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题名	环形相控阵换能器辐射和反射声场研究
作者	赖溥祥
学位类别	博士
答辩日期	2005
授予单位	中国科学院声学研究所
授予地点	中国科学院声学研究所
关键词	相控阵 环形换能器 反射声场 声学井下电视
中文摘要	超声相控阵技术能动态地进行聚焦发射和聚焦接收，不受被检物体的形状限制，具有较高的灵敏度、分辨率和信噪比等优点，是目前无损检测领域的研究热点。本文针对超声相控阵技术在声学井下电视的研究和发展现状，开展了环形相控阵换能器辐射声场及其在液一固平面界面上反射声场的理论和实验研究。在环形相控阵列换能器辐射声场方面，我们从圆形活塞声源出发推导和分析了环形相控阵列辐射声场的计算公式，研究了其聚焦声场的轴向、侧向以及全空间声场分布，就阵元数目等参数对声场的影响展开了详细的探讨，证明了环形相控阵列确实具有优越的轴向聚焦能力。关于声场在液固界面上的反射问题，换能器表面上的每一点均可看成点源向外辐射球面波，而将所有点源的球面波求和即得到环形换能器的辐射声场，因此本文从研究球面波及其反射声场出发，首次推导了平面环形相控阵换能器辐射声场在液一固界面上的反射声场的积分表达式，并且借助最陡下降法求得了反射声场的简明解析式，分析了聚焦声束沿其主轴垂直入射时的反射声场，以及不同参数，包括反射介质不同、换能器与反射面距离不同（包括随距离改变焦距和固定焦距，即反射面不在焦平面上）、声束主轴入射角不同对反射声场特性的影响。我们设计和制作了一个由8道同心等面积平面圆环组成的换能器，在其基础上开展了一系列有关辐射声场及其反射声场的实验测量，这些实验主要包括换能器聚焦声场的轴向分布和焦平面测向分布测量，动态扫描聚焦实验，不同反射介质（铝和有机玻璃）、换能器与反射面距离在焦距前后士20mm变化以及换能器倾斜角从。气150变化时一的反射声场测量。实验结果与理论计算结果比较符合，同时也证明换能器在一定轴向范围内可以实现动态聚焦，并且通过反射回波峰值反映反射界面的声学性质、通过反射回波峰值出现的时间来判断反射界面的距离是可行的。我们还开展了裂缝检测及十字形镂空铝板的反射回波幅度成像及反射回波峰值时间成像的初步研究，发现在300kHz的信号频率下能检测出宽度为4mm以上的裂缝和至少5mm的深度变化，取得了较好的结果。
英文摘要	Ultrasonic Phased Array testing can accomplish dynamic focusing and the inspection of workpieces with complex geometry. Also it can improve greatly the detection sensitivity, resolution and SNR, which lead to its high recognition in NDT research domain. Based on the analysis of relational research status in the world at present, the focusing acoustic fields generated by an annular phased array transducer and its reflection filed on the liquid-solid plane surface are studied theoretically and experimentally in this thesis. Based on the acoustic fields in liquids generated by a round PZT piezoelectric ceramic transducer, we study the acoustic fields of an annular phased array transducer, in which the elements are concentric and placed in a plane. The computational expression is obtained, and the acoustic fields in longitudinal and transversal directions are discussed in the case of different transducer parameters, such as number of the elements, width of the elements, spacing between the elements, the working frequency and the position of the preset focus, etc, showing its prominent focusing characteristics. As concerning to the reflection fields on the liquid-solid surface, many researches have been paid attention to plane and spherical waves, while about the waves excited by an annular array, few can be referred to at the moment. As we know, every tiny unit of the transducer can be regarded as a point source, radiating spherical waves. Were they Put together, the fields of the transducer are obtained. So, the exploration of the reflection acoustic fields of the transducer is deployed with the sum of the reflection fields of spherical waves. The ray approach method (saddle-point method) is adopted to investigate the far distribution of the reflection fields. A concise analytic expression is achieved, with which the reflection fields of the annular phased array on the water-aluminum surface is computed and analyzed numerically. In experiment, an annular transducer with 8 equal-area elements is designed and fabricated, and a series of experiments about the radiant acoustic fields and its reflection on the liquid-solid surface are carried out. The experimental characteristics of the transducer are in good agreement with the numerical ones, demonstrating the feasibility of dynamic focusing of our system, and with the value of maximum and its emergence time of the reflecting waves, we can acquire information indirectly of the acoustic parameters of the reflecting surface and the distances between the transducer and the reflecting surface. In addition, the aluminum plates with cracks and cross grooves are scanned for primary acoustic imaging. Good results are obtained. It is found that with a wok frequency of 300kHz, the phased array system can detect cracks 4mm wide and less than 5mm deep. With amelioration, the system can be applied to industrial inspection and imaging, for example, Acoustic Borehole Televiewer (BHTV).
语种	中文
公开日期	2011-05-07
页码	101
内容类型	学位论文
源URL	[http://159.226.59.140/handle/311008/988]
专题	声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文
推荐引用方式 GB/T 7714	赖溥祥. 环形相控阵换能器辐射和反射声场研究[D]. 中国科学院声学研究所. 中国科学院声学研究所. 2005.

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