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首页> 外文会议>Smart Structures and Integrated Systems Mar 3-6, 2003 San Diego, California, USA >Health monitoring of adhesively bonded composite patch repair of aircraft structures using wavelet transforms of lamb wave signals
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Health monitoring of adhesively bonded composite patch repair of aircraft structures using wavelet transforms of lamb wave signals

机译：使用兰姆波信号的小波变换对飞机结构的粘合复合材料贴片修复进行健康监测

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摘要

In recent years there was a need for developing efficient NDE techniques for large area inspection. Conventional ultrasonic inspection techniques such as C-scan and B-scan are very time consuming because the transducer needs to be scanned over each point of structure under the test. Ultrasonically, Lamb wave is considered to be a candidate for large area inspection based on its capability of propagating long distances and its media-thickness dependent propagation properties. Unfortunately, Lamb wave inspection is complicated by the existence of at least two modes at any given frequency. The received signal generally contains more than one mode, and the proportions of the different modes present is modified by the mode conversion at defects. The modes are also highly dispersive in nature. As a result the peak detection and hence the flaw detection with these ultrasonic signals becomes highly complicated and the interpretation of the signals becomes very difficult and also leads to signal-to-noise problems. Consequently, a new kind of signal analysis is required to interpret the results of inspection and to determine if there is a defect or not. In order to extract the information on defects from the Lamb wave signal received by an ultrasonic transducer in such noisy environments, we use a method of analysis based on wavelet transforms. The detection of ultrasonic pulses using wavelet transforms is described and the robustness of this method is verified with testing on samples of adhesively bonded composite patch repair of cracked aluminum panels with simulated flaws.
机译：近年来，需要开发用于大面积检查的有效的NDE技术。常规的超声波检查技术（例如C扫描和B扫描）非常耗时，因为需要在被测结构的每个点上扫描换能器。超声波地讲，兰姆波具有长距离传播的能力和与介质厚度有关的传播特性，因此被认为是大面积检查的候选者。不幸的是，兰姆波检查由于在任何给定频率下至少存在两种​​模式而变得复杂。接收到的信号通常包含一个以上的模式，并且存在缺陷时，通过模式转换可以修改所存在的不同模式的比例。这些模式本质上也是高度分散的。结果，利用这些超声信号的峰值检测以及因此的缺陷检测变得非常复杂，并且信号的解释变得非常困难，并且还导致信噪比问题。因此，需要一种新型的信号分析来解释检查结果并确定是否存在缺陷。为了在这种嘈杂的环境中从超声波换能器接收的兰姆波信号中提取有关缺陷的信息，我们使用了基于小波变换的分析方法。描述了使用小波变换检测超声波脉冲，并通过对带有模拟缺陷的破裂铝板的粘合复合材料修补修复样品进行测试，验证了该方法的鲁棒性。

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