1-3型压电复合材料壳式聚焦换能器的研究

为解决压电陶瓷聚焦换能器阻抗高、带宽窄,电声转换效率低等问题,采用新型的1-3型压电复合材料作为聚焦超声换能器材料,设计并制作了一种新型的1-3压电复合材料壳式聚焦换能器。通过对新型换能器的频率特性,电声转换效率研究后和当前应用的PZT壳式聚焦换能器进行对比,证明了1-3型压电复合材料壳式聚焦换能器的阻抗较低,相对带宽达61%,是PZT压电陶瓷壳式聚焦换能器的3.39倍,以及较高的电声转换效率η为54%,是PZT压电陶瓷壳式聚焦换能器的1.68倍。将换能器实际声场检测结果与Matlab声场仿真结果进行对比研究,得出换能器具有较好的声场特性及聚焦效果。为高性能的聚焦换能器的实现提供了理论及实验基础。     

PZT/环氧树脂1-3-2型压电复合材料的制备及性能

采用压电陶瓷基板与1-3型压电复合材料串联连接,沿表面两相互垂直的方向切割PZT陶瓷,在切槽间浇注环氧树脂,制备出新型的1-3-2型压电复合材料.实验测试了材料的压电和介电性能,结果表明其d33常数达到400 pC/N,振动位移113.5pm,声速3500m/s,声阻抗17.6Mraly,厚度机电耦合系数0.62,带宽3.6kHz,相对介电常数817,介质损耗0.02.     

一种分析非均匀厚度1-3型压电复合材料换能器性能的方法

非均匀厚度1-3型压电复合材料可用于制作宽带压电换能器,已广泛应用于水浸无损探伤、声波测井以及超声成像等领域。为分析该换能器的振动及其性能,提出了一种并联振子等效电路模型,将非均匀厚度1-3型压电复合材料换能器看成并联的谐振器阵列,采用三维厚度伸缩振动模型对单个谐振器单元进行理论分析,得出了非均匀厚度1-3型压电复合材料换能器的阻抗计算公式;为验证该模型的正确性,设计并制作了一个平凹的1-3型压电复合材料换能器;实验结果显示,并联振子等效电路模型能准确的分析非均匀厚度1-3型压电复合材料片的性能。结果表明,非均匀厚度换能器带宽的主要是由压电片的厚度差异决定,研究结果可为非均匀厚度宽带换能器的设计提供参考。     

PZT压电复合材料圆环性能仿真和制备

高频宽带全向换能器是水声换能器研究的发展方向,PZT压电复合材料圆环既能够水平全向发射和接收水声信号,同时又使换能器的带宽得到扩展。利用ANASYS有限元仿真软件对2-2型压电复合材料圆环结构进行模态仿真,得到带宽和结构尺寸的关系曲线。在仿真模拟的基础上,形成设计方案,将压电陶瓷圆环沿轴向方向均匀切割,把环氧树脂浇注于切槽,经打磨和被覆电极,制成2-2型压电复合材料圆环。对压电复合材料圆环的压电和介电性能进行测试,结果为谐振频率388k Hz,带宽11.2k Hz,声阻抗18.05Mraly,相对介电常数859,声速3200m/s,d33常数480 p C/N,振动位移89.5pm。该压电复合材料圆环适合做水平全向宽带换能器。     

1-3型压电复合材料和普通PZT换能器性能对比分析

通过切割-填充法制备了1-3型压电复合材料，并选取相同尺寸的1-3型压电复合材料和普通PZT圆片制成活塞型换能器，经测量得到了两种换能器在空气中和水中的导纳曲线，水中发送电压响应、接收灵敏度和指向性曲线。通过对比分析，得出1-3型压电复合材料换能器比普通PZT压电换能器的收发性能有明显改善。     

一种超声手术刀推挽激励换能器的研究

设计了一种超声手术刀用的新型推挽激励换能器。它是在夹心式单晶堆压电超声换能器的经典构造基础上,把原先激励一组压电陶瓷晶片堆的方式,改为同时施加反相激励的前后两组晶堆。利用有限元方法,对该推挽激励换能器进行模态分析和频率响应分析。在相同大小的电压激励下,相对单晶堆换能器,推挽激励换能器可以获得更高的工作带宽和机电耦合系数,提高了换能器的电声转换效率。按照仿真结果加工推挽激励换能器,实现良好的动力学和电学特性,满足设计要求。     

1-1-3型压电复合材料的振动模态研究

对1-1-3型压电复合材料进行了振动形态的分析。1-1-3型压电复合材料选用PZT-5H、硅橡胶和环氧树脂制备而成。从制备的两组样品的实验证明该复合元件相比传统的1-3型压电复合材料具有较高的机电耦合系数和较低的声阻抗。通过PSV-400型激光测振仪测量其振动形态,发现其中压电陶瓷柱的振动为主动振动,模态为电场平行于长度方向的纵向伸缩模态。该结构的复合元件充分发挥了压电柱本身的压电性能,进而提高了整个元件的压电性能,使得该复合元件更适合应用于水声换能器。     

