Working-point control method for readout of dynamic phase changes in interferometric fiber-optic sensors by tuning the laser frequency

A simple but reliable method, namely the working-point control by tuning the laser frequency, for the dynamic phase shift measurement in a passive homodyne interferometric fiber-optic sensor is proposed. A dc voltage calculated from the photodetector output is applied to the light source to control the interferometer at the condition of maximum sensitivity. Then the signal's phase shift can be obtained from the components of zero and fundamental frequencies. To test the method, an all polarization-maintaining Mach-Zehnder interferometer with a piezoelectric ceramic (PbZrTiO(3), or PZT) cylinder in one arm is constructed. The experimental results show that the simulation signal's phase shift generated by the PZT cylinder can be read out correctly with the method. It has the advantages of simplicities of operation, no-active element in the sensing head, and large operating bandwidth. It can be used for readout of dynamic phase shifts in various interferometric fiber-optic sensors.     

A planar unimorph-based actuator with large vertical displacement capability. I. Experiment

A piezoelectric actuator utilizing a planar arrangement of unimorph elements that produces displacements perpendicular to the plane of the actuator is described. The elements are connected in series mechanically so that the vertical displacement of each element adds to the vertical displacements of the other elements. Two prototype actuators were built and tested. One was stick-built from individual bars of PZT and aluminum, which were epoxied together and connected to each other with short aluminum connector bars. The other was fabricated monolithically from a single plate of PZT by bead-blasting the PZT plate through a steel shadowmask to mill out the desired actuator shape. Copper bars epoxied to the milled-out PZT bars then formed the unimorph elements. The unloaded output displacement of each actuator versus applied voltage was measured as well as the displacement versus applied force with no applied voltage. These measurements were in agreement with the predictions of an electromechanical model of the actuator that has been developed. The model predicted and measurements verified that stiffeners can be added to the basic geometry that will significantly increase the force output without affecting the displacement versus applied voltage characteristic.     

PIMNT单晶弯曲圆盘换能器设计

新型弛豫铁电单晶材料铌铟酸铅-铌镁酸铅-钛酸铅晶体(Pb(In_1/2Nb_1/2) O₃-Pb(Mg_1/3Nb_2/3) O₃-PbTiO₃, PIMNT)的压电系数是陶瓷材料的 6 倍以上,应变量高出压电陶瓷 10 倍以上,具有较高的机电耦合系数,压电性能优于传统 PZT 材料。文章将单晶材料应用于带空气腔的弯曲圆盘换能器中,利用 ANSYS 仿真软件优化换能器结构,确定换能器尺寸,设计制作 PIMNT 压电单晶换能器和PZT4压电陶瓷换能器,并进行了水池实验。换能器实测结果与仿真结果保持一致,单晶换能器的谐振频率为 2.85 kHz,最大发送电压响应为 136.3 dB。结果表明,相比于同尺寸的陶瓷换能器,将 PIMNT 压电单晶应用于弯曲圆盘换能器可降低谐振频率,提高发送电压响应,提升换能器的工作性能,为进一步改善单晶换能器综合性能提供参考。     

Modeling and fabrication of a piezoelectric vibration‐induced micro power generator

Abstract

In this paper, theoretical and experimental study on a piezoelectric vibration‐induced micro power generator that can convert mechanical vibration energy into electrical energy is presented. The mechanical‐electrical energy conversion mechanism is a voltage between two capacitors, which belong to the mechanical and the piezoelectric equivalent circuits, respectively. To verify the theoretical analysis, two clusters of transducer structures are fabricated. Piezoelectric lead zirconate titanate (PZT) material is chosen to make the energy conversion transducer. The desired shape of the piezoelectric generator with its resonance frequency in accordance with the ambient vibration source is designed by finite element analysis (FEA).

Experimental results show that the maximum output voltages are generated at the first mode resonance frequencies of the structure. The overall conversion efficiency is measured to be 33%. The experimental results coincide with the theoretical analysis.     

Nondestructive Evaluation on Strain Sensing Capability of Piezoelectric Sensors for Structural Health Monitoring

A kind of strain-sensing-based piezoelectric sensor was fabricated, and the mixture of cement powder and epoxy resin was used as the packaging layer. A nondestructive strain sensitivity testing method based on strain-sensing capability of piezoelectric sensor is presented. The theoretical foundation indicates that output voltage of piezoelectric sensor and strain of structure keep linear relationship when corresponding parameters are ascertained. Quasi-static responses and low-frequency (0–40 Hz) dynamic responses of piezoelectric sensors and strain gauges are analyzed. The results show that the piezoelectric sensors are sensitive and can accurately reflect the strain variation of structures. The quantification of output voltage and strain is investigated, and quasi-static and dynamic sensitivities were acquired (159.52–515.48 mV/με). With increasing of vibration frequency, the area of hysteresis loop decreases, and the strain sensitivity of sensor increases. Combining sensitivities with output voltages of sensors, the strain variation of structures could be obtained, which exhibit great application potentials of piezoelectric sensors for structural strain monitoring in low-frequency vibrations in civil engineering.     

