定向BaTiO3晶须/PVDF压电复合材料的制备及性能研究

以高度定向的BaTiO3晶须作为活性相、聚偏氟乙烯(PVDF)作为基体制备了压电复合材料，研究了该复合材料的介电和电学性能，研究结果表明，以BaTiO3作为活性相的晶须复合材料与粉末复合材料相比，其介电常数(ε)、压电常数(d33)和剩余极化率(Pr)大大提高，而其损耗因子(tanδ)具有相反的趋势，对晶须复合材料，沿晶须定向方向的ε、d33和Pr的值比晶须平行方向要高得多，分析了产生这些差别的原因。     

硅基AlN应力和压电极化研究

通过XRD和Raman谱研究了用金属有机化学气相沉积 (MOCVD)的方法在Si( 111)面上生长的AlN薄膜层上的应力和压电极化 ,Raman谱观察到两个声子峰位分别在 619.5cm- 1 (A1 (TO) )和 668.5cm- 1 (E2 (high) )。通过光学声子E2 (high)的频移为 13cm- 1 计算得到AlN薄膜上的双轴压应力为 5 .1GPa ,在z轴方向上和在垂直于z轴方向上的应变分别为εzz=6 7× 10 - 3和εxx=-1 1× 10 - 2 ,产生的压电极化电荷PPE=2 .2 6× 10 - 2 c·m- 2 ,这相当于在Si的表面产生浓度为 1.41× 10 1 3c·cm- 2 的电子积累。同时 ,实验还发现在MOCVD生长过程中存在Si原子的扩散 ,在界面处形成了一个过渡层 ,过渡层主要以Si原子取代Al原子的位置并形成Si-N键为主。     

Perturbation method of the piezoelectric fracture mechanics considering the permittivity of the medium in the crack gap

In this paper, the problem of the cracks with arbitrary forms in piezoelectric material is studied. The permittivity of the medium in the crack gap is considered. Except the collinear cracks, this boundary condition is too difficult to deal with; therefore, a perturbation method is recommended. By the way, the electric boundary conditions of electric fracture mechanics are discussed. For example, a small parameter solution of a crack is given and compared with the known `exact' (it will be discussed later) solution. This result shows that the impermeable or permeable conditions are only the boundary conditions for the first approximations of the perturbation solutions.     

ULTRA‐FINE TRACKING CONTROL ON PIEZOELECTRIC ACTUATED MOTION STAGE USING PIEZOELECTRIC HYSTERETIC MODEL

The tracking control accuracy of the piezoelectric actuator (PEA) is limited due to its inherent hysteresis nonlinearity. A new piezoelectric‐actuator model is synthesized based on two first‐order transfer systems in parallel with two tuned parameters determined from one experiment. Two open‐loop tracking controllers are implemented with the proposed model to compensate the hysteresis of linear positioning. Numerical simulations and experimental tests on the tracking of sinusoidal and triangular waveforms with signal frequencies ranging from 1Hz to 30 Hz are revisited and compared with the conventional Bouc‐Wen and Duhem models. Experimental results reveal that the RMS tracking error can be reduced to less than 2% of the maximum traveling distance without any feedback sensor. When a piezoelectric actuated on a two Degree‐Of‐Freedom (DOF) monolithic motion stage was employed, the RMS tracking error was 50 nm within the measured sensor accuracy.     

损耗测量装置的压电陶瓷线性化设计实现

为了减小测量装置的谐振法测量中由压电陶瓷引入的损耗误差,采用对压电陶瓷驱动信号补偿的办法进行线性化.谐振法测量中需要使用压电陶瓷驱动扫频激光实现损耗检测,压电陶瓷形变非线性会导致模间距T产生误差,损耗值与模间距T成反比,损耗计算中会出现误差,因此压电陶瓷驱动信号需要经过线性化处理,减小在任何位置出的模中的模间距T的误差.实验结果表明:对压电陶瓷进行线性化,使接收到的功率谱信号模间距T的误差从±275(10%)降低至±50(2%),降低了损耗测量误差.     

盘形超声压电振子的抛光实验研究

应用盘形超声压电振子在抛光实验装置上对硅片进行了化学机械抛光,比较了附加行波超声振动的化学机械抛光与传统化学机械抛光的实际效果,实验结果表明,在相同的实验工况下,施加行波超声振动相对于不施加振动,能明显改善硅片化学机械抛光的表面质量。振子振幅的增大对改善硅片表面质量有利。     

功能梯度压电旋转圆环的三维解析解

基于三维压电弹性力学方程,采用直接位移法,给出横观各向同性功能梯度压电旋转圆环的三维解析解.设功能梯度压电材料参数是厚度坐标Z的任意函数,广义位移分量是径向坐标r的幂函数的线性组合,其中含有9个待定的位移函数,它们是坐标Z的函数.结合相应的边界条件,求解控制方程,通过直接积分确定位移函数和相应的积分常数,从而确定旋转圆环的力场和电场.算例展示一种材料的梯度指标对力场和电场的影响.     

STRUCTURE AND PROPERTY OF PIEZOELECTRIC CERAMICS OF QUATERNARY SYSTEM

Composite perovskite piezoelectric ceramicsof PMMN quaternary system were prepared by cold-pressingand solid-phase sintering.Piezoelectric modulus and densityof the samples were measured after polarization.X-raydiffraction analysis and SEM were used to prove the resultthat the major phase of the piezoelectric ceramic spectimenbased on PZT is PZT phase,which is tetragonal system andP_(4mm) space group.     

压电陶瓷与电流变液结合的声学与振动控制系统

通过分别制备高性能压电陶瓷FD3-PZT,FD4-PZT和复合电流变液并测量它们的性能之后,研究和制作了由压电陶瓷与电流变液结合的一种新型声学与振动控制系统(在该系统中的压电陶瓷与电流变液之间连接有一高压延迟电路).当外界施加一个瞬时冲击力作用于该新型声学和振动控制系统中的压电陶瓷上时,压电陶瓷由于压电效应产生瞬时高压(d-c current)输入复合电流变液,电流变液在短时由于其具有的流变性(其电致流变性可逆)而迅速由液态变为固态,从而抵消了外来的瞬时冲击力.该新型声学与振动控制系统在振动控制和声学方面极有应用前景,例如抗(防)次声、声震波和爆炸冲击波的危害以及用于制造高效防弹衣、防护头盔(安全帽)等;在声学方面可制备新型电控激励器、制动器、强振隔离体、无后坐力装备及各种抗震、减振、防噪所需装置等.     

基于压电堆的网壳振动智能控制研究

利用压电材料的压电效应机理,设计出一种压电主控作动杆件,分析其工作原理和设计方法.然后利用模糊智能控制进行仿真,将其应用于网壳结构振动智能控制分析中,结果表明压电主控作动杆可有效地减小结构的加速度和位移响应,为其在桁架结构中的应用打下良好的基础.