静电驱动振模微泵的理论分析

利用最小能量法和均匀压力载荷下的圆薄膜大变形半解析解相结合的方法,改进了静电驱动柔性振膜微泵的理论分析模型.计算结果表明:考虑圆薄膜的周向应变,利用均匀压力载荷下的圆薄膜大变形半解析解来预测振膜的形状,对微泵的性能有显著的影响,证明了圆薄膜大变形时的周向应变是不可忽略的.同时讨论了介电层厚度、腔体形状和双腔结构对微泵压缩性能的影响.结果表明:采用双腔结构,减小介电层厚度、减小腔体深度、缩小腔体半径,对静电驱动柔性振膜型微泵性能的提高具有积极意义.     

磁能驱动微型泵的性能实验研究

在电磁场驱动原理的基础上,设计并研制了一种磁能驱动的微型泵。微型泵包括进／出液管、扩散管／喷管、驱动薄膜、腔体、电磁线圈和永磁体。微型泵的整体尺寸约为Ф11mm×4mm,腔室半径为5mm,深2mm。利用正交实验方法,对微型泵的性能进行了测试。在电压为4V、驱动薄膜厚度为6μm、频率为5Hz方波脉冲的最佳实验条件下,微型泵的最大泵送流速约为0．21mL／min。     

微小型静电泵的设计(1)

介绍了微小型静电泵工作原理,分析了上腔充压的静电泵阀腔的形状与结构、所加激励电压、可动薄膜面积与厚度对泵的压力、流量、受力和变形的影响,提出了一套完整的数据图标和表格,例如激励敏感膜片的绕度及相应鼓起的体积、膜上所承担压力及其所受的径向应力与泵的半径和膜厚的关系图、表,以便选用.     

磁力驱动串联式双腔微泵设计及性能测试

针对无阀微泵背压能力较弱等问题,采用MEMS技术制作出不同结构参数的双腔和单腔微泵体,构建了基于电机驱动的磁力式双腔串联无阀微泵测控系统.实验结果表明,泵腔面积相等的情况下,圆形泵腔的微泵流量大于椭圆形泵腔的流量;随着驱动频率的升高,双腔串联微泵的流量呈现高斯分布,并在20 Hz附近处出现流量峰值,微泵的最大流量可达1.5 mL/min,微泵的截止背压为170 mmH2O,双腔串联微泵比单腔微泵的流量增大约80％.     

磁力驱动微泵设计及优化

为提高收缩/扩散管无阀微泵的性能,设计了磁力驱动式无阀微泵,并利用ANSYS软件对微泵的整流部件收缩/扩散管和单腔微泵整体结构进行流体仿真,得到了微泵的结构优化参数.仿真和实验结果表明,流量随着管长、最小宽度、扩张角、泵腔半径的增大存在极大值.磁驱动微泵的流量在驱动电压12 V、驱动频率为25 Hz时达到最大值.     

微小型静电泵的设计(2)

推导出作用于激励膜片上的静电抽压力与微型静电泵极板间所加电场强度、电压及泵的半径、上腔高度的关系公式,并绘制出相应图、表以便选用.因为泵的静电抽压力与上腔高度有关,因此针对膜鼓起时,膜与泵顶距离增加导致静电抽力存在偏差,对静电抽力进行了修正,提出了有效上腔高度的概念,把膜鼓起后增加的体积迭加到基础上腔体积上,然后把它看成是一个以泵底面,有效上腔高度为高的整体圆柱体,再来近似计算圆柱体极板间静电抽压力,并举例介绍了修正计算过程.     

串联压电微泵特性研究

介绍了一种压电驱动的串联无阀微泵.基于收缩管/扩展管整流特性的分析,建立了微泵输出特性的表达公式.采用有限元仿真软件ANSYS对微泵内流体的流动过成进行了数值模拟,结果显示,在相同的驱动条件下,串联无阀微泵的工作性能优于单腔无阀微泵的工作性能.泵流量随着驱动电压的增加而增加.当固定的驱动电压下,存在最优的压电层厚度使得泵流量最大.研究结果为串联微泵的优化设计提供了依据.     

微圆顶结构柔性触觉传感器接触模型与仿真研究

面向高灵敏度柔性触觉传感器应用需求,研究微结构在高灵敏柔性触觉传感器制备中应用。依据压阻理论和接触力学,建立微圆顶结构数学接触模型,并结合ANSYS有限元仿真,论述柔性触觉敏感单元微圆顶接触半径与外力之间的函数关系,揭示微圆顶结构几何参数对压阻特性的影响,阐述微圆顶结构柔性触觉传感器更有利于提升传感器灵敏度和线性度,为高灵敏度柔性触觉传感器设计提供参考依据。     

