Micromachined ultrasonic transducers for air-coupled nondestructive evaluation
Micromachined ultrasonic transducers for air-coupled nondestructive evaluation
复制标题
用于空气耦合无损评估的微机械超声换能器
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
B. Khuri
中科院分区：
文献类型：
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作者：
S. Hansen;F. Degertekin;B. Khuri
传统的超声波无损评估 (NDE) 方法使用液体将声波耦合到测试样品中。这要么需要将待检查的部件浸入水中，要么使用必须在整个结构上进行扫描的复杂且笨重的喷水系统。如果空气-固体界面处的损耗可以忍受，那么空气耦合超声波系统就可以消除这些要求。微机械电容式超声波换能器 (cMUT) 已被证明在双基地传输模式下使用时具有超过 100 dB 的动态范围。在本文中，我们展示了使用 cMUT 实现 103 dB 动态范围的一发一收传输系统的结果。每个传感器由 10,000 个直径为 100 微米的氮化硅膜并联组成。这种几何形状导致换能器的谐振频率约为 2.3 MHz。这些换能器可用于垂直入射到样品的传输实验，或激发和检测铝板和复合板中的导波。在本文中，我们介绍了铝板和复合板（例如飞机中使用的板）的透射和引导兰姆波实验的超声波缺陷检测结果。
Conventional methods of ultrasonic non-destructive evaluation (NDE) use liquids to couple sound waves into the test samples. This either requires immersion of the parts to be examined or the use of complex and bulky water squirting systems that must be scanned over the structure. Air-coupled ultrasonic systems eliminate these requirements if the losses at air-solid interfaces are tolerable. Micromachined capacitive ultrasonic transducers (cMUTs) have been shown to have more than 100 dB dynamic range when used in the bistatic transmission mode. In this paper, we present results of a pitch-catch transmission system using cMUTs that achieves a 103 dB dynamic range. Each transducer consists of 10,000 silicon nitride membranes of 100 micrometers diameter connected in parallel. This geometry result in transducers with a resonant frequency around 2.3 MHz. These transducers can be used in transmission experiments at normal incident to the sample or to excite and detect guided waves in aluminum and composite plates. In this paper we present ultrasonic defect detection results from both through transmission and guided Lamb wave experiments in aluminum and composite plates, such as those used in aircraft.