准1-3复合型压电换能器的研制

水声高频换能器在水声领域具有广泛运用,然而常规厚度振动高频换能器在高频段存在强烈的高次径向耦合振动,制作出的换能器出现了阻抗曲线杂乱,相位一致性差,电声效率低的问题。设计制作了一种单一振动模态的换能器,通过将常规厚度振动换能器陶瓷片切割成密排矩形颗粒,再用环氧树脂将切缝填充满。制作两片直径为55mm的准1-3复合材料,由该材料制作的换能器谐振频率为293kHz,谐振点阻抗50,3dB阻抗带宽23.5 kHz,3dB开角为5.75°,50W电功率输出声源级达到217.5dB。通过该工艺可以消除高频厚度振动换能器的高次径向耦合振动,提高高频厚度振动换能器的电声转换效率和一致性,并能实现批量制作,为高频换能器在水声领域的广泛运用提供了新的手段。     

聚偏氟乙烯压电薄膜的实验研究

一、聚偏氟乙烯薄膜性能特点 聚偏氟乙烯(以下称为PVDF)薄膜为一种新型压电材料,在水声、超声、电声等领域中可与现有的PZT压电陶瓷取长补短,是压电材料领域新添的一员。 自从五十年代PZT压电陶瓷问世以来,三十多年中它始终在换能器材料中占主导地位,尽管PZT作为压电材料有着无可比拟的优点,但也存在着由陶瓷固有性能所带来的缺点和在换能器设计上的不便之处,如陶瓷的高密度和易碎性使大于10cm的水听器太厚、太重,而薄的器件     

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     

Modeling and fabrication of a piezoelectric vibration‐induced micro power generator

Abstract

In this paper, theoretical and experimental study on a piezoelectric vibration‐induced micro power generator that can convert mechanical vibration energy into electrical energy is presented. The mechanical‐electrical energy conversion mechanism is a voltage between two capacitors, which belong to the mechanical and the piezoelectric equivalent circuits, respectively. To verify the theoretical analysis, two clusters of transducer structures are fabricated. Piezoelectric lead zirconate titanate (PZT) material is chosen to make the energy conversion transducer. The desired shape of the piezoelectric generator with its resonance frequency in accordance with the ambient vibration source is designed by finite element analysis (FEA).

Experimental results show that the maximum output voltages are generated at the first mode resonance frequencies of the structure. The overall conversion efficiency is measured to be 33%. The experimental results coincide with the theoretical analysis.     

Influence of the connectivity pattern,the nature of the piezoelectric material,and rod thickness on the properties of 50 vol % PZT/50 vol % NiCo0.02Cu0.02Mn0.1Fe1.8O4 − δ magnetoelectric composites

We have studied the influence of the connectivity pattern, the nature of the piezoelectric material, and rod thickness on the properties of magnetoelectric composites with the composition 50 vol % PZT/50 vol % NiCo_0.02Cu_0.02Mn_0.1Fe_1.8O_{4 ? δ} (where PZT stands for various commercially available lead zirconate titanate based piezoelectric materials). The results indicate that the magnetoelectric conversion efficiency of the rod composites with any connectivity pattern (1-1, 1-3, or 3-1) is 10–20% higher than that of laminate composites. The largest magnetoelectric conversion coefficient ΔE/ΔH is offered by the 1-1 connectivity composites. The ΔE/ΔH of the composites correlates with both their piezoelectric sensitivity g ₃₃ and the piezoelectric sensitivity of the corresponding piezoelectric materials. ΔE/ΔH is shown to be inversely proportional to the thickness of the piezoelectric and ferrite rods. The highest ΔE/ΔH at a frequency of 1 kHz, 450 mV/(cm Oe), has been reached in the PZT-36 based composites with 1-1 connectivity and 0.3-mm-thick rods.     

Fabrication and performance of endoscopic ultrasound radial arrays based on PMN-PT single crystal/epoxy 1-3 composite

In this paper, 0.7Pb(Mg(1/?)Nb(2/?)O?-0.3PbTiO? (PMN-PT) single crystal/epoxy 1/3 composite was used as the active material of the endoscopic ultrasonic radial array transducer, because this composite exhibited ultrahigh electromechanical coupling coefficient (k(t) = 0.81%), very low mechanical quality factor (Q(m) = 11) and relatively low acoustic impedance (Z(t) = 12 MRayls). A 6.91 MHz PMN-PT/epoxy 1/3 composite radial array transducer with 64 elements was tested in a pulseecho response measurement. The -6-dB bandwidth of the composite array transducer was 102%, which was ~30% larger than that of traditional lead zirconate titanate array transducer. The two-way insertion loss was found to be -32.3 dB. The obtained results show that this broadband array transducer is promising for acquiring high-resolution endoscopic ultrasonic images in many clinical applications.     