MEMS密闭腔内微气流的挤压膜阻尼效应研究

针对MEMS密闭腔内微气流与压电驱动机构的耦合振动,综合采用空气挤压膜阻尼效应和能量法进行理论分析。根据等温雷诺方程求解气体压力分布,进而计算微气流挤压膜阻尼能,将其代入能量方程,与压电-硅膜的耦合动能、势能、压电电场能进行能量耦合,将由能量方程确定的压电-硅膜-微气流耦合作用下的位移振形待定系数λ′与无气流影响下的压电-硅膜耦合振动位移振形待定系数λ对比后,找到了增加的阻尼项,微气流对驱动结构振动位移的影响正是通过该阻尼项体现的。研究可为微流体的驱动及协调控制提供相关理论基础及控制策略。     

基于MEMS技术的F-P腔滤波器分析与设计

通过对微光纤法布里—珀罗(F-P)腔滤波器工作原理的综合分析,确立了微F-P腔滤波器静电驱动腔长调谐方案.对可调谐滤波器的主体部分进行光学设计和分析,确立了反射镜的多层薄膜光学结构,并借助ANSYS有限元力电耦合分析,最终选择L型桥臂支撑的腔体结构,可以实现0.625μm的调谐范围;保持桥面平行的能力很高,可实现高精度的滤波效果;结构稳固,能够抵抗制造时的残余应力.     

Analytical model of electrostatic actuators for micro gas pumps

We analytically predict the performance of electrostatic actuators for diaphragm micro gas pumps by combining energy minimization and the analytical solution for membrane deformation under uniform pressure. The tangential strain of the membrane is considered in the calculation of membrane deflection. Models for both single- and double-cavity pumps are established to define the restriction of the upper cavity on the membrane during actuation. The shape lines of the membrane in a double-cavity structure are demonstrated under different voltages. The influence of dielectric thickness and cavity geometry on pumping consequence is also discussed. In accordance with other simulation results on diaphragm displacement and chamber pressure rise, an electrostatic diaphragm micro gas pump with a relatively thin dielectric layer and a cavity of comparatively small depth and radius suitably generates high pressure rise. Furthermore, a double-cavity structure enhances pressure rise for the restriction of the upper cavity on the membrane during deformation.     

Analytical model of electrostatic actuators for micro gas pumps

We analytically predict the performance of electrostatic actuators for diaphragm micro gas pumps by combining energy minimization and the analytical solution for membrane deformation under uniform pressure. The tangential strain of the membrane is considered in the calculation of membrane deflection. Models for both single- and double-cavity pumps are established to define the restriction of the upper cavity on the membrane during actuation. The shape lines of the membrane in a double-cavity structure are demonstrated under different voltages. The influence of dielectric thickness and cavity geometry on pumping consequence is also discussed. In accordance with other simulation results on diaphragm displacement and chamber pressure rise, an electrostatic diaphragm micro gas pump with a relatively thin dielectric layer and a cavity of comparatively small depth and radius suitably generates high pressure rise. Furthermore, a double-cavity structure enhances pressure rise for the restriction of the upper cavity on the membrane during deformation.

     

Study on a piezohydraulic pump for linear actuators

To obtain high flowrate and pressure, a piezostack pump with stiffened chamber diaphragm (consisting of a membrane and rigid disk) was presented and studied. An analytical model for performance evaluation is established based on the theory of plate and shells. The effect of chamber diaphragm parameters on flowrate, pressure and output energy coefficient, and that of external load on flowrate and output energy coefficient were analyzed. Considering the influence of the diaphragm stiffness on dynamic–response performance of the piezostack actuator, the design method was introduced. Analysis results show that all of the flowrate, backpressure and output energy coefficient increase with the decreasing of membrane thickness. There is an optimal radius ratio (rigid-disk radius to membrane radius) for flowrate and pressure to achieve peak value, which decreases with the raising of the membrane thickness. On the other hand, output energy coefficient, which decreases with the increasing of radius ratio, achieves peak when force ratio (external load to blocked force of piezostack) is 0.5. At stiffness match and optimal load, maximal output energy coefficient is independent of membrane thickness, and flowrate decreases with the increasing of membrane thickness. To examine analytical results, a check-valve piezostack pump was fabricated and tested. The experiment results show that the flowrate can be enhanced with optimizing rigid disk.     

Capacitive flexible pressure sensor: microfabrication process and experimental characterization

Kapton-based flexible pressure sensor arrays are fabricated using a new technology of film transfer. The sensors are dedicated to the non-invasive measurement of pressure/force in robotic, sport and medical applications. The sensors are of a capacitive type, and composed of two millimetric copper electrodes, separated by a polydimethylsiloxane (PDMS) deformable dielectric layer. On the flexible arrays, a very small curvature radius is possible without any damage to the sensors. The realized sensors are characterized in terms of fabrication quality. The inhomogeneity of the load free capacitances obtained in the same array is ±7 %. The fabrication process, which requires 14 fabrication steps, is accurate and reproducible: a 100 % transfer yield was obtained for the fabrication of 5 wafers gathering 4 sensor arrays each (215 elementary sensors). In the preliminary electro-mechanical characterization, a sensor (with a PDMS dielectric layer of 660 μm thickness and a free load capacitance of 480 fF) undergoes a capacitance change of 17 % under a 300 kPa normal stress.     

