基于压电复合材料的二维面阵超声换能器性能研究

采用锆钛酸铅陶瓷基环氧树脂1—3复合压电材料,制作了一种64(8×8)阵元二维面阵超声换能器,并对其进行性能研究.实验测试表明:二维面阵超声换能器一致性良好,回波带宽为40.8％,中心频率为5.0 MHz,与理论设计的3.5 MHz中心频率保持基本一致.对二维面阵超声换能器的声场进行仿真模拟和表征,验证了该超声换能器产...     

一种高频宽带水声换能器的研制

研制了一种宽带、高频压电复合材料圆环阵水声换能器.该换能器的宽带结果是通过采用降低压电材料机械品质因数Qm值和多模耦合振动两种方法实现的.通过径向切割压电陶瓷圆环、灌注环氧树脂得到压电复合材料圆环,再将不同壁厚的压电复合材料圆环轴向叠堆而成敏感元件,对敏感元件进行模具封装,引出电极引线,得到换能器.利用ANSYS软件对结构进行仿真,得到敏感元件谐振频率和带宽随压电陶瓷圆环厚度、高度和平均半径的变化规律,并根据仿真结果确定了换能器敏感元件的最优设计方案.将由最优参数得到的两个压电复合材料圆环轴向叠堆,制作了双圆环叠堆复合材料换能器.经测试,该换能器形成了明显的双模耦合振动,该换能器谐振频率为375 kHz,其-3 dBd工作带宽为90 kHz,最大发送电压响应达148 dB.实现了换能器的高频、宽带、水平全向发射声波的设计目标.     

基于AlN的压电MEMS超声换能器阵列

针对目前超声换能器机电耦合系数较低的问题,本文设计了一种以氮化铝(AlN)为压电材料的微机电系统(MEMS)超声换能器阵列以提高机电耦合系数.在COMSOL Multiphysics中用模态分析确定了超声换能器工作在一阶模态下有最大的声场输出,并给出了其声场传播示意图.通过对超声换能器在工作状态时的应力分析,计算出当上...     

Terfenol-D/PZT和弹性基板阵列换能器的磁电效应研究

利用共振原理,将磁致伸缩材料(Terfenol-D)、压电材料(PZT-8)复合于弹性基板上构造了一种新型的换能器.当激励磁场的频率等于或者接近于弹性基板的固有频率时,Terfenol-D将驱动弹性基板振动并发生共振,粘结于弹性基板上的压电材料的输出电压将达到最大.实验研究表明,在800 Oe偏置磁场和1Oe交变磁场激励下,在谐振点392 kHz处,阵列结构换能器的最大磁电耦合电压系数和最大输出功率分别达到了235.5 mWOe和2.403μW,相比MP层合结构换能器,分别提高了13.77%和33.7%.     

基于PZT的500 MHz超声传感器设计和MEMS制作

利用KLM等效电路模型设计了一种中心频率为478 MHz的超声传感器.采用溶胶-凝胶法在硅衬底上制备了厚度为4μm的锆钛酸铅(PZT)厚膜压电材料,对压电材料的晶体结构、表面剖面形貌、压电性进行了测试,材料均匀致密,具有较好的压电性.研究了超声传感器的制作工艺,制作出实际工作频率为459 MHz的高频超声传感器,搭建测试平台测试其电阻抗,实验值与理论值相匹配,电阻抗误差为1.8％,中心频率误差为3.9％.     

粘接层对PVDF换能器性能影响研究

环氧树脂作为聚偏氟乙烯(PVDF)膜与背衬之间的粘接层将会影响换能器的性能.采用52 μm厚的PVDF压电薄膜制作换能器,以EPO-TEK 301环氧树脂和铜分别作为粘接材料和背衬.通过阻抗分析仪和脉冲回波测试得到PVDF薄膜和换能器的压电性能,并与KLM等效模型的仿真结果进行比较,实验结果与仿真结果基本一致.研究结果表明:随着粘接层厚度的增加,换能器的灵敏度和中心频率将会降低,因此,在PVDF换能器设计制作过程中需合理控制粘接层的厚度.     

