电压逐渐减小.改变复合材料不同层的厚度,分析了磁电层与压电层厚度比t_m/t_p对磁电系数的影响,结果表明,随着厚度比增加,α_(ME)逐渐增大,其增加速率逐渐减小;最后,分析了磁电系数α_(ME)随复合结构面积、长宽比的变化情况.分析表明,α_(ME)随磁电复合结构面积的增加逐渐增加,其增加速率逐渐减小;当磁电复合结构面积恒定时,其磁电系数随长宽比L/W增加表现出先增加后减小的趋势,存在最优值.     

Analysis of a single-mode optical fibre piezoceramic phase modulator

The behaviour of a cylindrical single-mode optical fibre piezoceramic phase modulator was investigated in the frequency range below resonance. The integral and differential phase modulation efficiencies are reported for different geometrical dimensions of the modulator and for various piezoelectric ceramic materials. p ]The results obtained show that a phase-modulation depth in excess of can be easily achieved using commercially available piezoelectric cylinders, with driving voltage amplitude as low as 5 V.     

(Pb0.85Sm0.10)(Ti0.98Mn0.02)O3压电陶瓷超高各向异性机电耦合性能的X射线衍射研究

本文用X射线衍射技术研究了具有典型超高各向异性机电耦合性能的Sm改性PbTiO₃压电陶瓷。通过引入面网取向密度指数ρ_(hkl)和建立90°电畴转向畴壁平移模型,就改性PbTiO₃陶瓷圆片经不同电压极化后材料内部电畴结构变化作了定量的分析与讨论。结果表明,在改性PbTiO₃陶瓷结构中,90°畴壁空间取向分布具有高度的择优性;极化处理使材料中90°电畴壁显著平移,但其取向分布变化甚少;材料的纵向机电耦合系数K_t与(002)面网取向密度指数增量△ρ₍₀₀₂₎具有基本平行的电场依赖关系。 关键词：     

圆环状复合材料高频宽带水声换能器

研制了一种圆环状高频宽带水声换能器。利用压电复合材料Q值低从而频带宽的特点,采用双环轴向堆叠产生双模态耦合的结构方式拓宽换能器的带宽。通过理论分析与仿真计算,确定敏感元件几何尺寸。用切割-浇注-被覆电极等工艺制备出压电复合材料圆环;再将制备出的外径相同,壁厚不等的压电复合材料圆环轴向叠堆制成叠堆敏感元件,最后灌注防水透声层制成换能器。对制得的换能器进行水下性能测试,测得该换能器谐振频率为410 kHz,最大发射电压响应为150 dB,-3 dB带宽达60 kHz,水平指向性开角(-5 dB)为360°,-3 dB垂直指向性开角约20°。结果表明将复合材料圆环轴向堆叠可显著拓展换能器的带宽,且实现声波的水平全向发射。      

A longitudinal (1−x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 single-crystal piezoelectric transformer

In present work, a simple longitudinal piezoelectric transformer with the size of 16-mm length, 2-mm width, and 2-mm thickness was designed and fabricated with relaxor ferroelectric single-crystal (1−x)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃. Both the input and output parts utilized the ultrahigh longitudinal extensional electromechanical coupling coefficients. Compared to the Rosen-type transformer, this transformer has the advantages of smaller-size, simpler structure, no spurious vibration, and no acoustic mismatch between the input and output parts. The electrical measurement results indicated that under the resonance frequency of 114 kHz, a step-up voltage of about 30 can be obtained under a 10-MΩ load resistance, which agreed well with the calculated results. Besides, the frequency and load dependences of this transformer were also systematically studied and discussed. The results indicated that this transformer has potential applications in the small-size high-voltage amplifier and magnetoelectric/piezoelectric-transformer composite transducers.     

Piezoelectric diaphragm for vibration energy harvesting

This paper presents a technique of electric energy generation using a mechanically excited unimorph piezoelectric membrane transducer. The electrical characteristics of the piezoelectric power generator are investigated under dynamic conditions. The electromechanical model of the generator is presented and used to predict its electrical performances. The experiments was performed with a piezoelectric actuator (shaker) moving a macroscopic 25 mm diameter piezoelectric membrane. A power of 0.65 mW was generated at the resonance frequency (1.71 kHz) across a 5.6 kOmega optimal resistor and for a 80 N force. A special electronic circuit has been conceived in order to increase the power harvested by the piezoelectric transducer. This electrical converter applies the SSHI (synchronized switch harvesting on inductor) technique, and leads to remarkable results: under the same actuation conditions the generated power reaches 1.7 mW, which is sufficient to supply a large range of low consumption sensors.     

Magnetoelectric effect in composites of magnet,metal-cap,and piezoceramic

We report on the magnetoelectric (ME) effect in three-phase magnet-metal-cap-piezoceramic composites of a thickness-polarized Pb(Zr,Ti)O₃ disk bonded between two truncated conical brass caps and two thickness-magnetized NdFeB magnets along the thickness direction. The effect originated from the product of the magnetic attractive–repellent effect in the magnets and the amplified piezoelectric effect in the cap-disk assembly. The composites exhibited a ME voltage coefficient α_V of ∼2.6 mV/Oe in the non-resonance frequency range of 0.1–10 kHz with good voltage-field linearity in the field range of 10^-3–10 Oe, besides an enhanced α_V of 167.4 mV/Oe at a resonance frequency of 14.4 kHz. Compared to conventional two-phase and three-phase magnetostrictive material-contained ME composites, these composites possessed two distinct benefits of higher property-tailorable flexibility and requiring no external dc bias magnetic field to enable an obvious α_V. PACS 77.84.-S; 75.80.+q; 77.84.Dy; 77.65.-j; 85.80.Jm     

Metal nanowires fabricated by means of magnetostrictive actuator

A new method of fabricating nanowires for electric conductance quantization studies is proposed as an alternative to the method based on converse piezoelectric effect. Commonly used for nanowire fabrication, piezoelectric actuators are expensive and require high-level voltage control signal. The method presented in this paper is based on the use of magnetostrictive actuator. Both the actuator structure and the method of the conversion factor measurement are discussed. The results of the tests of the magnetostrictive actuator are also reported. The parameters of the proposed actuator are compared with those of its piezoelectric counterpart used to date. The results of measurement confirm that the proposed actuator can be used for studying electric conductance quantization in nanowires. Presented at the X-th Symposium on Surface Physics, Prague, Czech Republic, July 11–15, 2005     

Ultrasonic micro-motor using miniature piezoelectric tube with diameter of 1.0 mm

At the present moment, the smallest piezoelectric ultrasonic micro-motors utilizing miniature PZT piezoelectric ceramic tubes were developed. The motor consists of a PZT-metal composite tube stator, two steel rotors and a thin shaft that keeps the two rotors pressing on both ends of the stator elastically. The dimensions of the PZT tube are 1.0 mm in outer diameter, 0.6 mm in inner diameter and 5.0 mm in length. The diameter and total length of the assembled micro-motor is 1.0 mm and 8 mm (including an adjusting spring), respectively. The tube-type micro-motor is driven by two pairs of alternative voltages with phase shift 90 degrees between the adjacent electrodes and operated in the first circular-bending vibration mode of the stator with the resonance frequency about 58 kHz. The experimental results show that the tube-type micro-motors have perfect performances: (i) high rotation frequency over 3000 rpm and (ii) large starting torque over 7.8 microN m under the conditions of the input voltage of 110 V(p-p) and the resonance frequency. The micro-motor is well suitable for operating in micro-spaces, such as in intravascular, micro-robots and micro-craft applications.