铌酸钾钠基无铅压电陶瓷纵振换能器*

高性能环境友好型无铅压电陶瓷及其应用是当前压电材料研究的热点之一,为了探究其在水声换能器领域的应用潜力,该文对铌酸钾钠基无铅压电陶瓷和锆钛酸铅压电陶瓷纵振式换能器进行了对比研究。依据仿真结果优化结构尺寸,制作了两种换能器样机并测试了其在空气中和水中的电声性能。测试结果表明,铌酸钾钠基无铅压电陶瓷换能器的谐振频率为35kHz,最大发送电压响应为 151dB,声源级可达 190dB,在 26kHz~67kHz 的频率范围内发送电压响应的起伏不超过±4.5dB,谐振频率处-3dB 的指向性开角约为 76°。该无铅压电陶瓷换能器具有和锆钛酸铅压电陶瓷换能器相当的发射性能,有望推动无铅压电材料在水声换能器领域的应用进程。     

自由端盖Ⅲ型宽带弯张换能器的设计

提出了一种利用多模耦合实现低频、宽带、大功率特性的新结构Ⅲ型弯张换能器。通过在压电陶瓷堆内部嵌入与凹型弯张壳体相连的弹性辅助弯曲梁结构,并用弯曲圆盘作为顶部自由端盖,增加有效工作模态。利用有限元方法对换能器进行了设计优化,分析结果显示换能器在低频段存在4个主要工作模态。根据优化结果,加工制作了换能器样机,水池实验的测试结果表明:在1.5～5.5 kHz范围内,换能器样机的发送电压响应均大于135 dB;1.5～4 kHz内的最大发送电压响应大于142 dB,响应起伏小于6 dB。研究结果表明自由端盖Ⅲ型弯张换能器不仅能够在小尺寸设计下实现大功率工作,还能获得低频宽带发射性能。      

混合激励纵振换能器的研究

纵振式换能器是水声领域中不可或缺的一类中频段换能器,本文以超磁致伸缩材料Terfenol-D和压电陶瓷材料PZT作为驱动元件设计混合激励纵振式换能器。利用ANSYS有限元软件建立了有限元模型,对换能器的电声参数进行了优化,并制作一宽带混合激励纵振式换能器,实验测得的换能器与仿真的结果较为吻合,实测换能器的最大发送电压响应为145dB,其工作频带为4kHz-16kHz,频带内发送电压响应起伏为±4.5dB。     

磁致伸缩-压电联合激励凹简型发射换能器

设计制作了一种新型磁致伸缩-压电联合激励凹简型发射换能器,采用稀土超磁致伸缩材料Terfenol-D与PZT压电陶瓷作为联合激励元件,模拟计算与实测结果均表明,与采用单一振子激励的凹筒型发射换能器相比,此种新型换能器在保持尺寸小、频率低等优点的同时,显著拓宽了工作频带并提高了辐射声功率。换能器外型尺寸为φ88 mm×316 mm,水中谐振频率1．30 kHz,-3 dB带通Q值1．43,谐振频率下发射电压响应级135．1 dB。     

磁致伸缩-压电联合激励凹筒型发射换能器

设计制作了一种新型磁致伸缩-压电联合激励凹筒型发射换能器,采用稀土超磁致伸缩材料Terfenol-D与PZT压电陶瓷作为联合激励元件,模拟计算与实测结果均表明,与采用单一振子激励的凹筒型发射换能器相比,此种新型换能器在保持尺寸小、频率低等优点的同时,显著拓宽了工作频带并提高了辐射声功率.换能器外型尺寸为φ88 mm×316 mm,水中谐振频率1.30 kHz,-3 dB带通Q值1.43,谐振频率下发射电压响应级135.1 dB.     

多谐振宽带Janus-Ring换能器

提出了一种多谐振宽带Janus-Ring换能器,两个一定距离的压电圆环换能器(Ring换能器)嵌套在双面纵振Janus换能器的两端,Ring换能器的径向振动、Janus换能器的纵振动与它们中间形成的Helmholtz液腔振动相耦合,可大大拓展换能器的工作带宽。使用有限元方法设计并研制了Janus-Ring换能器样机,经测试在1.8~8.0 kHz范围内,样机最大发射电压响应144 dB,起伏小于6 dB。相比传统的Janus-Helmholtz换能器,Janus-Ring换能器有效拓展了工作频带,增大了发射电压响应,减小了频带内的发射电压响应起伏。      

