压电陶瓷圆片振子耦合振动的等效电路

在考虑压电效应的情况下,本文对压电陶瓷圆片形振子的耦合振动进行了研究,分析了振子的轴向振动与径向振动之间的相互关系,推出了振子耦合振动的等效电路.在此基础上,得出了振子耦合振动的共振频率方程,并分析了振子的振动模式与共振频率之间的关系.理论分析表明,压电陶瓷振子耦合振动的等效电路在其频率特性分析中是非常方便的,理想振子的一维振动模式是实际振子的一些近似振动模式.可由本文理论直接导出.实验表明,由本文理论得出的振子的共振频率与实测值符合很好.     

一种新型扭转振动压电陶瓷超声换能器

研究了一种新型扭转压电陶瓷超声换能器.基于机电类比原理,对切向极化的压电陶瓷薄圆环振子的扭转振动特性进行了研究,建立了其机电类比等效电路模型,从等效电路得出了环形振子的扭转振动频率方程的解析式及共振频率的计算公式.在此基础上,分析了换能器的共振与其几何尺寸间的关系;并利用有限元方法对压电陶瓷薄圆环扭转振动模态进行了分析.结果表明,在换能器压电陶瓷圆环内外半径比增大时,共振频率随之增大.     

糖类抗原CA125水平测定在结核性腹膜炎诊治中的意义

研究了一种新型扭转压电陶瓷超声换能器.基于机电类比原理,对切向极化的压电陶瓷薄圆环振子的扭转振动特性进行了研究,建立了其机电类比等效电路模型,从等效电路得出了环形振子的扭转振动频率方程的解析式及共振频率的计算公式.在此基础上,分析了换能器的共振与其几何尺寸间的关系;并利用有限元方法对压电陶瓷薄圆环扭转振动模态进行了分析.结果表明,在换能器压电陶瓷圆环内外半径比增大时,共振频率随之增大.     

0压电陶瓷圆片振子耦合振动的等效电路

在考虑压电效应的情况下，本文对压电陶瓷圆片形振子的耦拿辱劝进行了研究，分析了振子的轴向振动与径向振动之间的相互关系，推出了振子耦合振动的等效电路。在此基础上，得出了振子耦合振子的共振频率方程，并分析了振子的振动模式与共振频率之间的关系。理论分析表明，压电陶瓷振子耦合振动的等效电路在其频率特性分析中是非常方便的，理想振子的一维振动模式是实际振子的一些近似振动模式，可由本文理论直接导出。实验表明，由本     

厚度伸缩压电陶瓷振子

对厚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、反谐振频率以及等效电路参数与振子尺寸、振子材料的介电、压电、弹性常数间的关系式.最后讨论了振子的一些特性和制作.     

自由振动压电振子的一种复参数等效电路

将复数概念引入到等效电路元件参数中,并以自由振动压电振子的一种常用振动模——纵向长度伸缩振动模为例,给出了一种复参数等效电路,并推导了等效电路参数与压电材料参数之间相互关系。等效电路元件参数的虚部表示压电振子机械、介电、及压电损耗。给出了由复参数等效电路模型作出的阻抗圆图与由振动理论给出的阻抗圆图以及由传统模型所作出的阻抗圆图。结果表明,新的复参数模型优于传统模型,是一种精确的等效电路。     

复合型超声波电机的振动分析

介绍了一种复合型超声波电机的振动设计理论，这是超声波电机设计理论中的一个重要部分。分析其压电振子的特性，建立压电振子的振动力学模型和相应的等效电路，确定超声波电机振动模态的关键几何参数和物理参数，并给出了样机的研制结果。     

压电陶瓷圆筒振子耦合振动的本征频率分析

研究了压电陶瓷圆筒振子的耦合振动,分析了振子的轴向、径向伸缩振动及扭转振动之间的耦合关系.从理论上推导出了振子耦合振动的共振频率方程.由于分析中对振子的几何尺寸未加任何限制.因此所得结论适用于任何尺寸的陶瓷圆筒振子,其中包括厚壁圆筒及圆环.理论分析表明.本研究计算简单,物理意义明显,与一维理论的结果相比,文中得出的振子耦合振动的共振频率与实测值符合较好.     