Flexible highly-effective energy harvester via crystallographic and computational control of nanointerfacial morphotropic piezoelectric thin film

Controlling the properties of piezoelectric thin films is a key aspect for designing highly effident flexible electromechanical devices.In this stud~ the crystallographic phenomena of PbZr1-xTixO3 (PZT) thin films caused by distinguished interfacial effects are deeply investigated by overlooking views,including not only an experimental demonstration but also ab initio modeling.The polymorphic phase balance and crystallinity,as well as the crystal orientation of PZT thin films at the morphotropic phase boundary (MPB),can be stably modulated using interfacial crystal structures.Here,interactions with MgO stabilize the PZT crystallographic system well and induce the texturing influences,while the PZT film remains quasi-stable on a conventional Al2O3 wafer.On the basis of this fundamental understanding,a high-output flexible energy harvester is developed using the controlled-PZT system,which shows significantly higher performance than the unmodified PZT generator.The voltage,current,and power densities are improved by 556％,503％,and 822％,respectively,in comparison with the previous flexional single-crystalline piezoelectric device.Finally,the improved flexible generator is applied to harvest tiny vibrational energy from a real traffic system,and it is used to operate a commercial electronic unit.These results clearly indicate that atomic-scale designs can produce significant impacts on macroscopic applications.     

力电多场鼓包法测定PZT铁电薄膜的横向压电系数

为表征Pb(Zr_(0.52)Ti_(0.48))O_3(PZT)薄膜的横向压电性能,以纯力场鼓包测试模型和铁电薄膜材料压电方程为基础,推导了PZT铁电薄膜的力电耦合鼓包本构模型。采用溶胶-凝胶法制备了PZT铁电薄膜,并通过化学腐蚀法获得PZT薄膜鼓包样品。在外加电压为0~14V的条件下进行鼓包测试。结果表明,在纯力场作用下,PZT薄膜的弹性模量和残余应力分别为91.9GPa和36.2MPa;随着电压从2V变化到14V,PZT薄膜的横向压电系数d31从-28.9pm/V变化到-45.8pm/V。本工作所发展的力电耦合鼓包测试技术及力电耦合鼓包本构模型为评价铁电薄膜材料的横向压电性能提供了一种有效的分析方法。     

Characterization of sol-gel Pb(Zr0.53Ti0.47O3) in thin film bulk acoustic resonators

The behavior of {f111g}-textured Pb(Zr(0.53Ti0.47O3) (PZT) deposited by the sol-gel technique in thin film bulk acoustic resonators (TFBAR's) was investigated at a resonance frequency of about 1 GHz. The resonators were fabricated on Si wafers using deep silicon etching to create a membrane structure and using platinum as top and bottom electrodes. The best response of the resonators was observed at a bias voltage of -15 kV/cm with values of about 10% for the coupling constant and about 50 for the quality factor. This voltage corresponds to optimal values of piezoelectric constant d33 and dielectric constant measured as a function of the electric field. The influence of a bias voltage on the resonance frequency, antiresonance frequency, and coupling constant were observed. Both the resonance and antiresonance frequency show a hysteretic change with applied bias. This effect can be used to shift the whole band of a filter by applying a voltage. The TFBAR structure also allowed us to extract values for materials parameters of the PZT film. Dielectric, piezoelectric, and elastic properties of the f111g-textured PZT film are reported and compared to direct measurements and to literature values.     

Electromechanical properties of lead zirconate titanate piezoceramics under the influence of mechanical stresses

In lead zirconate titanate piezoceramics, external stresses can cause substantial changes in the piezoelectric coefficients, dielectric constant, and elastic compliance due to nonlinear effects and stress depoling effects. In both soft and hard PZT piezoceramics, the aging can produce a memory effect that will facilitate the recovery of the poled state in the ceramics from momentary electric or stress depoling. In hard PZT ceramics, the local defect fields built up during the aging process can stabilize the ceramic against external stress depoling that results in a marked increase in the piezoelectric coefficient and electromechanical coupling factor in the ceramic under the stress. Although soft PZT ceramics can be easily stress depoled (losing piezoelectricity), a DC bias electric field, parallel to the original poling direction, can be employed to maintain the ceramic poling state so that the ceramic can be used at high stresses without depoling.     