压电管堆式宽带换能器*

研究了一种具有管状叠堆结构的圆管换能器,其敏感元件是由纵向极化压电陶瓷单元组成的薄壁管状压电叠堆,探讨利用管状叠堆纵向和径向振动耦合实现宽带发射。利用压电柱壳振动理论推导了管堆的频率方程,分析了换能器的纵向和径向模态的振动耦合特性。在理论分析的基础上利用有限元方法对换能器的带宽和发射电压响应进行优化并研制换能器样机。测试结果表明,纵向极化的管状压电叠堆结构具有良好的发射电压响应和宽带特性,与理论及仿真结果相符。     

四边型弯张换能器特性研究及宽带设计

四边型弯张换能器通常工作带宽较窄,为了提高带宽性能,对四边型弯张换能器振动及辐射特性进行了研究,重点分析壳体结构参数对换能器发送电压响应的影响。根据分析结果提出了拓宽换能器工作带宽的方法,利用有限元软件进行了仿真计算并制作了四边型弯张换能器样机。测量得到在2.4~5 kHz的频率范围内,换能器的最大发送电压响应值达到140 dB,带内起伏4 dB,有限元仿真结果与实验结果吻合较好。研究结果表明设计的四边型弯张换能器不仅能够低频工作,并且可以在小尺寸下实现大功率发射,同时还具备宽带发射特性。      

双椭圆壳串联宽带弯张换能器

提出一种利用多模态耦合的低频、宽带、大功率的新型弯张换能器,其结构上将两椭圆的Ⅳ型弯张壳体沿长轴方向串联为一体,两组长压电陶瓷堆贯穿其中驱动。利用有限元软件设计并制作一款此新型换能器的样机,其工作频带通过耦合壳体前三阶弯曲模态及压电陶瓷堆纵振模态与壳体膜模态的复合模态展宽。经测试在1.4~6.0 kHz范围内,样机的发射电压响应大于128.5dB,声源级大于190dB。结果表明,此弯张换能器与只利用一阶弯曲模态的Ⅳ型弯张换能器相比不仅有更宽的工作带宽,还满足低频和大功率的声辐射要求。      

铁镓单晶Janus-Helmholtz换能器

针对深水、低频、宽带换能器的技术需求,结合Janus-Helmholtz换能器的结构特点和铁镓单晶材料低场应变大及机械强度高的特性,提出了铁镓单晶Janus-Helmholtz换能器设计方案。采用永磁偏磁场和环形闭合磁路,建立了一系列铁镓单晶磁致伸缩换能器理论分析模型,包括对磁致伸缩材料参数进行线性化处理,设计了换能器最佳工作点,结合静态磁场和动态磁场分布情况分段细化换能器驱动等效参数,以及利用全阻抗模型通过电感损耗等效计算换能器静态阻抗,然后通过二维有限元分析等效模型,优化分析了换能器的结构参数与电声性能。最后制作了换能器样机,并进行了测试与分析。对比仿真和测试结果表明:全阻抗模型得到的阻抗曲线与样机测试结果相一致,有限元等效模型计算的发送电流响应与样机测试结果良好吻合。换能器样机水中谐振基频为1000 Hz,谐振频率下发送电流响应176.4 dB;在875～2300 Hz频率范围内,发送电流响应起伏不大于6 dB;增加驱动电流有效值到16.2 A,最大声源级可以达到196.2 dB。     

A hybrid magnetostrictive-piezoelectric barrel-stave projector

A hybrid magnetostrictive-piezoelectric barrel-stave projector is designed and developed. The new type transducer is driven by the union of rare-earth giant magnetostrictive material Terfenol-D and PZT piezoelectric ceramic. Combining the advantages of low frequency performance within a compact size, it proves that the hybrid projector has a much broader band and higher sound power than that with single magnetostrictive or piezoelectric driver by the simulated and measured results. The prototype of the hybrid projector has a size of 88 mm in outside diameter and 316 mm in length, with an underwater resonant frequency of 1.30 kHz, Q factor of 1.43 for -3 dB bandwidth, and transmitting voltage response level of 135.1 dB at the resonant frequency.     

Multi-resonant broadband Janus-Ring transducer

A Janus-Ring(JR) transducer with two piezoelectric rings placed around a Janus driver is presented.The rings have radial vibration,whereas the Janus has longitudinal vibration,and a resonance of Helmholtz cavity is observed between them.By joining the three resonances,the working frequency bandwidth of the transducer is prominently widened.After simulation using finite element method,a prototype is finally fabricated and tested.Results show that in the working frequency of 1.8 to 8.0 kHz,the maximum transmitting voltage response(TVR) is 144 dB,and the fluctuations are less than 6 dB.Compared with traditional Janus-Helmholtz transducers,the JR transducer has the characteristics of wider bandwidth,greater TVR,and less fluctuations of TVR in working frequency band.     