纵扭复合型超声波电机压电振子的设计

通过简单推导得出纵、扭振动压电晶片两端的振动方程并在此基础上画出了对应的等效电路图。在压电振子设计过程中,由于纵振子是由整片压电晶片加工而成,设计较为容易,因而压电振子的设计主要是对扭转振子进行设计。扭转振子的设计是以电机力能指标为出发点,通过分析电机的转矩特性得到一系列公式,利用这些公式即可得到扭转振子各部分尺寸。由于电机采用对称结构,在得到扭转振子各部分尺寸后,纵振子的尺寸也就确定了。最后还对     

压电振子结构参数对微雾化器耦合特性的影响

针对微雾化器存在的多能域能量耦合问题,建立了压电微雾化器的固-液-声耦合模型,对其耦合特性进行了数值计算,并着重分析了压电振子结构参数对耦合性的影响,得到了压电振子结构参数对于系统的结构振动、声压力波特性的影响规律。结果表明,由于液体层与固体的耦合作用,压电振子振动的同时,喷孔膜也产生振动,而且两者之间存在相位关系;压电振子的结构参数直接影响结构的耦合性、谐振频率大小以及背膜与喷孔膜的相位差,并且存在最佳的直径比和厚度比。因此,微雾化器设计时只考虑压电振子的振幅是不全面的,必须同时考虑喷孔膜的振动以及与背膜的相位关系,新的设计原则可为微雾化器的优化设计提供指导依据。     

Frequency properties of electrical fields of cylindrical sonar antenna with a flat baffle in the diametral plane

By means of method of coupled fields we obtain analytical relations describing electrical fields of cylindrical piezoceramic antennas with flat baffles in diametral plane. Numerical experiment results of frequency characteristics of antennas’ electrical fields dependently on parameters of antenna elements and embodiment are presented.     

Fabrication and Electromechanical Characterization of a Piezoelectric Structural Fiber for Multifunctional Composites

The use of piezoceramic materials for structural sensing and actuation is a fairly well developed practice that has found use in a wide variety of applications. However, just as advanced composites offer numerous benefits over traditional engineering materials for structural design, actuators that utilize the active properties of piezoelectric fibers can improve upon many of the limitations encountered when using monolithic piezoceramic devices. Several new piezoelectric fiber composites have been developed; however, almost all studies have implemented these devices such that they are surface‐bonded patches used for sensing or actuation. This paper will introduce a novel active piezoelectric structural fiber that can be laid up in a composite material to perform sensing and actuation, in addition to providing load bearing functionality. The sensing and actuation aspects of this multifunctional material will allow composites to be designed with numerous embedded functions, including structural health monitoring, power generation, vibration sensing and control, damping, and shape control through anisotropic actuation. This effort has developed a set of manufacturing techniques to fabricate the multifunctional fiber using a SiC fiber core and a BaTiO₃ piezoelectric shell. The electromechanical coupling of the fiber is characterized using an atomic force microscope for various aspect ratios and is compared to predictions made using finite element modeling in ABAQUS. The results show good agreement between the finite element analysis model and indicate that the fibers could have coupling values as high as 68% of the active constituent used.     

Active vibration control of a flexible one-link manipulator using a multivariable predictive controller

This article presents a new application of model-based predictive controller (MPC) for vibration suppression of a flexible one-link manipulator using piezoceramic actuators. Simulation and experimental studies were conducted to investigate the applicability of the MPC strategy to control vibration of the flexible structure having multiple inputs and multiple outputs (MIMO). The performance of the proposed technique was assessed in terms of level of vibration reduction. The results demonstrated that the proposed predictive control strategy is well suited for multivariable control of vibration suppression on flexible structures.     

3-2型压电复合材料参数对厚度振动模的影响

3-2型压电复合材料在水声换能器应用中主要工作于厚度振动模态。应用切割填充法制备了四种3-2型压电复合材料，并通过改变复合材料中压电陶瓷的体积分数，实验测得了四种3-2型压电复合材料厚度谐振频率随体积分数增加而升高的速率，并分析了不同压电陶瓷与环氧树脂对样品厚度谐振频率变化率的影响。同时分析了复合材料反对称体振动模与厚度振动模的耦合，并提出了避免这种耦合的方法。     

