扭转振动压电超声换能器的研究

用声强技术检测区分板壳结构的空气传声与结构传声时，结构的辐射效率之差决定了检测结果的可信度，文中分析了实际结构的在声场激励下的实测辐射效率与无限大结构的空气传声辐射效率之差，及对区检测结果的影响。实验结果证实了理论分析。     

扭转振动压电超声换能器的研究

本文对夹心式复合结构压电超声扭转振动换能器进行了系统的理论研究，该换能器由两段金属真圆棒及切向极化的压电陶瓷圆片堆复合而成，文中首先研究了切向极化压电陶瓷细长管的扭转振动性，推出了其机电等效电路，并提出了压电陶瓷细长管截面扭转系数的概念。，     

A3夹心式压电超声扭转换能器的研制

本文对夹心式压电超声扭转振动换能器进行了理论及实验研究，得出了对称型扭转振动夹心换能器的共振频率设计方程，给出了频率方程式中一些主要的物理量的具体表达式。在此基础上，实际设计并制作了一个夹心扭转振动换能器，并对其所有的电声参数进行了测试     

A3 夹心式压电超声扭转换能器的研制

本文对夹心式压电超声扭转振动换能器进行了理论及实验研究，得出了对称型扭转振动夹心换能器的共振频率设计方程，给出了频率方程式中一些主要的物理量的具体表达式，在此基础上，实际设计提供制作了一个夹心扭转振动换能器，并对其所有的电声参数进行了测试。     

A high sensitivity hydrostatic piezoelectric transducer based ontransverse piezoelectric mode honeycomb ceramic composites

A new piezoelectric composite transducer based on the ceramic honeycomb structure is introduced. The transducer is operated in the transverse piezoelectric (TP) d₃₁ mode. The ceramic honeycomb configuration enables one to fabricate a TP honeycomb transducer by either embedding a honeycomb ceramic skeleton into a soft polymer matrix to form a composite or by blocking the openings of the honeycomb cells with thin layers of epoxy to form an end-capped honeycomb structure. With the unique honeycomb configuration and TP operation mode, the piezoelectric d₃₃ response of the ceramic is nearly eliminated and the piezoelectric responses from the three orthogonal directions add together when the transducer is subjected to a hydrostatic pressure. As a result, the transducer exhibits exceptionally high hydrostatic piezoelectric response     

压电换能器的热仿真分析

压电换能器在工作过程中的发热,不仅会引起换能器的性能下降,而且还可能导致换能器失效.基于传热学的基本理论,应用ANSYS有限元分析软件,建立了压电换能器的热分析模型.采用有限差分的数值求解方法,对换能器的整体温度场进行了求解,分析了前后质量块采用不同材料的Langevin换能器的温度场分布规律,为大功率压电换能器的散热和性能优化方法的研究提供了基础.     

A smooth impact rotation motor using a multi-layered torsional piezoelectric actuator

A smooth impact rotation motor was fabricated and successfully operated using a torsional piezo actuator. Yoshida et al. reported a linear type smooth impact motor in 1997. This linear motor demonstrated a high output force and a long stroke. A superior feature of the smooth impact drive is a high positioning resolution compared with an impact drive. The positioning resolution of SIDM (smooth impact drive mechanism) is equal to the piezo displacement. The reported positioning resolution of the linear type was 5 nm. Our rotation motor utilized a torsional actuator containing multi-layered piezoelectric material. The torsional actuator was cylindrical in shape with an outer diameter of 15 mm, an inner diameter of 10 mm, and a length of 11 mm. Torsional vibration performance was measured with a laser Doppler vibrometer. The obtained torsional displacement agreed with the calculated values and was sufficient to drive a rotor. The rotor was operated with a saw-shaped input voltage (180 V; 8 kHz). The revolution direction was reversible. The maximum revolution speed was 27 rpm, and the maximum output torque was 56 gfcm. In general, smooth-impact drives do not show high efficiency; however, the level of efficiency of our results (max., 0.045%) could be increased by improving the contact surface material. In addition, we are studying quantitative consideration, for example, about the optimum pre-load or frictional force.     

Unidimensional modeling of multi-layered piezoelectric transducer structures

Multi-layered transducer structures offer the potential of improved performance in terms of increased transmit sensitivity, greater bandwidth, and enhanced reception characteristics. Unfortunately, the successful design of such devices is often difficult, owing to the complex interaction between the active piezoelectric layers and passive intermediate interface layers. Furthermore, in many practical applications, the loading effects imposed by the electrical drive circuitry often limit the performance improvements that may be physically realized. This paper describes the development of a comprehensive, unidimensional modeling approach. This model may be employed to facilitate the analysis and subsequent optimization of laminated transducer assemblies. The devices currently under consideration include both piezoceramic and piezopolymer configurations, as well as alternative piezocomposite designs. The effects of varying bondline thickness and the introduction of passive interface layers are examined, as is the influence of the electrical load circuitry on overall system response. The ability to accurately predict the response of stacked piezoelectric structures is demonstrated through extensive comparison of experimental and theoretical responses. This paper concludes by highlighting the important role that modeling plays in the design, fabrication, and optimization of complex multi-layered transducer assemblies.     