折回型纵向振子低频拼合圆柱换能器

提出一种具有小尺寸、低频、水平无指向性的新结构换能器——折回型纵向振子拼合圆柱换能器,换能器由4组共享尾质量块的折回型压电纵向振子正交布置驱动环形辐射面拼合构成。采用有限元方法对换能器进行优化设计,并制作了换能器样品。实验结果表明:换能器直径为Φ180 mm,谐振频率为1.5 kHz,最大发射电压响应为131 dB,最大声源级不低于188 dB,水平全向。该换能器具有低频、小尺寸、水平无指向性的特点,具有良好的应用前景。      

基于球形压电陶瓷的耐压水听器

利用球形压电陶瓷自身所具有的耐压能力,采用径向极化空气背衬压电球壳换能器作为声学接收敏感元件,设计并制作了一种球形耐压水听器。首先对其低频开路接收灵敏度和谐振频率等声学特性进行了分析和有限元仿真,然后对其强度和稳定性等耐压性能进行了分析和有限元仿真,最后对其声学性能和耐压能力进行了测试。测试表明,该球形耐压水听器的直径为36 mm,工作频段为50 Hz～10 kHz,低频接收灵敏度为-198.4 dB (0 dB=1 V/μPa),等效自噪声谱级为46.5 dB@1 kHz,其耐压深度可达3000 m。该耐压水听器为大深度水听器设计提供了参考,在深水声学领域具有重要的应用价值。     

Cymbal piezoelectric composite underwater acoustic transducer

The working principle of Cymbal piezoelectric composite underwater acoustic transducer was studied in this paper. PZT-5A piezoelectric ceramic disk was used as piezoelectric phase and brass foil was used as end cap electrode of the Cymbal transducer. The silicon rubber was used as the insulated proof layer of the underwater acoustic transducer. The properties of this transducer used as hydrophone, such as operation frequency, free-field voltage receiving sensitivity and directivity, were investigated. Several kinds of prototype of this transducer were fabricated and the properties of this transducer used as hydrophone were tested. The results show that the properties of this transducer used as hydrophone depend on the dimensions of Cymbal transducer because the piezoelectric properties of this transducer are dependent on the dimensions of Cymbal transducer's end caps. The appropriate dimensions for getting higher free-field voltage receiving sensitivity with -184.7 dB were obtained.     

Application of piezoelectric transient response in transducer acoustic power measurement

To explore a more convenient method for measuring the focused ultrasound power,a piezoelectric ceramic plate was used to receive ultrasonic signal directly.Due to an acoustic force acts on the surface of piezoelectric ceramic plate,the piezoelectric response was obtained by means of electromechanical analogy,which was composed of voltage response caused by forced vibration and high frequency attenuation response caused by natural vibration.The conversion relationship between output signal of piezoelectric ceramic plate and acoustic power of transducer was analyzed.The envelope of output piezoelectric signal was extracted in twice,and a voltage amplitude curve with sinusoidal distribution that could describe the changes of acoustic power was obtained.Under different drive voltage of transducer,the maximum peak voltage of envelope curve was found respectively.Their squared values were made a linear fitting with acoustic power measured by acoustic power meter,and then the proportional coefficient of theoretical relational expression was calibrated.The experimental results are in good agreement with the theory.The relative error between calibrated theoretical acoustic power and that measured by acoustic power meter was less than 8.7%.The paper can provide a guideline for measuring acoustic power of transducer by using piezoelectric signal.     

基于2-2型压电复合材料的新型宽频带径向振动超声换能器

本文提出了一种基于2-2型压电复合材料的新型宽频带径向振动超声换能器,它主要由内金属圆环和外压电陶瓷复合材料圆环组成.首先利用Newnham串并联理论和均匀场理论推导了2-2型压电复合材料的等效参数;其次利用解析法得到了金属圆环和径向极化压电复合陶瓷圆环径向振动的机电等效电路;最后得到了换能器的六端机电等效电路,从而得到了换能器的频率方程.接着分析了换能器共振频率和反共振频率以及有效机电耦合系数与几何尺寸、两相体积占比的关系,采用仿真软件对新型换能器的径向振动进行了数值模拟.结果表明,利用解析法得到的共振频率和反共振频率与数值模拟结果吻合较好.此外,对换能器在水下的辐射声场进行了仿真研究,结果表明新型复合材料径向换能器相比传统纯陶瓷径向换能器,发射电压响应幅值更大,工作带宽提高接近一倍,声匹配更佳.