泵用压电振子动态特性的研究

为了提高压电泵的效率、优化压电泵的结构,对泵用压电振子的动态特性进行了研究。介绍了一种新型压电泵——Y形流管无阀压电泵的结构和工作原理;对Y形流管无阀压电泵压电振子的振动状态进行了理论分析,得到了压电振子的固有频率及最大振幅的理论计算公式,并证明了理论分析结果的正确性;根据理论分析结果,对压电振子几何参数和基底层材料对其振动特性的影响进行了分析讨论。分析结果表明：压电振子的PZT层与基底层的直径比应在0.75左右,厚度比应小于1;基底层材料对频率影响较大,但对最大振幅影响较小。     

Spectral element modeling and analysis of the dynamics and guided waves in a smart beam with a surface-bonded PZT layer

To predict ultrasonic guided waves generated by a piezoelectric transducer (PZT) in a structure accurately, the dynamic coupling between the base structure and the surface-bonded PZT must be modeled accurately and analyzed in an efficient way. For so-called smart beams, which consist of a metallic base beam and a surface-bonded PZT layer, we propose a spectral element model that has the capability to accurately predict high frequency dynamic responses and guided waves. For the spectral element model, Timoshenko beam theory is applied to both the base beam and PZT layer, and Mindlin-Herrmann rod theory is adopted to account for the effects of lateral contraction in the thickness direction of the base beam. The high accuracy of the spectral element model is validated by comparing the results of the spectral element model with conventional finite element method (FEM) results and results from the commercial finite element analysis package ANSYS. The effects of PZT-induced axial-bending coupling and structural damping on the dynamics and guided waves are then investigated using numeral simulation.     

压电智能悬臂梁的压电片位置、尺寸及控制融合优化设计

对压电智能悬臂梁振动控制中的压电片的位置、尺寸及其控制参数进行研究.在对压电片和基板的耦合特性进行分析的基础上,建立智能悬臂梁的压电传感、致动方程及基于闭环控制系统的状态方程,并以系统的存留能量作为目标函数,建立压电智能悬臂梁压电片的位置、尺寸和控制参数的优化模型及一阶灵敏度分析表达式,并采用移动渐进线法(Method of moving asymptotes,MMA)对模型进行求解.采用Simulink对优化结果的动态响应特性进行仿真分析,仿真结果表明,采用提出的优化模型及算法对悬臂梁压电片的位置、尺寸和控制参数进行优化是合理的.     

一种新型PZT压薄膜应力传感器的设计仿真

针对目前应力传感器不能兼顾柔性、动态测量及无法测量曲面接触应力特征信息等难题,设计了一种新型的PZT压电薄膜柔性应力传感器。主要有由PZT压电薄膜、导线、特殊的压敏涂层等构成。传感器的受力信息可以通过检测PZT压电薄膜传感器的电荷变化来获取,可应用于测量各种接触面之间的应力。为研究测量轮胎路面等具有复杂曲面接触结构的应力分布提供了新的思路和方法,分析了压电传式感器的工作原理,压电薄膜的传感特性,建立有限元分析模型,进行仿真分析,结果表明该传感器结构简单、体积小,相对于传统测量方法更加可靠,适用于曲面应力的测量。     

Dynamic analysis of smart composite beams by using the frequency-domain spectral element method

To excite or measure the dynamic responses of a laminated composite structure for the active controls of vibrations or noises, wafer-type piezoelectric transducers are often bonded on the surface of the composite structure to form a multi-layer smart composite structure. Thus, for such smart composite structures, it is very important to develop and use a very reliable mathematical and/or computational model for predicting accurate dynamic characteristics. In this paper, the axial-bending coupled equations of motion and boundary conditions are derived for two-layer smart composite beams by using the Hamilton??s principle with Lagrange multipliers. The spectral element model is then formulated in the frequency domain by using the variation approach. Through some numerical examples, the extremely high accuracy of the present spectral element model is verified by comparing with the solutions by the conventional finite element model provided in this paper. The effects of the lay-up of composite laminates and surface-bonded wafer-type piezoelectric (PZT) layer on the dynamics and wave characteristics of smart composite beams are investigated. The effective constraint forces at the interface between the base beam and PZT layer are also investigated via Lagrange multipliers.     

