电流变液与压电陶瓷复合的自适应阻尼器设计和...

设计制作了两种电流变液与压电陶瓷复合的自适应阻尼器,其特点是：压电陶瓷响应振动产生高电压,用这个高电压直接去激励固化阻尼器内的电流变液实现了阻尼的自动调节。随着振动频率,振幅的变化,电流变液的响应改变,形成对振动的自适应控制。     

自耦合电流变阻尼器及其性能

电流变液与压电陶瓷组合的阻尼器是一种自耦合阻尼器。对直压式自耦合电流变阻尼器的性能进行了理论计算,并制作了直压式自耦合电流变液阻尼器。性能测试表明:压电陶瓷激励了电流变液;电流变液阻尼的变化改变了阻尼器的共振频率,并使振动幅度降低最高达30％。     

自供能电流变弹性体减振器的设计与特性分析

新型智能材料电流变弹性体是电流变材料的衍生体,兼有电流变液和弹性体的优点,在主被动的振动控制领域中有着极大的应用前景。基于电流变弹性体的刚度和阻尼可电控调节的特性以及压电陶瓷的正压电效应,研制一种基于D33挤压模式的压电自供能电流变弹性体减振器,并对其在不同激励和场强下的振动响应特性进行实验分析。试验数据表明相比无场强条件下,在压电供电和1 000 V恒压的条件下能有效增大电流变弹性体结构阻尼,改变减振器振动响应谱峰值的频率和幅值,提高系统的隔振效果。     

基于电流变液的机械臂控制系统设计与仿真

电流变液作为可变粘性阻尼器可实现系统的抑振控制,对基于电流变液的单一自由度机械臂进行半闭环控制系统研究,机械臂系统包括:驱动电机,谐波传动,执行机构和电流变阻尼器.并通过极点配置的方法计算阻尼系统和控制系统参数.通过Matlab平台进行仿真计算可以看出:电流变液作为可变阻尼可明显的抑制共振/反共振的现象.并将这种新型控制系统与传统PD控制系统进行对比分析,可以看出电流变液作为可变粘性阻尼器对抑制干扰和振动起到重要的作用.     

蠕动式压电电流变液进给机构的负位移现象

为研制电流变液作为钳位介质的大行程高精度蠕动式进给机构,以压电陶瓷作为驱动元件,沸石/硅油型电流变液作为钳位介质,研制了蠕动式压电电流变液直线式进给机构样机,并利用计算机编程对机构的进给运动进行了控制,发现机构运动中存在负位移现象并研究了压电陶瓷驱动电压、电流变液钳位电压以及电流变液充放电时间对机构负位移的影响,建立了机构的动力学模型,对影响负位移大小的因素进行了定性探讨。结果表明,机构运动过程中,极板所受的作用力主要是钳位力、阻尼力和压电陶瓷的驱动力,增大钳位力,减小阻尼力,增大驱动力同时减缓驱动力的变化速率,对减小负位移有利。     

压电陶瓷在ER高压电源中的应用研究

电流变(ER)技术现正蓬勃发展，而高压电源却成了发展中的一大障碍。本文从压电陶瓷着眼，简要介绍了它的高压输出特性，以及它较传统变压器的优点。给出了压电陶瓷在ER高压电源中的一些应用研究情况，并提出了其中所存在的一些问题及今后的发展方向。     

复合结构研齿换能器的动力学特性与设计

利用4段复合式变幅杆及夹心式压电陶瓷换能器的结构,研制了一种用于超声辅助研磨弧齿锥齿轮的新型换能器。首先,根据牛顿定律和超声波传输线理论,推导得到了超声研齿换能器的频率方程,依据压电陶瓷的谐振频率、振动模式和输入功率,确定了复合式超声研齿换能器的结构参数;其次,运用等效声学参数修正法和质量互易法,对设计的换能器进行了声学和结构参数的修正;然后,利用ANSYS分析软件进行了模态分析和谐响应分析,对换能器的谐振频率、振动幅度、振动速度比和导纳等动力参数进行了研究;最后,进行了阻抗特性测试和振动特性实验和通过5对弧齿锥齿轮的超声研磨实验,进一步证实了复合结构研齿换能器的超声研磨性能。     

容性负载高压线性驱动电源的研究

介绍一种高压可调大功率动态驱动电源的设计,它用于高速微小孔振动钻床振动装置的压电陶瓷激振器,可以实现压电陶瓷的可控振动,其主要由D/A控制卡、放大电路、高压直流电源电路等几部分组成.该驱动电源具有线性好、容易控制等优点.     