GMM 、PZT和超声变幅杆复合结构磁电换能器研究

将超磁致伸缩材料(GMM)、压电材料(PZT-5H)与超声变幅杆复合,构造了一种新型的磁电换能器.超声变幅杆具有聚能和放大应变的功能,可以数十到数百倍增强换能过程中对压电材料的激励,提高机电换能输出和增强磁电耦合效应.实验表明,在800 Oe偏置磁场和峰峰值为1 Oe交变磁场激励下,谐振点处的磁电耦合电压峰峰值达到498 mV,在负载电阻为2.55 kΩ时,输出功率达到4.08 μW.     

硅微压电超声换能器的设计与制作

介绍了一种用ZnO薄膜作为压电层的硅微压电式超声换能器(PMUT).该硅微压电换能器的振动基膜采用LPCVD制作的氮化硅薄膜和PECVD制作的二氧化硅形成的复合振动膜结构.文中运用有限元方法对该硅微压电换能器的结构进行了模拟和计算,并进行了预应力对硅微换能器共振频率的影响的分析.实验测得硅微压电式换能器的共振频率为71.36 kHz.本文还使用该硅微超声换能器在油中进行了初步的共振频率点收发信号的实验,接收实验测得信号峰峰值为9 mV左右,发射实验标准水听器接收信号峰峰值为0.8 mV左右.     

基于DDS技术的低频程控信号源的设计

提出一种基于直接数字频率合成技术，采用芯片AD9850实现的低频程控信号源方案。该信号源可以应用于激振系统，为振动实验和压电加速度计比较法校准的自动化提供一个有效平台。同时，也便于扩展到为超声发生系统提供可控的高频激励信号源。     

基于声表面波技术实现纸基微流开关研究

提出了采用声表面波技术实现纸基微流开关的方法。它由127.68°旋转Y切割X传播方向的LiNbO3压电基片和两个有一定间隙的纸微通道组成。压电基片上采用微电子工艺制作1个中心频率为27.5MHz的叉指换能器和1个反射栅,纸微流通道采用PDMS薄膜贴附于压电基片的声传播路径上,微流通道一侧微流体在没有声表面波作用时,微流...     

Design optimization and sensitivity analysis on buckling stability of piezoelectric truss structures

The design optimization of buckling behavior is studied for piezoelectric intelligent truss structures. First, on the basis of mechanical–electric coupling equation and considering electric load and mechanical loads together, the finite element model of piezoelectric trusses has been built up. Then, the computational formula has been derived for the design sensitivities of critical buckling load factor of the structure with respect to size and shape design variables. The electric voltage is taken as a new kind of design variable and the calculation method of critical load buckling factor with respect to the electric voltage variables is proposed. Particularly, the variations of the loads and pre-buckling inner forces with design variables have been accounted for. Finally, the sequential linear programming algorithm is employed to solve the optimization problem, and a new method of controlling structural buckling stability by optimizing the voltages of piezoelectric active bars is proposed. Numerical examples given in the paper have demonstrated the effectiveness of the methods presented.     

压电扭转驱动器的有限元分析

为研究压电陶瓷的扭转驱动能力,制作了压电扭转驱动器,应用有限元分析方法,使用三维六面体耦合单元对压电扭转驱动器进行了力学和电学分析。根据压电陶瓷的基本方程,利用有限元分析软件ANSYS进行直接耦合分析求解。分析结果与试验结果取得了良好的一致,证实了利用压电陶瓷双晶片弯曲制作压电扭转驱动器结构设计的可行性。该分析方法与结论对压电驱动器的设计、制造与优化具有一定的指导意义。     

主动约束层阻尼梁有限元建模与动态特性研究

基于弹性、粘弹性和压电材料的本构关系,利用Hamilton原理,推导了主动约束层阻尼梁的有限元动力学模型．结合压电材料的机电耦合特性,采用自感电压的位移反馈,研究了主动约束层阻尼梁的闭环控制特性．求解了主动约束层阻尼简支梁的动态特性如固有频率、模态损耗因子及频率响应特性等．对被动控制、主动控制和主被动混合控制的控制效果进行了分析比较．研究了粘弹性层与约束层厚度等参数对减振控制效果的影响．     

微型双稳态板压电俘能器的仿真研究

基于中间固定、四边自由的微型压电层合板模型,应用应变梯度理论考虑其尺寸效应,借助ABAQUS用户自定义子程序(UEL)模块自定义了一种三维八节点的微型压电单元.利用有限元法热-力-电耦合分析对微型双稳态板压电俘能器进行了仿真研究,发现其在不同的激振频率下存在不同的变形状态,非线性动态分析显示该结构在其一阶固有频率之前也能俘获较多电能,且存在多态转换交替出现的现象.针对该微型双稳态压电俘能器,给出了其最佳的工作频率和最大俘获电压.研究成果对微型压电俘能器的设计分析和性能检测具有重要的指导意义.     

