新型纳米分辨率位移定位平移台的研制

为克服已有压电驱动器存在的结构及控制系统复杂、定位行程小等缺陷,利用压电陶瓷的逆压电效应设计并制作了一种新型的压电纳米步进驱动器,建立光栅测试系统对这种压电驱动器的动态性能进行了测试.将压电纳米步进驱动器与电磁伺服马达耦合,设计新颖驱动结构,利用微机通过步进运动控制卡统一控制,实现大范围一维纳米分辨率位移定位.系统样机解决了所研制压电纳米步进驱动器双向运动、实用定位等问题.位移定位分辨率为50 nm,定位行程为100mm,纳米分辨率定位最大速度为0.6 mm/s.     

电液主动悬架单元测控技术研究

对由流量伺服阀构成的电液主动悬架进行了系统分析,设计了基于力、位移作为主要测量和反馈信号的PID控制器,仿真和台架实验结果表明,利用PID控制器进行电液流量伺服结构主动悬架控制,机构简单可靠,对于簧上质量加速度有明显的衰减作用.     

电液谐振式高频疲劳试验台动态特性研究

针对由单出杆液压缸与二位三通2D阀组成的电液谐振式高频疲劳试验台,因单出杆液压缸无杆腔与2D阀相连,有杆腔恒通油源。而2D阀突破常规电液伺服阀频宽极限,具有宽频带、高频响等特点,通过改变阀芯旋转速度及阀口轴向开度,可对系统分别进行变频、变幅控制。对采用2D阀控制技术的电液谐振式高频疲劳试验台建立数学、仿真模型,并对该试验台谐振工况进行仿真与实验研究,结果表明该系统谐振工况输出位移（载荷力）与激振力大,消耗外界功率低。     

基于电流控制的压电陶瓷驱动器

为了解决电压控制型压电陶瓷驱动器驱动压电陶瓷时存在的迟滞、蠕变和带宽窄的问题,设计了基于电流控制的压电陶瓷驱动器,利用压电陶瓷致动器位移与其所带电荷量间的线性关系,该驱动器通过控制压电陶瓷的充电电流和时间控制其位移量．在此基础上,提出了以分辨率换取稳定性的动态保持控制方法,采用该电流型驱动器,实现了开环下对压电陶瓷致动器的稳定、快速、高精度定位．实验结果表明,该驱动器驱动行程为10μm的压电陶瓷时,满行程带宽大于1．5kHz,重复定位精度小于4nm（0．4％）．     

大位移压电陶瓷驱动器的设计与试验

针对大位移压电陶瓷驱动器,研究了压电陶瓷双晶片的驱动效能。基于压电陶瓷材料的逆压电效应,应用压电陶瓷双晶片在机械自由、电学短路状态下,一片加正向电压缩短另一片加反向电压伸长共同作用产生弯曲变形,通过组合设计将压电陶瓷双晶片的弯曲变形位移叠加起来,实现了压电陶瓷驱动器的大位移输出。在相同电压的条件下,此压电陶瓷驱动器的输出位移量比叠层驱动器有较大的增加,达200μm,结构尺寸也大大减小。该驱动器不需要位移放大机构,可直接应用于有大位移要求的机构驱动。     

压电喷墨驱动器特性研究及参数优化

目的 研究压电驱动器结构参数对其驱动性能的影响,并对其结构进行优化,为进一步研究压电喷墨的喷射特性奠定基础.方法 总结近年来压电喷墨印刷技术的研究现状,利用有限元数值模拟软件Comsol Multiphysics建立压电驱动器的数值模型,分析压电薄膜PZT、SiO2振动板和Parylene保护层这3个部分的结构尺寸对压电驱动器位移的影响规律,并且利用正交试验方法确定压电驱动器主要部件的最优尺寸.结果 压电驱动器的结构尺寸对其振幅有较大影响,不同的结构组合可以得到不同的压电驱动器位移.在压电薄膜与振动板宽度之比为0.7,振动板宽度为140μm,保护层厚度为0.7μm,振动板厚度为0.9μm,压电薄膜厚度为1μm时,驱动器位移达到最大.结论 通过对压电驱动器的结构尺寸进行优化,可使驱动器位移达到最大,从而使其驱动性能最优.     