悬臂压电叠层复合梁的弯曲振动固有频率

压电叠层复合梁是一种三叠片对称结构。这里以压电陶瓷-金属-压电陶瓷复合结构为研究对象,给出了悬臂式对称压电复合结构的压电振子弯曲振动共振频率表达式,并建立了相应的有限元模型;计算分析了压电陶瓷-金属复合梁弯曲振动的固有频率值与几何尺寸之间的关系,并与相应的有限元模态分析结果进行了比较。结果表明,两种分析方法得到的压电振子的固有频率值基本符合,计算公式和模型是精确有效的;压电叠层复合梁愈细长则表达式的计算结果愈准确。     

基于电流变效应的车削颤振预报控制技术的研究

将电流变减振技术引入机床切削系统,研制了车床横刀架电流变液减振器。通过流变学动态模量测试方法,求得了该系统的附加阻尼和附加刚度,并对该系统振动响应特性进行了理论分析。研制开发了基于电流变效应的车削颤振预报控制系统。预报控制试验结果表明,利用该系统可以对机床切削颤振实施有效的预报控制。     

A non-invasive airborne wave monitor

This work presents a new acoustical method for remote measurement of the surface characteristics of the dynamic air–water interface in turbulent free-surface flows. The technique uses the reflection of a monochromatic ultrasonic wave by the dynamically rough air–water interface to measure the water surface position. It is found that with careful selection of the acoustical components and their configuration, the phase of the reflected signal responds to the local fluctuations in the fluid interface at the point of specular acoustic reflection. In order for the method to be applicable, three criteria must be satisfied: (1) the dominant wavelength of the surface under investigation must be greater than the first Fresnel zone corresponding to the wavelength and component geometry of the acoustical system; (2) the mean magnitude of the instantaneous local surface gradient must not exceed 0.025; and (3) the root-mean-square wave height must be greater than 1% of the acoustic wavelength. Under these conditions the mean error of the system is within 5% (and usually within 1%) of the acoustic wavelength, and is generally within 10% of the wave amplitude for turbulence generated waves, and 3% of the amplitude for gravity waves. This error may be reduced by optimising the acoustic wavelength for the surface of interest. For turbulent depth limited flows, the surface waves fall well within the criteria, and the absolute errors are independent of wave height, so for larger wave heights, the relative error can be considerably lower. The technique provides a robust system for monitoring the dynamics of free surface flows, which is non-invasive, low cost, and low power. The method has been tested on laboratory flows but should be applicable to remote sensing of free surface properties on a local scale in field environments where invasive techniques are difficult to implement such as might be found in coastal, river and wastewater environments.     

Propagation behavior of SH waves in layered piezoelectric plates

In this study, the propagation of SH waves in a coupled plate consisting of a piezoelectric layer and an elastic layer is analytically investigated. The piezoelectric material is polarized in the z-axis direction and perfectly bonded to an elastic layer. The mathematical model of the SH wave propagation in this plate is based on the type of surface wave solution. Dispersion relations with respect to phase velocity are obtained for electrically open and mechanically free. Numerical examples are provided to illustrate graphically and compare the variations of the phase and group velocities versus the wave number for the different layers. The thickness ratio and the properties of the two layers have a significant effect on the propagation of SH waves. The conclusions are meaningful both theoretically and practically for the design of high-performance surface acoustic wave (SAW) devices.     