Modeling of piezoelectric sensors adhesively bonded on trusses using a mathematical programming approach

In this study, piezoelectric sensors design adhesively bonded on truss elements is treated in the framework of mathematical programming. A numerical formulation based on the strength capacity of set structure, adhesive and piezoelectric sensor is proposed. Inside the formulations maximum strength capacity of the adhesive is considered as a limit value in the design. Two formulations are established to obtain the maximum strength of the set; the first one is built on the basis of finite differences and the other one on a formulation of finite elements both based on an admissible static field. The lower bound method applied to limit analysis is extended in this research to analyze trusses with sensors including the adhesive interface. Four examples are designed to assess the numerical methodologies in which the results are compared with other known data. The main contribution of this work is focused on finding the maximum coupling load that a piezoelectric sensor can read before being debonded based on the minimum size constraint of the sensor.     

On the performance of 1–3 piezoelectric composites with a passive and active matrix

Piezoelectric composites with 1–3 connectivity are an important class of materials for underwater acoustics and biomedical imaging. Their dependence on the electromechanical properties and geometry of the piezoelectric fibers creates an opportunity for tailoring its performance according to the design requirements. In this research, the performance of 1–3 piezoelectric composite with an active and passive matrix is studied. The micromechanics based Mori-Tanaka model for piezoelectric composite is used to determine the electromechanical moduli of the composites. In comparison with a passive polymer matrix, the use of active polymer matrix can significantly enhance the hydrostatic performance of the piezoelectric composite. However, no significant improvement on the electromechanical coupling and acoustic impedance is observed. Further results reveal that the use of piezoelectric ceramic matrix does not improve the performance of the composite.     

Design and optimization of MEMS based piezoelectric actuator for drug delivery systems

In this paper, piezoelectric principle based an actuator is design for a micropump, which is suitable for drug delivery systems. The natural frequency and stress analysis have been performed to determine the reliability of the device in terms of minimum safety factor. We have observed the uniform deflections of the actuators by varying the thicknesses of the piezoelectric layer of the actuator. The design of the actuators is considered in circular and rectangular geometry. The materials are selected appropriately such that the component is biocompatible and can be used in biomedical applications. Among the various considerations made on dimensions and geometry, it is observed that the circular piezoelectric actuator undergoes a high displacement of 2950 μm at an infinitesimal thickness of 0.1 μm. At minimum safety factor of one, the maximum stress and voltage the actuator can hold is 596 GPa and 8500 V respectively.

     

一种新的纸基微流开关及其活跃方法

提出了一种新的、基于声表面波的纸基微流开关。通过软光刻技术制作内含两个微孔的聚二甲基硅氧烷(PDMS)微架,其上固定经折叠、长度可变的纸通道。PDMS微架贴附于压电基片之上,并在待连接的两微通道之下方,折叠纸通道最低端离压电基片间距为2 mm。压电基片上采用微电子工艺光刻一对叉指换能器和反射栅。当足够强度的电信号加到叉指换能器对时,激发两相向声表面波,使得压电基片上微流体输运到折叠纸通道,改变其长度,连接其上待连通的两纸基微通道,完成开关功能。对可编程微流器件提供了一种新的编程和开关控制方法。     

基于声表面波技术的微流体混合及仿真

报道了在微流系统中使用基于叉指聚焦换能器的声表面波的一种有效方法.利用lift-off和软光刻技术在铌酸锂( LiNbO3)压电单晶片基底上制作器件.使用有限元分析软件COMSOL Multiphysics分别模拟聚焦叉指电极和平行叉指电极两种声表面波的形成和分布.通过与相同条件下的平行叉指电极比较,说明聚焦叉指电极可...