Prediction of residual stress distribution in multi-stacked thin film by curvature measurement and iterative FEA

In this study, residual stress distribution in multi-stacked film by MEMS (Micro-Electro Mechanical System) process is predicted using Finite Element method FEMi. We develop a finite element program for residual stress analysis (RESA) in multi-stacked film. The RESA predicts the distribution of residual stress field in multi-stacked film. Curvatures of multistacked film and single layers which consist of the multi-stacked film are used as the input to the RESA. To measure those curvatures is easier than to measure a distribution of residual stress. To verify the RESA. mean stresses and stress gradients of single and multilayers are measured. The mean stresses are calculated from curvatures of deposited wafer by using Stoney’s equation. The stress gradients are calculated from the vertical deflection at the end of cantilever beam. To measure the mean stress of each layer in multi-stacked film, we measure the curvature of wafer with the left film after etching layer by layer in multi-stacked film.     

硅基PZT压电功能结构研究

PZT压电薄（厚）膜是制备MEMS传感元件和执行元件重要的功能材料,对近年PZT薄（厚）膜在MEMS领域的研究现状进行了分析,提出了一种新型的双杯PZT/Si膜片式功能结构;采用有限元方法对双杯PZT/Si膜片进行了结构优化,得到PZT和上、下硅杯的结构优化值为DPZT: D1:D2 =0.75:1.1:1;一阶模态谐振频率为13.2KHz;以氧化、双面光刻、各向异性刻蚀,以及PZT厚膜丝网印刷等工艺技术制作了双杯硅基PZT压电厚膜膜片,该膜片具有压电驱动功能。双杯PZT/Si膜片式功能结构的MEMS技术兼容性好,对芯片内其它元件或电路的影响小,适合作为MEMS片内执行元件的驱动机构。     

“Y”形流管无阀压电泵驱动器的动态研究

为满足输血或输液工作需求而特别设计了一种新型"Y"形流管无阀压电泵,研究了它的驱动器--压电驱动器的工作特性.理论分析了驱动器的动态特性,并推导出其固有频率和最大振幅的计算公式.然后,验证了理论分析的正确性.最后,基于理论模型,对驱动器的几何参数和材料特性对其动态性能的影响进行分析讨论.分析结果表明,压电陶瓷层与基底层的半径比应为0.75左右,厚度比应<1.0.本研究亦为其他类型压电泵的优化设计和制作提供了实用性的参考.     

一种新型压电驱动开关阀的理论设计

数字液压在节能、可靠性、控制性能等方面较传统液压控制方法有巨大优势,高速开关阀作为数字液压中的关键部件,其研究近年来得到重视。设计了一种新型压电驱动开关阀,采用基于三角放大原理的滚针结构,对压电材料的输出位移进行放大,用于阀芯驱动。由于位移放大机构会导致输出力相应减小,传动后的驱动力难以克服静态液压力,设计了等径分离的阀芯结构来平衡液压力。理论分析和仿真结果表明,压电放大机构满足设计阀芯行程要求,且阀芯结构能有效减少静态液压力,符合提出的期望参数。     

基于激光多普勒技术的PZT薄膜压电性能测试研究

应用基于激光多普勒技术的微小形变分析方法,并引入数字锁相技术,成功实现了PZT(Pb(Zr,Ti)O₃)铁电薄膜的压电性能测试。对商用压电陶瓷在小信号激励下的压电性能测试表明,数字锁相技术的引入能有效抑制系统噪声,并提高激光多普勒系统的位移检测分辨率,使其达到皮米量级。此外,研究了用溶胶-凝胶技术和溶胶-电雾化技术制备得到的PZT薄膜的电压-位移曲线和压电位移"蝴蝶线",实验结果表明:在5 V直流偏置下测得两种方法制备得到的PZT薄膜的d₃₃压电系数分别为218.7 pC/N和215.8 pC/N,相应的标准偏差分别为12.7和28.6。     

基于阻抗技术的压电元件自损伤检测-

为了保证结构健康监测系统的有效运行,基于压电阻抗技术原理,提出了一种压电传感、驱动元件自损伤检测方法.通过研究压电元件等效电容值(压电元件导纳虚部数值)的变化,判别压电元件是否破损及其与主体结构之间是否剥离,并在悬臂梁结构上进行压电元件自损伤检测试验.结果表明,相比压电元件完好的情况,各频率下压电元件电纳值随脱粘部分面积的增加而上升,随破裂部分面积的增加而下降,并且损伤程度和等效电容变化量成比例关系,与理论分析结果吻合较好.     