圆筒型非接触式压电作动器的设计与试验研究

 提出了一种基于超声悬浮和驱动的非接触式压电作动器,该作动器中的转子呈完全悬浮状态。转子的悬浮由兰杰文换能器提供,自身旋转与定位由圆筒型定子提供。通过分别对换能器和定子的压电陶瓷片施加电压,使得换能器悬浮端面激发出一阶弯曲振动模态,而定子激发出两相B(0,3)驻波并合成一高声强行波,进而诱发高声强声场来驱动转子。分别建立了非接触式压电作动器中兰杰文换能器和定子的有限元模型,对换能器和定子进行了分析、设计、扫频以及定频试验,确定了结构方案, 最后加工、制造了样机。搭建了整个样机的测试系统,对其悬浮和驱动特性进行了分析,测得转子转速可达4261r/min。结果表明转子在近声场的作用下成功地实现了完全悬浮式的高速旋转。      

线聚焦无镜头式聚偏氟乙烯超声探头的研制及V(f,z)分析法在表面波波速测量中的应用

线聚焦式超声材料性质表征系统可以对水浸试样漏表面波或类漏表面波的相速度进行精确的测量,但鉴于传统超声显微镜镜头的材料昂贵且制作困难,采用厚度为40 μm的聚偏氟乙烯(Polyvinylidene fluoride,PVDF)压电薄膜作为激励/接收元件,设计、制作两个应用于声学显微系统的线聚焦无镜头式PVDF超声换能器,...     

Effect of Structural Parameters of a Transducer on the Duration of an Acoustic Pulse Transmitted into a Solid

A damped piezoelectric plate loaded with a solid medium (steel) through a contact layer/wear face/contact layer system is considered. The piezoelectric plate is excited by an electric pulse in the form of a sine half-period at the frequency of thickness vibrations. The duration and amplitude of pulses of the vibrational velocity as functions of the parameters (specific acoustic impedances and wave thicknesses) of transition layers are studied by calculations.     

超声波液体传送装置的设计

提出了一种行波型超声液体传送装置,其传送机理是利用纵向振动的超声波换能器激起传送管上的弯曲行波,使输送管管壁质点产生椭圆运动从而在液体中产生声流来驱动液体运动。从理论上证明了超声波液体传送装置中行波和声流的存在,并建立了有限元模型。该装置具有结构简单、响应迅速和噪声小等特点。     

旋转型压电行波超声马达的驱动与控制技术

压电行波超声马达是一种由高科技发展起来的全新概念产品，它利用压电陶瓷的逆压电效应和超声振动，将定子的微观变形通过共振放大和界面摩擦，转换成转子的宏观运动。     

Optimum cut orientation of piezoelectric substrate and propagation direction of SAW for rotation rate sensor

The effect of Coriolis and centrifugal forces on the propagation characteristics of surface acoustic waves (SAW) on a rotating piezoelectric substrate can be utilized for sensing rotation rate. In this paper, the relationship between SAW phase velocity and the rotation rate of the substrate is analyzed theoretically and numerically based on the coupling wave equations on anisotropic piezoelectric substrate with rotation effect. Partial wave theory and surface effective permittivity method are employed. Using LiNbO₃ as an example, some quantitative results of SAW rotation rate sensor, including free and metalized interfaces between substrate and free space in X-cuts, Y-cuts, and Z-cuts, are obtained. Furthermore, by considering comprehensively SAW rotation rate sensitivity with SAW excitation efficiency and beam steering, the optimum cut orientation of piezoelectric substrate and propagation direction of SAW for rotation rate sensor are presented. The research findings can provide theoretical guidance and simulation basis for the experimental research on SAW rotation rate sensor.     

基于阻抗模型的不确定环境下微纳操作力跟踪控制策略研究

微机电系统在生物医学领域具有巨大的应用潜力，以压电陶瓷为基础设计的压电驱动系统在微纳操作高精度控制领域发挥着重要作用。在各领域的实际应用中，微操系统与环境的交互一直是研究的热门方向。由于微尺度下跟踪力误差相比宏观尺度下更不可忽略，因此微操作臂与环境接触力的精准控制是提高微操作准确度的关键。为此本文提出一种力跟踪阻抗控制策略，能够在操作过程中实现对接触力的精确跟踪。考虑到阻抗模型对环境参数要求较高，本文提出了扩展卡尔曼滤波器对外部环境参数进行在线估计的方法。实验结果表明，所提控制方法能够成功实现微操作臂-环境交互模型的力跟踪控制并且有良好的跟踪精度，力跟踪平均绝对误差为7.82 mN,均方根误差为10.16 mN,因此该方法对不确定性环境下接触力的精确跟踪具有可行性。