A cylindrical micro ultrasonic motor using PZT thin film deposited by single process hydrothermal method (phi2.4 mm, L=10 mm stator transducer)

A micro ultrasonic motor using PZT (lead zirconate titanate) thin film has been improved by a single process hydrothermal method. The hydrothermal method is a unique method for depositing PZT thin film in a solution. An earlier reported hydrothermal method consisted of two linked processes. Our new method, however, has only a single process. Hence, less distribution of chemical components of the PZT film contributes to a higher efficiency of the stator transducer. The piezoelectric factor d(31) was -30 pC/N for this new method, which is six times larger than that of the previous method. The output torque of the micro ultrasonic motor fabricated by the single process hydrothermal method was measured. The output torque was 7.0 muNm, and the maximum revolution speed was 880 rpm at 15 Vp-p driving voltage.     

Fabrication and evaluation of a single-element Bi(0.5)Na(0.5)TiO(3)-based ultrasonic transducer

This paper discusses the fabrication and characterization of a single-element ultrasonic transducer with a lead-free piezoelectric active element. A piezoelectric ceramic with composition of 0.88Bi(0.5)Na(0.5)TiO(3)-0.08Bi(0.5)K(0.5)TiO(3)- 0.04Bi(0.5)Li(0.5)TiO(3) was chosen as the active element of the transducer. This composition exhibited a thickness coupling coefficient (kt) of 0.45, a dielectric constant of 440 (at 1 kHz), and a longitudinal piezoelectric coefficient (d(33)) of 84 pC?N(-1). To make the transducer, the ceramic was sandwiched between an epoxy-tungsten backing layer and a silver epoxy matching layer. An epoxy lens was also incorporated into the transducer?s design to focus the ultrasound beam. The focused transducer with a center frequency of about 23 MHz demonstrated a -6-dB bandwidth of 55% and an insertion loss of -32 dB; the -20-dB pulsed length was measured to be 150 ns. A phantom made of copper wires (30 μm in diameter) was utilized to investigate the imaging capability of the transducer. The results indicated that the fabricated transducer, with a lateral resolution of 260 μm and a relatively high depolarization temperature, could be considered as a candidate for replacement of lead-based ultrasonic transducers.     

PLZT陶瓷纤维/环氧树脂1-3复合材料的制备和性能研究

以乙酸铅、乙酸镧、乙酸氧锆和钛酸丁酯为原料,用溶胶-凝胶法制备了掺镧锆钛酸铅(PLZT)凝胶纤维.该纤维经热解、烧结后成为直径约25μm的陶瓷纤维.陶瓷纤维的表面和断面形貌的电子扫描图象表明,该陶瓷纤维均匀致密.用阿基米德法测得陶瓷纤维的密度为:7.78×10³kg/m³.对于直径为4.4mm、厚度为43μm、陶瓷含量为70％的PLZT陶瓷纤维/环氧树脂1-3复合材料压电片,测得其压电常数d₃₃、机电转换常数k_t分别为:410pC/N和0.631.     

基于拓扑优化的压电分流阻尼抑振实验研究

将结构拓扑优化引入压电分流振动抑制中,以压电元件的分布面积为设计变量,压电元件产生的电荷最大化为优化目标,对压电元件的拓扑进行了优化以获得最佳抑振效果。针对悬臂梁结构,得到了对不同的结构模态进行抑制时的压电元件最优拓扑构型。建立了带有压电分流阻尼系统的悬臂梁振动控制实验模型,将压电元件拓扑优化后的压电分流阻尼系统应用于悬臂梁多阶弯曲模态的振动响应抑制实验,并对比分析了带最优拓扑和非优拓扑压电元件的悬臂梁压电分流阻尼抑振效果。结果表明,对压电元件进行拓扑优化可以明显提高压电分流阻尼系统的抑振效果。     

Preparation and Properties of 1-3 Piezoelectric Composite Transducers

This study demonstrated the preparation of 1-3 piezoelectric composite transducers by using 1-3 piezoelectric composites as the active phases, air as the backing layer and polyurethane as the matching layer. The composite electrode was produced by electroless nickel coating and the effect of the matching layer on transducer performance was investigated in detail. The results showed that the matching layer could improve the receiving sensitivity of the transducer significantly. The receiving response value of the transducer at first increased and then decreased with the increase of the matching layer thickness. This receiving response had the largest head-wave amplitude value when the thickness of the matching layer was about 2.2 mm, which was in good agreement with the theoretical value. The resonance frequency of the transducer in water showed a tendency of low frequencies, and the bandwidth of the transducer in water became much wider than that in air. The reasonable matching layer could improve performance of the transducer effectively.