To improve the acoustic radiation performance of the spherical transducer, a prestressed layer is formed in the transducer through fiber winding. The influence of the prestressed layer on the transducer is studied from the effects of the radial prestress (Tr) and acoustic impedance, respectively. First, a theoretical estimation of Tr is established with a thin shell approximation of the prestressed layer. Then, the acoustic impedance is measured to evaluate the efficiency of sound energy transmission within the prestressed layer. Further, the ideal effects of Tr on the sound radiation performances of the transducer are analyzed through finite element analysis (FEA). Finally, four spherical transducers are fabricated and tested to investigate their dependence of actual properties on the prestressed layer. The results show that with the growth of Tr, the acoustic impedance of the prestressed layer grows, mitigating the enormous impedance mismatch between the piezoelectric ceramic and water, while increasing attenuation of the acoustic energy, resulting in a peak value of the maximum transmitting voltage response (TVRmax) at 1.18 MPa. The maximum drive voltage increases with Tr, leading to a steady growth of the maximum transmitting sound level (SLmax), with a noticeable ascend of 3.9 dB at a 3.44 MPa Tr. This is a strong credibility that the prestressed layer could improve the sound radiation performance of the spherical transducer.To improve the acoustic radiation performance of the spherical transducer, a prestressed layer is formed in the transducer through fiber winding. The influence of the prestressed layer on the transducer is studied from the effects of the radial prestress (Tr) and acoustic impedance, respectively. First, a theoretical estimation of Tr is established with a thin shell approximation of the prestressed layer. Then, the acoustic impedance is measured to evaluate the efficiency of sound energy transmission within the prestressed layer. Further, the ideal effects of Tr on the sound radiation performances of the transducer are analyzed through finite element analysis (FEA). Finally, four spherical transducers are fabricated and tested to investigate their dependence of actual properties on the prestressed layer. The results show that with the growth of Tr, the acoustic impedance of the prestressed layer grows, mitigating the enormous impedance mismatch between the piezoelectric ceramic and water, while increasing attenuation of the acoustic energy, resulting in a peak value of the maximum transmitting voltage response (TVRmax) at 1.18 MPa. The maximum drive voltage increases with Tr, leading to a steady growth of the maximum transmitting sound level (SLmax), with a noticeable ascend of 3.9 dB at a 3.44 MPa Tr. This is a strong credibility that the prestressed layer could improve the sound radiation performance of the spherical transducer.

有机-无机压电材料是一种分子铁电体, 具有柔性、结构灵活、易成膜、全液相合成及环保节能等优点, 可满足新一代薄膜器件及可穿戴设备的需求。该文以三甲基卤代甲基铵(TMXM, X=F, Cl, Br)为有机部分, MnCl2为无机部分, 通过溶液蒸发法制备了具有钙钛矿分子结构的有机-无机压电材料三甲基氯三氯化锰(TMCM-MnCl3), 并对其分子结构组成、压电、热学、声学及铁电性进行表征。结果表明, TMCM-MnCl3的压电常数为106 pC/N, 居里温度为130 ℃, 声阻抗值约为16.5 MRayl, 低于压电陶瓷PZT-4(大于33 MRayl), 具有广阔的应用前景。

匹配层材料及结构对于提高阵列式换能器的带宽、灵敏度及轴向分辨率有重要作用。为了探究不同匹配层材料对阵列式换能器性能的影响，该文通过有限元法模拟了包括高分子材料、0-3复合材料及镁合金等多种匹配层材料的阵列式换能器，综合比较了各自的频域特性及时域特性。仿真结果表明，使用AZ31B镁合金作为第一匹配层、Epo-Tek 301环氧树脂作为第二匹配层的阵列式换能器模型具有最佳的综合性能，从而为高性能阵列式压电超声换能器的开发、研究提供了新的匹配层设计参考方案。

一定厚度的低声阻抗支撑层可以在薄膜体声波谐振器(FBAR)与衬底之间形成声学隔离层, 防止声波泄漏到衬底当中。掺碳二氧化硅(CDO)是一种低声阻抗材料, 对FBAR具有较好的温度补偿效果, 可以作为FBAR与衬底之间的声学隔离层, 从而构成一种新型的CDO-FBAR。为了分析CDO-FBAR与通孔型FBAR相比性能是否退化, 以及CDO声学隔离层所需厚度, 采用多物理场耦合仿真软件分析了CDO-FBAR和通孔型FBAR的谐振频率、Q值、有效机电耦合系数和S参数, 并提取了CDO-FBAR纵向振动位移。分析结果表明: CDO-FBAR的谐振频率整体向下漂移; CDO声学隔离层导致S参数的寄生干扰; 由于声学损耗增加, Q值略有降低, 其中并联谐振点处的Q值降幅更大; 有效机电耦合系数略有降低; 声波传播到声学隔离层中9 μm处就完全衰减, 即只需要9 μm厚的CDO声学隔离层就能在FBAR与衬底之间形成有效的声学隔离。由此, 仿真验证了这种新颖的CDO-FBAR结构的可行性。

激光冲击过程中，剩余吸收层对冲击效果影响显著，但其影响规律少有人关注。文中选择厚度、材质不同的材料作吸收层，实施激光冲击，控制激光参数，使得靶材表面留有剩余吸收层。通过表征靶材表面冲击区域凹坑尺寸、力学性能，以及直接检测冲击时靶材背面的冲击波信号，研究剩余吸收层对冲击效果的影响规律。结果表明：剩余吸收层会显著衰减冲击波，进而削弱靶材的冲击效果；对确定的约束层和靶材，存在具有“最佳声阻抗值”的理想吸收层，使得作用于靶材的冲击波强度最大；激光冲击时，为获得好的冲击效果，必须根据约束层、靶材等，选择合适吸收层，优化吸收层涂覆厚度。文中结果为激光冲击时吸收层材质和厚度的选择提供了依据。