压电驱动器的非对称迟滞模型

为了补偿压电驱动器的非对称迟滞,提出了改进型Maxwell迟滞模型.Goldfarb提出的经典Maxwell迟滞模型由多个基础单元并联叠加而成,其基础单元为单个弹簧-物块单元,迟滞特性为平行四边形,故只能描述对称迟滞.为了能描述压电驱动器非对称迟滞,提出了基础单元迟滞特性为梯形的模型.为了简化算法程序,将梯形单元优化为两个三角形单元组合而成.为了验证该模型,以压电工作台为实验对象,运用该迟滞模型的逆模型进行迟滞补偿控制.单独的迟滞逆模型前馈开环控制实验结果表明,位移跟踪相对误差从7.37％降到了1.56％,输入输出基本呈线性关系.逆模型结合PID复合反馈闭环控制实验结果表明,位移跟踪相对误差进一步降低到0.53％,输入输出呈很好的线性关系.这表明本文所建立的迟滞模型能很好地描述压电驱动器非对称迟滞特性.     

激光干涉法测量微小振动

文章介绍用激光干涉法测量新型压电微驱动器动态位移响应的实验原理及方法。实验结果表明,这类PZN－PZT微驱动器不仅具有高的电压－位移灵敏度,而且其频响可高达1kHz,是一种很好的微驱动器件。     

压电陶瓷驱动器菱形位移放大机构的动态应变测量

为监测压电陶瓷驱动器并联驱动时各自的动态输出状态,利用压电陶瓷驱动器中位移放大机构的菱形对称结构建立全桥应变测量方法,通过位移放大机构菱边在振动过程中的动态应变变化来反映压电陶瓷驱动器的工作状态。对不同状态下位移放大机构菱边的动态应变进行实验研究,结果表明:利用位移放大机构对称菱边建立的全桥应变测量方法能够有效获取位移放大机构在振动过程中的动态应变变化,且能够对位移放大机构的运行状态进行实时监测,在带负载和不带负载情况下,设计的位移放大机构菱边在振动过程中的应变量级都在几个微应变,该测量结果也反映出设计的位移放大机构刚度较好,能够保证压电陶瓷驱动器有较好的输出性能。     

电液四轴高频结构强度疲劳试验系统

电液激振器受传统的电液伺服阀频响特性的限制,其激振频率难以提高,采用2D阀替代传统伺服阀组成电液激振器的方案,该激振器通过增加阀芯的旋转速度来提高其激振频率,同时将该电液激振器应用于4轴高频结构试验系统。对试验系统的结构和工作原理进行了分析讨论,包括频率、幅值和相位的控制方法。基于系统的频响仿真分析,提出了4个作动器的同步控制策略,对理论分析进行实验验证。试验结果表明:该电液四轴强度疲劳试验系统能在40 Hz~200 Hz范围内对试验对象进行同步加载试验,其频率、幅值连续可控。     

Analytical solutions for the transverse deflection of a piezoelectric circular axisymmetric unimorph actuator

This paper presents analytical solutions to the transverse deformation shape of a circular axisymmetric piezoelectric-metal composite unimorph actuator. The solutions account for both the influence of an applied electric field and a concentrated or uniformly distributed mechanical load. Using piezoelectric constitutive equations, combined with thin plate and small bending elastic theory, the generalized equation of motion for bending of thin piezoelectric-metal composite plates has been derived. Our approach predicts that there is an optimum thickness ratio between the piezoelectric and metal plates, which leads to a maximum combination of deflection and load carrying capabilities. Derived formulas are very simple that offer a quick method for engineering design and optimization of a circular unimorph piezoelectric actuator.     

Optimization of a circular thin-film piezoelectric actuator lying on a clamped multilayered elastic plate

A system consisting of a circular multilayered thin-film elastic plate and a piezoelectric actuator, which is generally used for ultrasound generation in air, is studied in this paper. Effects of the electrode dimension of a circular thinfilm piezoelectric actuator lying on a clamped multilayered elastic plate are discussed theoretically, while the first-order theory of asymmetrically laminated piezoelectric plates with consideration of coupled extension and flexure of the reference plane is used. Numerical results show that the deflection of the elastic plate can be optimized by adjusting the radius of the top electrode.     

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.     

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.     

Electromechanical coupling and output efficiency of piezoelectric bending actuators

Electromechanical coupling mechanisms in piezoelectric bending actuators are discussed in this paper based on the constitutive equations of cantilever bimorph and unimorph actuators. Three actuator characteristic parameters, (e.g., electromechanical coupling coefficient, maximum energy transmission coefficient, and maximum mechanical output energy) are discussed for cantilever bimorph and unimorph actuators. In the case of the bimorph actuator, if the effect of the bonding layer is negligible, these parameters are directly related to the transverse coupling factor lest. In the case of the unimorph actuator, these parameters also depend on the Young's modulus and the thickness of the elastic layer. Maximum values for these parameters can be obtained by choosing proper thickness ratio and Young's modulus ratio of elastic and piezoelectric layers. Calculation results on four unimorph actuators indicate that the use of stiffer elastic material is preferred to increase electromechanical coupling and output mechanical energy in unimorph actuators.     