介电弹性体驱动系统建模及控制方法综述

介电弹性体驱动系统是一种基于介电材料的形变特性来驱动机械系统的新型柔性驱动装置,利用介电弹性体驱动与控制机器人成为当前软体机器人领域的研究热点.鉴于此,围绕介电弹性体驱动系统的核心关键问题,即驱动系统的建模与控制方法进行全面回顾与展望.首先,阐述介电弹性体驱动系统的结构与驱动过程,对介电弹性体驱动原理进行详细介绍;然后,针对介电弹性体驱动系统所展现出的复杂非线性特性,从建模与控制两个方面展开综述,详细分析不同建模方法与控制策略的优势与局限性;最后,探讨介电弹性体建模和控制中存在的问题及未来的研究方向.     

具有一维带限Weierstrass分形特征实际路面电磁散射FDTD研究

一般的实际路面系统是由沥青混凝土面层、水泥碎石联结层、水泥稳定碎石基层和路基层等构成的多层介质,可以看作是具有一维带限Weierstrass分形特征的水泥混凝土路面系统。运用时域有限差分方法(FDTD)研究了这种实际的水泥混凝土路面系统电磁散射,具体计算了3层路面系统电磁散射的双站散射系数,得出了散射系数随散射角和入射波频率变化的曲线。分析了散射系数随路面分维数、入射波频率、入射角、路面材料介电常数、面层厚度、基层厚度等参数变化的规律,讨论了面层存在圆柱形空洞时,空洞内填充物变化对散射系数的影响,得到了具有一维带限Weierstrass分形特征的实际路面系统电磁散射的特性。数值计算结果表明:路面分维数、入射波频率、入射角、路面材料介电常数、面层厚度、基层厚度、面层存在的空洞对散射系数的影响是非常复杂的。     

应用改进最小距离分类法识别泵功图工况

最小距离分类法广泛应用于文字,图像识别领域。泵功图是封闭的二值曲线图像,可用于判别抽油井各种工况。对最小距离分类法进行改进,并把获得的泵功图进行形态学处理,使之优化为标准功图,然后应用最小距离分类法对油井现场获得的61幅泵功图进行工况分类。实验结果表明,这种方法对泵功图分类是可行的,正确率较高。     

基于路径映射的埋入式压电陶瓷辐射声能特性研究

将压电陶瓷埋入混凝土构成压电埋入式机敏模块能够实现对混凝土结构在线健康监测。为了提高检测的准确性,本文基于路径映射技术对压电陶瓷辐射超声波在混凝土中传输时的声能特性进行研究。研究表明：随着激励频率增大,压电陶瓷辐射声波能量衰减速度减慢,且当激励频率为79 kHz时,更为适合进行压电埋入式超声无损检测实验。随着超声波传播距离增大,扩散范围越广,声压下降速度和声能衰减速率呈非线性变化。在同一激励频率下,不同路径上的最大声压值和最小声压值分别对应不同的位置：当映射路径的半径小于0.08 m时,最大声压值在厚度方向,最小声压值对应的角度在54到58.5之间;当路径的半径大于0.08 m时,最大声压值对应的角度由于厚度方向与径向方向波的部分重叠而偏离轴向处,而最小声压值对应的角度在45°到61°之间。     

Enhanced sensitivity of cancer cell using one dimensional nano composite material coated photonic crystal

We theoretically analyze the detection of a cancer cell in the one-dimensional photonic crystal by infiltrating different sample cells in the cavity layer. The defect modes appear in their transmission spectra only if the nanocomposite layers are included on either side of the cavity layer. This analysis is carried out by a dielectric constant and the transmittance peak of the cancer cell is compared with the normal cell. The transmittance peak shifts are analyzed with various filling factors for optimization purposes. Through the shifting spectrum, the sensitivity of cancer cell from the normal cell is obtained from a minimum of 42 nm/RIU to a maximum of 43 nm/RIU.

     

轴流涡轮转子下游多边界盘腔燃气入侵数值研究

研究涡轮燃气入侵对发动机性能和可靠性具有重要意义,但现有研究多集中于动叶上游盘腔,需要深化对动叶下游盘腔燃气入侵问题的研究。以某高压涡轮及其下游二次空气系统为研究对象,采用三维定常数值模拟探究了适用于转子下游多边界盘腔燃气入侵仿真方法,分析了不同压比下封严流量和燃气入侵特性,并研究了盘腔内部流动机理。结果表明：采用压力边界条件的仿真结果更符合多边界盘腔流动现实。各封严流量随盘腔进口压力增加而增大,但梯度逐渐减小,轮缘封严达到最小流量后基本呈线性变化,而盘腔内部封严流量趋于稳定。在阻止主流入侵的最小封严流量附近,轮缘封严压力分布难以判断主流是否入侵盘腔内部,而轮缘封严齿间流体温度是判断主流燃气入侵盘腔内部的重要参数。