载荷影响下的机电阻抗协整结构损伤识别方法

高频机电阻抗(electromechanical impedance, 简称EMI)方法利用粘贴在结构表面的压电传感器(piezoelectric transducer, 简称PZT)进行主动激励,通过连续监测和分析PZT机电导纳信号的变化评估结构的健康状态;然而EMI方法容易受到环境工况变化的影响,导致结构损伤的误报。针对此问题,采用时间序列协整方法处理及消除结构工作载荷对阻抗谱特征信号的影响。该方法是基于结构动荷载作用下PZT阻抗谱导纳信号的非平稳特征,将动荷载影响下的阻抗谱非平稳时间序列经线性组合变换成平稳时间序列,根据得到的协整余量序列有效判断结构的健康状态。为验证该方法的有效性,开展了动应力影响下铝梁结构的螺栓松动损伤识别实验。结果表明,协整消除了动态应力对EMI方法的影响,当铝梁内存在持续变化的应力时,仍可以准确识别螺栓松动。机电阻抗协整方法能够消除结构健康监测中荷载作用的影响,及时准确地进行结构损伤识别。     

Prediction of actuating displacement in a piezoelectric composite actuator with a thin sandwiched PZT plate by a finite element simulation

This paper presents the evaluation of a plate-type piezoelectric composite actuator (PCA) with a thin sandwiched plate having four kinds of lay-up configurations by analyzing the flexural displacement For this, a three-dimensional finite element simulation considering the thermal deformation effect of PCA during manufacturing is conducted based on a thermal analogy model. The distribution of residual thermal stresses and the dome height caused by the mismatch in coefficient of thermal expansion (CTE) between the layers of PCA are predicted with the aid of a classical laminated plate theory (CLPT). Results of finite element analyses have revealed that the flexural displacement of PCA subjected to electric fields is considerably affected by the variation of lay-up configuration, the thickness of an embedded PZT wafer and boundary conditions. In particular, as the thickness of the PZT ceramic increases, the bending stiffhess of PCA increases faster than the actuation distance does, which leads to the overall reduction in flexural displacement. It is therefore suggested that the electrically induced flexural displacement of unimorph-type PCA depends more on the bending stiffhess than on the actuation distance.     

Ansys在PZT压电薄膜微传感器压电分析中的应用

研究的PZT压电薄膜微传感器采用的弹性敏感元件为微悬臂梁结构,在压电原理和材料力学理论的基础上,采用简化的等效微器件结构建立了数学分析模型,将有限元方法发展应用于压电材料的结构分析中,并运用有限元软件Ansys7.0对PZT压电薄膜微悬臂梁结构的传感性能和线性度进行了模拟,同时分析了微悬臂梁结构的几何参数对输出电压的影响,这些分析结果和解析预测是一致的。     

Characterization of lead zirconate titanate--lanthanum ruthenate thin film structures prepared by chemical solution deposition

In this work, the results of compositional and microstructural analysis of lead zirconate titanate--lanthanum ruthenate thin film structures prepared by chemical solution deposition are discussed. The cross-section transmission electron microscope (TEM) micrographs of the La-Ru-O film deposited on a SiO2/Si substrate and annealed at 700 degrees C revealed RuO2 crystals embedded in a glassy silicate matrix. When the La-Ru-O film was deposited on a Pt/TiO2/SiO2/Si substrate, RuO2 and La4Ru6O19 crystallized after annealing at 700 degrees C. After firing at 550 degrees C randomly oriented lead zirconate titanate (PZT) thin films crystallized on the La-Ru-O/SiO2/Si substrate, while on La-Ru-O/Pt/TiO2/SiO2/Si substrates PZT thin films with (111) preferred orientation were obtained. No diffusion of the Ru atoms in the PZT film was found. Ferroelectric response of PZT thin films on these substrates is shown in comparison with the PZT film deposited directly on the Pt/TiO2/SiO2/Si substrate without a La-Ru-O layer.     

