横场长度伸缩压电陶瓷振子

本文对典型的横场长度伸缩压电陶瓷振子的振动状态进行了分析并得到其等效电路。推导了振子的谐振频率、反谐振频率、等效电路参数与振子材料的介电常数、压电常数、弹性常数之间的关系式。最后讨论了振子的某些特性。     

压电圆环厚度振动分析

应用压电本构方程,通过分析圆环径向小体元的振动,将其等效为长度伸缩振动模态,以简化圆环的运动方程,推导其径向厚度振动的谐振频率。采用有限元分析法对圆环进行建模仿真,计算出圆环谐振频率,并用阻抗测量法实测圆环实体振动进行比较,结果表明圆环厚度为4～9 mm时吻合较好。     

悬臂梁压电振子频率调谐和发电能力研究

研究了一种带末端质量块的悬臂梁压电振子的频率调谐能力。理论分析了悬臂梁压电振子的结构尺寸对压电振子谐振频率和发电能力的影响关系,并分别对长度调谐和质量调谐前后的压电振子发电能力进行实验测试和对比分析。结果表明,增加悬臂长度或末端质量可以降低压电振子的谐振频率,减少悬臂长度或末端质量可以提高压电振子的谐振频率,但为达到更好的发电效果,降频调谐时,应该采用质量调谐法提高压电振子的输出功率,而升频调谐时．应该采用长度调谐法提高压电振子的输出功率．     

矩形板压电振子型超声马达

在双矩形板压电振子型超声马达研究的基础上，提出了一种具有四个凸起物的单矩形板压电振子型超声马达，利用矩形板的双向弯曲振动合成了凸起物顶部的椭圆运动，引用耦合振动理论研究了矩形薄板的固有弯曲振动频率，并通过研制与试验，测试了样机的速度与效率性能，验证了其工作的可行性。     

特种压电陶瓷变压器的研制

简要讨论了压电变压器的工作原理和结构及压电材料的选择。报道了铌镁锰锆钛酸四元系压电陶瓷材料的概况，设计并制作了一种带宽窄、升比和转换效率高的ＥＴ型压电陶瓷变压器。通过有关单位试用性试验，能达到了引爆要求。     

PZT-PZN-NaNbO3压电陶瓷的结构和性能

对（1-x）Pb0.95Sr0.05[（Zr0.54Ti0.46）0.9（Zn1／3 Nb2／3）0.10]O3＋xNaNbO3（简称PZT-PZN-XaXbO3）压电陶瓷的结构和性能进行了研究。结果表明，随着NaNbO3掺入量的强加，d33，Kp和介电常数εr同步增加，当添加2.5mol％NbNaO3时，材料的晶体结构由三方相向四方相转变，在准同型相界处，d33和Kp以及介电常数εr达到最大值，继续增加NaNbCO3掺入量，d33，Kp和介电常数εr开始下降；NaNbO3还可以促进陶瓷烧结，降低烧结温度；通过NaNbO3掺杂改性，得到了d33=510PC/N，Kp=0、62，εr=2600，tanδ=0．024的压电陶瓷。     

新型压电输送振子振动模态有限元分析

利用ANSYS有限元分析软件,对用于行波型超声物料输送装置的压电输送振子进行了模态分析,讨论了压电输送振子结构参数对振动模态的影响,为压电输送振子进一步的结构参数修改提供了指导,为行波型超声物料输送装置的设计奠定了基础。     

悬臂梁单晶压电振子发电的理论建模与仿真

为了解决电池为低功耗电子产品供能存在的诸多问题,对悬臂梁单晶压电振子的发电能力进行了研究.根据压电理论和热平衡原理,建立悬臂型单晶压电振子发电能力的数学模型,并对金属基板材料、基板厚度与压电片厚度对压电梁发电能力的影响进行了数值模拟与有限元仿真分析.研究结果表明,建立的数学模型与有限元仿真分析结果一致,压电片与基板材料存在一个最佳厚度比使得压电振子的输出电压达到最优,且最佳厚度比随着基板材料弹性模量的增大而增大,当基板材料分别为铝、磷青铜、多晶硅和钢时,单晶压电振子所对应的最佳厚度比分别为0.4、0.5、0.55和0.65,最后对以磷青铜为基板材料的压电振子进行了实验测试.实验结果表明,当压电片与基板厚度比为0.5时,压电振子输出功率最大,验证了理论分析的正确性.     