A planar unimorph-based actuator with large vertical displacement capability. II. Theory

A piezoelectric actuator utilizing a planar trellis-like arrangement of multiple unimorph elements is described which produces displacements perpendicular to the plane of the actuator. The unimorph elements are connected in series mechanically so that the vertical displacement of each unimorph element in the structure adds to the vertical displacements of the other elements, resulting in a large overall vertical displacement at the output of the actuator. A simple electromechanical model of the actuator is developed. The model consists of a voltage-actuated force source, which is the result of the piezoelectric properties of the unimorph bars that make up the actuator, in parallel mechanically with a stiff spring that models the elastic response, both bending and twisting, of the unimorph elements. The long moment arms inherent in the geometry of the actuator make a substantial contribution to the overall compliance of the actuator. The addition of stiffeners to the actuator can significantly reduce the effect of these moment arms, and thus substantially increase the stiffness of the actuator. As a result, the force generation capability of the actuator is significantly increased without affecting its displacement capability.     

层合板中压电作动器最优厚度和嵌入位置研究

研究了压电结构中压电片厚度和嵌入深度的优化问题。首先给出了压电层合板的高阶耦合分析模型;然后以不受约束的含压电铺层复合材料板为代表,在压电层厚度方向施加电场时板自由变形,假设板任意微元横截面上内力为零,以其弯(扭)曲曲率最大为优化目标,建立了求解压电片最优厚度和嵌入深度问题的约束优化模型。最后分别以各向同性板中嵌入各项同性压电片和复合材料板中嵌入各向异性压电片为例进行了分析,绘出了目标函数的三维曲面图及等高线图,结果表明压电片的作动效能与其厚度和嵌入位置密切相关,而最优厚度和嵌入位置是由压电片和基体的材料特性决定的。     

Multi-objective optimization of a triple layer piezoelectric bender with a flexible extension using genetic algorithm

This article presents an electromechanical analysis for a piezoelectric bimorph actuator with a flexible extension, which is used to increase the tip deflection. The performance measuring attributes of such an actuator are derived, and a genetic algorithm is used for multi-objective optimization. The analysis reveals that for a thick flexible extension, the length of the extension provides Pareto optimal solutions for multi-objective optimization. The analysis also shows that as the thickness of the flexible extension decreases, the Pareto optimal solutions converge to a single solution for multi-objective optimization. We have considered nonlinear deflection behavior of piezoelectric materials at high electric fields, and series and parallel electrical connections in the analysis.     

书本式压电作动器的特性分析

在考虑粘接层影响的情形下，利用层合梁理论导出了柱形弯曲书本式压电作动器的作动力以及机电耦合系数的数学表达式，并通过数值仿真分析揭示了机电耦合系数与压电层层数、压电层厚度以及粘接层厚度间的关系。这些结果为书本式压电作动器的结构综合优化设计提供了理论基础。     

The Simulation of Diaphragm Deflection Actuated by Shear Mode Piezoelectric Actuator in Microdroplet Ejector

A shear mode piezoelectric actuator is applied to deflect the diaphragm of pressure chamber in the droplet ejector or inkjet printhead. The deflection of the bulge-diaphragm and resulting swept volume is analyzed by analytical and numerical method. With free-body treatment of the model, the analytical exact solutions for the two free bodies of bulge-diaphragm and piezoelectric beam were obtained. Also, the numerical solution by ANSYS is obtained to verify the analytical result. Besides, the whole-model solution coupling the bulge-diaphragm and piezoelectric beam together was obtained by ANSYS to compare with the result of free-body analysis. In order to estimate the maximum actuating force and deflection of the shear mode piezoelectric actuator, the diaphragm characteristic curve is obtained in the free-body analysis, which presents the decreasing tendency of the central deflection with the increase of anti-deflection (or reaction) force under certain actuating voltage. Also, the diaphragm characteristic curve is obtained showing the central deflection in proportion to the action force. By combining both kinds of curves, the actuated central deflection of the bulge-diaphragm can be obtained under certain actuating voltage. Finally, both linear relations including diaphragm central deflection in proportion to actuating voltage and volume displacement in proportion to diaphragm central deflection are obtained.