3-2型压电复合材料参数对厚度振动模的影响

3-2型压电复合材料在水声换能器应用中主要工作于厚度振动模态。应用切割填充法制备了四种3-2型压电复合材料,并通过改变复合材料中压电陶瓷的体积分数,实验测得了四种3-2型压电复合材料厚度谐振频率随体积分数增加而升高的速率,并分析了不同压电陶瓷与环氧树脂对样品厚度谐振频率变化率的影响。同时分析了复合材料反对称体振动模与厚度振动模的耦合,并提出了避免这种耦合的方法。     

集中质量对不对称波形成的影响研究

采用Rayleigh-Ritz法初步计算了集中质量对四边简支边界条件下的矩形板振型的影响，由计算结果绘制了矩形板的前两阶振型，并采用有限元法与计算结果进行了对比。分析表明，附加质量能导致波形的不对称且此不对称的振型波形主要是由两相邻阶的模态耦合而成，为压电驱动中不对称波的形成与使用的进一步研究奠定了基础。     

Vibration surveillance supported by Hardware-In-the-Loop Simulation in milling flexible workpieces

The paper concerns modern approaches towards minimising the vibration level during the high speed milling process of flat flexible details. Dynamic analysis of the milling process is performed and dynamics of non-stationary controlled system in hybrid coordinates is described. On the basis of the process dynamics, as well as on the energy performance index, suitable control law is derived in order to reduce vibration level. This control law is applied for active force generation by the piezoceramic plate actuator. The implementation issues, which concern a proposed method of vibration surveillance, are described. At first, in order to predict and obtain good efficiency of vibration surveillance within a wide range of spindle speeds, Hardware-In-the-Loop Simulation (HILS), as a mean of mechatronic design, is applied. Subsequently, the predicted results are verified during the real cutting experiment. The latter ones evidenced good performance in the scope of vibration reduction.     

Embedded explicit model predictive vibration control

This article presents an embedded active vibration suppression system featuring real-time explicit model predictive control (EMPC) that is implemented on a microcontroller unit (MCU). The EMPC controller minimizes the tip deflection of an aluminum cantilever beam driven by piezoceramic actuators, gaining its feedback from direct position measurements. The output and input performance of the EMPC method is compared to an analogously tuned positive position feedback (PPF) controller. An extensive analysis is provided on the cycle timing and memory needs of the explicit predictive vibration control scheme. The results demonstrate that the EMPC controller may achieve the same vibration suppression results compared to PPF with less input effort, while inherently respecting process constraints. Furthermore, we show that EMPC task execution timing is comparable in the random access memory (RAM) and read only memory (ROM) alternatives, suggesting that numerous current microcontrollers are suitable for EMPC-based active vibration control, in case the prediction model is kept simple.     

Construction of Flexible Piezoceramic Array with Ultrahigh Piezoelectricity via a Hierarchical Design Strategy

The µW-level power density of flexible piezoelectric energy harvesters (FPEHs) restricts their potential in applications related to high-power multifunctional wearable devices. To overcome this challenge, a hierarchical design strategy is proposed by forming porous piezoceramics with an optimum microstructure into an ordered macroscopic array structure to enable the construction of high performance FPEHs. The porous piezoceramic elements allows optimization of the sensing and harvesting Figure of merit, and the array structure causes a high level of effective strain under a mechanical load. The introduction of a network of polymer channels between the piezoceramic array also provides increased device flexibility, thereby allowing the device to attach and conform to the curved contours of the human body. The unique hierarchical piezoceramic array architecture exhibits superior flexibility, a high open circuit voltage (618 V), high short circuit current (188 µA), and ultrahigh power density (19.1 mW cm⁻²). This energy density value surpasses previously reported high-performance FPEHs. The ultrahigh power flexible harvesting can charge a 0.1 F supercapacitor at 2.5 Hz to power high-power electronic devices. Finally, the FPEH is employed in two novel applications related to fracture healing monitoring and self-powered wireless position tracking in extreme environments.     

2-2型多基元压电复合陶瓷圆管研究

该文分析并制作了2-2型压电复合陶瓷圆管,陶瓷圆管由180条等分陶瓷基元组成,基元间通过复合材料进行连接。陶瓷圆管采用轴向精密切割工艺,该圆管具有几何尺寸大,基元多,轴向与径向振动相互干扰小,切割工艺精密等特点。研究表明,2-2型压电复合陶瓷圆管与纯压电陶瓷圆管相比,具有在工作频带内模态单一,寄生响应得到了有效抑制等优点,可广泛应用于多波束测深发射阵列的研制。