应用压电振子测量稳恒电流磁场的可行性分析

提出利用压电振子外接高频正弦电压信号下的振动驱动导线在磁场中运动以产生动生电动势，并以此来获得稳恒电流磁场中空间某处磁感应强度量值的方法。     

压电超声换能器电端匹配下的电流反馈式频率跟踪

介绍了具有电流反馈式频率跟踪功能的超发生器的系统结构;详细阐述了电流反馈式频率跟踪的原理;在分析了匹配电路对压电超声换能器谐振频率影响的基础上,指出匹配条件下对压电换能器进行电流反馈式频率跟踪可能会误跟踪到非谐振频率点;进行条件下的电流反馈式频率自动跟踪方法的研究,进一步完善了电流反馈式频率自动跟踪方法。     

加载可调同轴谐振腔谐振频率的计算

此文针对一种实用的、宽带可调窄通带、同轴加载型滤波器中谐振腔的谐振频率进行了深入详尽的讨论。对于腔中的同轴线终结于圆波导缝隙电容,和同轴线内导体不连续性电容进行了精确的变分分析。该方法对于其它单、双端口元件的分析具有普遍意义。     

Identification of complex compliance for regenerator in thermoacoustic resonator system

In thermoacoustic system, the characteristic of complex compliance of a regenerator has a great influence on energy stored and dissipation of the whole engine. In order to investigate the performance of regenerators with different matrix geometries and materials coupled with different acoustic systems, an experimental measurement and analysis method was presented. By measuring the resonant frequency, the complex compliance and quality factor of five kinds of matrix were experimentally analyzed respectively in the system of loudspeaker-driven thermoacoustic resonator (TAR) with different lengths. The experimental results show that the real part of complex compliance of the regenerator with pin-array has a maximum value among the measured matrixes and its quality factor is the largest (28.222) with the least dissipation factor of 0.035 4. So the pin-array matrix is testified to behave more excellently on the energy conversion than other matrixes. Compared with other factors the complex compliance of a regenerator contributes more to the performance of a thermoacoustic system. Foundation item: Projects(50676068, 50576024) supported by the National Natural Science Foundation of China     

并联谐振电路最大阻抗性能的研究

对于由至少一个电感器和一个电容器组成的二端网络,当二端网络的输入阻抗是纯电阻性时,电路发生了谐振。当二端网络外加一个幅度恒定的正弦电流源,电压响应正比于电路的输入阻抗。文章证实了并联谐振电路中电压响应的最大值不是发生在谐振频率处,而是发生在谐振频率附近。     

石英晶体谐振器探测沉积膜层的特性

本文介绍压电石英晶体谐振器探测沉积膜厚度及速率的工作原理。根据石英晶体和沉积膜层的切变弹性声阻抗理论,并利用在界面处的输入阻抗概念,导出了沉积一种材料膜层时复合系统的谐振频率变化与沉积层材料声阻抗和质量之间的理论关系式,进而导出了沉积多种材料膜层系时的理论关系式。这些关系式是使用石英谐振器精确探测沉积膜层的科学依据。     

In-situ measurement of elastic modulus for ceramic top-coat at high temperature

The ceramic thermal barrier coatings (TBCs) play an increasingly important in advanced gas turbine engines because of their ability to further increase the engine operating temperature and reduce the cooling, thus help achieve future engine low emission, high efficiency and improve the reliability goals. Currently, there are two different processes such as the plasma spraying (PS) and the electron beam-physical vapor deposition (EB-PVD) techniques. The PS coating was selected to test the elastic modulus. Using the nanoindentation and resonant frequency method, the mechanical properties of ceramic top-coat were measured in-situ. According to the theory of the resonant frequency and composite beam, the testing system was set up including the hardware and software. The results show that the accurate characterization of the elastic properties of TBCs is important for stress-strain analysis and failure prediction. The TBCs systems are multi-layer material system. It is difficult to measure the elastic modulus of top-coat by tensile method. The testing data is scatter by nanoindentation method because of the microstructure of the ceramic top-coat. The elastic modulus of the top-coat between 20?1 150 ℃ is obtained. The elastic modulus is from 2 to 70 GPa at room temperature. The elastic modulus changes from 62.5 GPa to 18.6 GPa when the temperature increases from 20 ℃ to 1 150 ℃.     

Fuzzy control on automatic frequency tracking of ultrasonic vibration system with high power and high quality factor Q

In order to realize automatic tracking drift of resonance frequency of ultrasonic vibration system with high power and high quality factor Q,adaptive fuzzy control was studied with a self-fabricated ultrasonic plastic welding machine.At first,relations between amplitude of vibration and frequency as well as main loop current and amplitude of vibration were analyzed.From this analysis,we deduced that frequency tracking process of the vibration system can be concluded as an optimizing problem of one dimensional fluctuant extremum of main loop current in vibration system.Then a method of self-optimizing fuzzy control,used for the realization of automatic frequency tracking in vibration system,is presented on the basis of self-optimizing adaptive control approach and fuzzy control approach.The result of experiments shows that the fuzzy self-optimizing method can solve the problem of tracking frequency drift very well.Response time of tracking in the system is less than 50 ms,which basically meets the requirements of frequency tracking in ultrasonic plastic welding machine.