Modeling and analysis of curved beams with debonded piezoelectric sensor/actuator patches

In this paper, a mathematical model for thin-walled curved beams with partially debonded piezoelectric actuator/sensor patches is presented for investigating the effect of debonding of the actuator/sensor on their open- and closed-loop behaviors. The actuator equations and the sensor equations of the curved beam in perfectly bonded and debonded regions are derived. In the perfect bonding region, the adhesive layer is modeled to carry constant peel and shear stresses; while in the debonding area, it is assumed that there is no peel and shear stress transfer between the host beam and the piezoelectric layer. Both displacement continuity and force equilibrium conditions are imposed at the interfaces between the bonded and debonded regions. Based on the model and the sensing equation of the sensor, a closed-loop vibration control for the curved beams is performed. To obtain the frequency response from the presented model, a solution scheme for solving the complex governing equations is given. Using this model and the solution scheme, the effects of the debonding of actuator and sensor patches on open- and closed-loop control are investigated through an example. The results show that edge debonding of the piezoelectric patch has a significant side effect on the closed-loop control of the curved beams.     

GMM/PZT/GMM层合材料的纵振磁电响应

层状复合结构层间胶层和复合材料的机械损耗是影响层状磁电复合材料磁电响应的重要因素.为了考虑层间胶层的作用,包括其纵向变形和剪切变形产生的效果,应用Hamilton原理建立层状复合结构的运动方程,并用复柔顺系数来反映材料的机械损耗特性.结合层状复合结构的边界条件和磁致伸缩/压电本构方程,就可以得到考虑了胶层作用和材料损耗时,复合结构的固有频率和磁电响应.对GMM(超磁致伸缩材料)/PZT(压电材料)/GMM结构的磁电响应进行了数值计算,将计算结果与实验结果进行了比较,证明考虑胶层作用并引入材料的损耗能够更准确预测复合材料的磁电换能特性.     

Vibration control efficiency of piezoelectric shunt damping system

The piezoelectric shunt damping technique based on the direct piezoelectric effect has been known as a simple, low-lost, lightweight, and easy to implement method for passive damping control of structural vibration. In this technique, a piezoelectric material is used to transform mechanical energy to electrical energy. When applying the piezoelectric shunt damping technique to passively control structural vibration, the piezoelectric materials must be bonded on or embedded in host structure where large strain is induced during vibration, thus to ensure vibrational mechanical energy to be transformed into electrical energy as much as possible. In this paper, the concept of vibration control efficiency of a piezoelectric shunt damping system is proposed and studied theoretically and experimentally. In the study, PZT patches are used as energy converter, and the vibration control efficiency is expressed by the vibration reduction rate per area of the PZT patches. Emphasis is laid on the effect of the generalized electromechanical coupling coefficient K₃₁ on the vibration control efficiency. Four PZT patches with different sizes are bonded on the geometrical central area of four similar clamped aluminum plates, respectively, and vibration control experiments are conducted for these plates using the R-L shunt circuit. The results indicate that the bigger the coupling coefficient K₃₁, the larger the rate of vibration reduction, and hence, the higher the vibration control efficiency. It also shows that the vibration responses of the first mode of the plates bonded with different PZT patches can be reduced by about 30.5%，48.58%，85.47%, and 89.91%, respectively. It comes to a conclusion that the vibration control efficiency of the piezoelectric shunt damping system decreases with the increase of the area of the PZT patch, whereas the vibration reduction of the plate increases with the area of the PZT patch. Therefore, it is necessary to make topology optimization for the PZT patch in the vibration control utilizing the piezoelectric shunt damping technique.     

压电智能梁的拉伸—弯曲耦合模型

利用力平衡原理,建立了单面粘贴有压电致动器的梁结构的拉伸—弯曲耦合模型,在分析过程中,考虑了梁与致动器之间粘贴层的影响。通过分析可得,粘贴层切应力的分布与致动器端部附近的应变分布有相似的特征,随着粘贴层的切变模量的增加或其厚度的减小,切应力在靠近压电致动器端部区域迅速增大。     

压电智能梁的静态耦合模型

利用力平衡原理，建立了单面粘贴有压电致动器的梁结构的静态拉伸－弯曲耦合模型，在分析过程中，考虑了梁与致动器之间粘贴层的影响。通过分析可得，粘贴层剪切应力的分布与致动器端部附近的应变分布有相似的特征。随着粘贴层的剪切模量的增加或其厚度的减小，剪切力在靠近压电致动器端部区域迅速增大。