Effect of material constants on power output in piezoelectric vibration-based generators

A possible power output estimation based on material constants in piezoelectric vibration-based generators is proposed. A modified equivalent circuit model of the generator was built and was validated by the measurement results in the generator fabricated using potassium sodium niobate-based and lead zirconate titanate (PZT) ceramics. Subsequently, generators with the same structure using other PZT-based and bismuth-layered structure ferroelectrics ceramics were fabricated and tested. The power outputs of these generators were expressed as a linear functions of the term composed of electromechanical coupling coefficients k(sys)(2) and mechanical quality factors Q*(m) of the generator. The relationship between device constants (k(sys)(2) and Q*(m)) and material constants (k(31)(2) and Q(m)) was clarified. Estimation of the power output using material constants is demonstrated and the appropriate piezoelectric material for the generator is suggested.     

Dynamic stability of modified strain gradient theory sinusoidal viscoelastic piezoelectric polymeric functionally graded single-walled carbon nanotubes reinforced nanocomposite plate considering surface stress and agglomeration effects under hydro-thermo-electro-magneto-mechanical loadings

In this article, dynamic stability analysis of the viscoelastic piezoelectric polymeric nanocomposite plate reinforced by functionally graded single-walled carbon nanotubes (FG-SWCNTs) based on modified strain gradient theory (MSGT) is explored. The viscoelastic piezoelectric polymeric nanocomposite plate reinforced is subjected to hydrothermal and electro-magneto-mechanical loadings. The viscoelastic piezoelectric polymeric nanocomposite plate is rested on viscoelastic foundation. Uniform distribution (UD), various functionally graded (FG) distribution types such as FG-V, FG-X, and FG-O are considered for single-walled carbon nanotubes (SWCNTs). The extended mixture approach is applied to estimation of the elastic properties. The equations of motion are derived by Hamilton's principle. The resonance frequency or the parametric resonance is obtained then dynamic stability region is specified. There is a good agreement between the present work and the literature result. Various parametric investigations are performed for the influences of the small scale parameters, direct and alternating applied voltage, magnetic field, viscoelastic foundation coefficients, and aspect ratios on the dynamic stability region of the viscoelastic piezoelectric polymeric nanocomposite plate. The results indicated that SWCNT agglomeration and surface stress have significant effects on the dynamic stability region and the parametric resonance. Dynamic stability region increases with increasing of thickness to width ratio, magnetic field, applied voltage, static load factor, viscoelastic foundation parameters, and surface density constant, and decreasing of length to width ratio and residual surface stress constant. Also, the dynamic stability region shifts to lower parameter resonance with increasing of temperature and moisture changes. The results can be employed for design of micro-electro-mechanical systems and nano-electro-mechanical systems.     

钝体结构对纵振式压电气流发电机性能的影响

为满足管道监测系统的自供电需求,提出一种复合钝体扰流纵振式压电气流发电机.介绍了发电机的结构、工作原理.通过理论分析与实验测试研究了钝体结构对其性能的影响,证明了发电机原理的可行性.研究结果表明:平均阻力随流速及直径比增加呈二次方增长,平均阻力系数随直径比的增大而增大,最后趋于稳定(5.34);对于柔性钝体发电机,直径...     

Experimental and numerical results of dynamics behavior of a nonlinear piezoelectric beam

This article presents a numerical formulation and experimental implementation for the dynamics behavior verification of the nonlinear piezoelectric beam through harmonic excitation. The nonlinear piezoelectric beam dynamic analysis program is developed with MATLAB software. To verify the nonlinear piezoelectric beam dynamic analysis results, the experimental results are used for the vibration analysis of a piezoelectric beam to the harmonic excitation of the base of the beam. Then, the piezoelectric effect on the output voltage, velocity, acceleration values, and the time response are obtained. Afterwards, the effects of the excitation velocity and the position of concentrated mass on the output voltage are verified.     

基于PZT薄膜面内极化工作的低应力压电微传声器

本文设计、制作并测试了一种基于压电PZT薄膜面内极化工作的压电微传声器.利用压电薄膜的纵向压电常数,并通过压电微传声器面内电极的设计提高电极间距,以提高压电微传声器的灵敏度.由于基于PZT薄膜的多层结构常具有很大的残余应力,通过5种不同振动膜材料与PZT薄膜的应力匹配实验,研究了降低振动膜应力的方法.结果表明,对于相同尺寸的膜片,PZT/ZrO2/LTO/Si3N4具有最小的变形,其中心处的变形(200 nm)仅为膜片PZT/ZrO2/Si3N4/SiO2中心处变形(17μm)的1%.采用体硅微加工工艺制作了具有方形振动膜(2 mm×2 mm)的压电微传声器结构,采用LTO/Si3N4多层结构作为振动膜结构,方形膜片中心的圆形结构为PZT薄膜,环形叉指结构为Au/Cr电极.压电微传声器在0.15 kHz~6 kHz频率范围内的灵敏度约为0.1 mV/Pa.     