用于水下金属探测成像的压电式微机械超声波换能器

为满足目前对水下金属、蛙人等检测的应用需要,设计一种用于水下金属探测成像的压电式微机械超声换能器。在该结构中,在顶部电极和下电级之间插入AlN层,用于发射和接收超声。当测试距离达到10 m以上就可以满足实际应用需求,而该换能器经过实验得出最远的测试距离为12.8 m,且在12.8 m处测试值与理论值误差仅为0.67 cm,完全可以达到实际检测需要。在一个标准大气压下,利用微系统激光分析仪MSA400对该传感器进行膜位移测量,其测量值为0.28μm,与理论结果误差为1%。并且详细介绍该传感器的工艺实现过程。利用该传感器实现二维水下超声成像,证明水下存在金属矩形物体。该实验有利于水下超声成像系统的建立。     

压电水声换能器的声学特性分析

压电水声换能器是一种既能作为驱动器又能作为传感器工作的水下探测装置。准确预测其在嘈杂水下环境中的声学特性对设计出坚固耐用的换能器是十分重要的。有限元方法对分析换能器在不同环境中的各种性能十分有效和实用。建立了一种Tonpilz型换能器的二维轴对称有限元模型,设计了基于有限元方法的程序,对其进行了动力学分析,包括模态分析和谐响应分析等,获得了一些声学特性。该程序分析的结果与ANSYS软件分析的结果显示出较好的吻合性。     

夹心式功率超声压电陶瓷换能器的工程设计

文中为换能器的优化设计和性能改善提供一些有用的设计指南和解决措施,并对功率超声夹心式压电陶瓷换能器工程设计中的一些重要问题(即换能器各部分的功能及选择,压电陶瓷元件的位置优化,接触界面对换能器性能的影响与预应力的选择及影响等)进行了简要的分析。结论表明,文中所述对于优化设计、改善并提高性能具有参考和使用价值。     

A block diagram model of the thickness mode piezoelectric transducer containing dual oppositely polarized piezoelectric zones

A unidimensional, linear systems, block diagram model of a two-layer thickness mode piezoelectric transducer is presented. The layers are subject to opposing piezoelectric polarization and the device is assumed to be loaded by semi-infinite isotropic media at the two principal faces. Block diagram representations of the transducer acting as both a generator and a receiver of ultrasound are developed in conjunction with the equivalent model of the electrical admittance. When expressed in this manner, the underlying cause and effect relationships are identified, with the important contribution of the piezoelectric boundary highlighted. Comparisons with the conventional single-layer transducer are made throughout and the major physical differences in terms of transduction performance are discussed. The new model is compared with finite element analysis and good agreement is also demonstrated with experimental data. A key aspect of the methodology is the provision of a more intuitive understanding of such device behavior. Accordingly, emphasis has been placed on the physical relationships and this is considered a major contribution of the work.     

一种基于压电晶片阵列的板结构损伤识别方法

提出一种通过单个压电晶片对板结构进行激励,使用十字形压电晶片阵列接收响应信号,然后基于相控阵原理对信号进行处理,从而对板结构损伤进行识别的方法。首先用谱元法分析了在单点激励下铝板结构有损伤和无损伤时Lamb波的传播情况,得到压电晶片阵列中各阵元所在位置的响应信号。根据压电晶片阵列布置形式及各阵元之间的相互位置,对各阵元接收到的时域信号进行处理,从而对结构的损伤进行识别。通过对板结构中含有一个和两个损伤的情况进行了研究,验证了该方法的有效性。     

A flex-compressive-mode piezoelectric transducer for mechanical vibration/strain energy harvesting

A piezoelectric transducer for harvesting energy from ambient mechanical vibrations/strains under pressure condition was developed. The proposed transducer was made of two ring-type piezoelectric stacks, one pair of bow-shaped elastic plates, and one shaft that pre-compresses them. This transducer works in flex-compressive (F-C) mode, which is different from a conventional flex-tensional (F-T) one, to transfer a transversely applied force F into an amplified longitudinal force N pressing against the two piezo-stacks via the two bowshaped elastic plates, generating a large electric voltage output via piezoelectric effect. Our experimental results show that without an electric load, an F-C mode piezo-transducer could generate a maximum electric voltage output of up to 110 Vpp, and with an electric load of 40 κΩ, it a maximum power output of 14.6 mW under an acceleration excitation of 1 g peak-peak at the resonance frequency of 87 Hz.     

Discussion of one-D piezoelectric transducer models with loss

Two, 1-dimensional piezoelectric transducer models are presented that use complex numbers to represent mechanical and dielectric loss. Exact numerical agreement was achieved by avoiding a number of small errors in the literature. A correction to Kino's simplified Mason parallel equivalent circuit is also given. Efficiency is discussed.     

A review on the development of piezoelectric composites forunderwater acoustic transducer applications

For future sonar transducer applications that emphasize the detection of acoustical signals in a hydrostatic mode, new piezoelectric composite materials have been developed. Ceramic-polymer composites having `1-3' and `0-3' connectivity patterns are shown to exhibit much higher sensitivities than conventional PZT ceramics. Glass-ceramic composites are free of aging, and have potential applications in standard transducers     

Compensation of torsional vibrations in rods by piezoelectric actuation

In this paper, the piezoelectric compensation of torsional vibrations in rods caused by external excitations is studied. As an illustrative example, a laminated rod containing piezoelectric shear actuators is assumed to be fixed at the one end, and the other end is subjected to a torsional couple; additionally, a distributed torsional couple per unit length is acting. In such a system, cross-sectional warping is known to be present. The consideration of piezoelectric eigenstrains requires an extension of Saint Venant’s theory of torsion, which is achieved by introducing an additional warping function. Using D’Alembert’s principle, the boundary value problems for Saint Venant’s warping function, the additional warping function and the torsional angle are obtained. From the latter boundary value problems, the distribution of piezoelectric actuation is derived in order to completely compensate the external excitations, i.e. an analytical solution of the corresponding shape control problem is obtained. Finally, the results are verified by means of three-dimensional finite element computations.