Design and fabrication of functionally graded PZT/Pt piezoelectric bimorph actuator

A laminated piezoelectric bimorph actuator with a graded compositional distribution of PZT and Pt was fabricated, and its deflection characteristics were evaluated. Using experimentally determined compositional dependency of elastic and piezoelectric properties in the PZT/Pt composites, the modified classical lamination theory and the finite element method were applied to find the optimum compositional profile that will give a larger deflection and smaller stress, simultaneously. The miniature bimorph-type graded actuator that consists of a composite internal-electrode (PZT/30 vol% Pt) and three piezoelectric layers of different compositions (PZT/0–20 vol% Pt) were fabricated by powder stacking and sintering. The deflection of the actuator was measured using electric strain gages mounted on the top and bottom surfaces of the actuator. The deflection was found to strongly depend on the composition distribution profile. Under an applied electric field of 100 V m^–1, the actuator with an optimum composition profile exhibited a curvature of up to 0.03 m^–1, which is a satisfactory performance for this kind of actuators. The stress generated on actuation was estimated to be as low as 0.4 MPa, which is much smaller than those of conventional directly bonded actuators and will assure a long actuation life.     

High-displacement piezoelectric actuator utilizing a meander-line geometry I. Experimental characterization

The compact linear-motion piezoelectric actuator developed has relatively large displacement capabilities. It is composed of a number of parallel bars of lead zirconium titanate (PZT) connected together in a meander-line configuration so that they are mechanically in series and electrically in parallel. The polarity of the adjacent bars is arranged so that if a given bar expands under the applied voltage, the adjacent bars contract. An electromechanical model of the actuator predicted and measurements verified that stiffeners added to the basic meander line geometry significantly increased the force output without affecting the displacement versus applied voltage relationship.     

Novel Digital Voltage Ramp Generator for Use in Precision Current Sources in the Picoampere Range

We report on the development of a novel highly linear voltage ramp generator to be used for the traceable calibration of picoamperemeters. The generator is based on two digital-to-analog converters, one of them being used to compensate for the differential nonlinearity of the other one. The generator is completely controllable by a computer, its voltage slope $dV/dt$ is adjustable between 1 and 1000 mV/s. During a ramp running between $-$10 and $+$10 V, the slope shows a relative variation of only $1.3 cdot 10^{-5}$ (relative standard deviation). Due to a small output filter time constant of only 10 ms, we are, for the first time, able to conduct dynamic measurements of picoamperemeters with no sacrifice of linearity.      

Detection and response characteristics of giant magnetostrictive/piezoelectric laminated cantilevers under cyclic bending

We examine the detection and response characteristics of giant magnetostrictive/piezoelectric laminated cantilevers under cyclic bending in a combined numerical and experimental approach. The laminate is fabricated using thin Terfenol-D and PZT layers. Three-dimensional finite element analysis was conducted, and the dynamic electromagneto-mechanical fields in the two-layered magnetostrictive/piezoelectric laminate were predicted by introducing a second-order magnetoelastic constant of Terfenol-D. The tip deflection, induced voltage, and induced magnetic field were also measured, and experimental data were compared with numerical simulations to verify the model. The effects of load ratio and frequency on the dynamic electromagneto-mechanical fields were then discussed in detail. The finite element method is shown to be capable of estimating the dynamic electromagneto-mechanical fields in the giant magnetostrictive/piezoelectric laminated cantilevers, making it a useful tool for designing future electronic devices with self-sensing or energy harvesting capabilities.     

A numerical study on anomalous behavior of piezoelectric response in functionally graded materials

Finite element-based simulations have been performed on piezoelectric-based functionally graded materials (FGM). PZT (Lead zirconate titanate) and PVDF (Polyvinylidene fluoride) FGM composites have been investigated. Anomalous enhancement in output voltage has been observed at grading index n = 0.05 (Voltage = 210 V), which is 105 and 185% higher than the original material at n = 0 (PVDF) and n = ∞ (PZT), respectively. Further, role of Young’s modulus, dielectric constant, and piezoelectric constant was systematically investigated to understand this enhancement. It is found that performance of FGM not only relies on piezoelectric constants but also largely depends upon values of Young’s modulus and dielectric constant.     

0-3型橡胶基压电阻尼复合材料的制备及其性能

本文以通用橡胶为基体材料,以一定体积分数的锆钛酸铅粉体（PZT）为压电相、导电炭黑为导电相制备了0-3型压电阻尼复合材料。经过直流高温油浴极化处理后,获得了在低频下具有较高损耗因子的压电阻尼材料,并研究了其断面形貌、压电应变系数、损耗因子等各项性能。