OPTIMIZATION OF LAMB WAVE INSPECTION TECHNIQUES
OPTIMIZATION OF LAMB WAVE INSPECTION TECHNIQUES
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DOI：
10.1016/0963-8695(92)90003-y
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发表时间：
1992-01-01
影响因子：
4.2
通讯作者：
CAWLEY, P
中科院分区：
文献类型：
--
作者：
ALLEYNE, DN;CAWLEY, P
兰姆波可以长距离传播，这意味着它们对于大型结构的快速、长距离检测是有吸引力的，并且它们也可以用于局部检测，特别是在薄结构中。本文讨论了根据不同的检测要求选择合适的模式和频率范围，并评述了可能的激励、响应测量和信号处理方法。它通常是理想的传输一个单一的，非色散模式，和激励方法来实现这一点进行了讨论。从简单的时域到相对复杂的二维傅立叶分析的各种信号处理技术都是可用的。时域处理通常可以令人满意地应用于低频厚度区域，其中只有两种模式可以传播，但在a1模式的截止频率以上往往是不可靠的。作为一个例子的兰姆波检测制度的设计，一组对对接焊接钢板与不同深度的模拟焊接缺陷的测试进行了说明。它示出的是，通过以下操作的a1截止频率与明智的选择的测试技术，可以可靠地检测到缺陷的存在，从接收到的波形的形状的变化。
Lamb waves can propagate over long distances which means that they are attractive for the quick, long range inspection of large structures, and they can also be useful for localized inspection, particularly in thin structures. This paper discusses the selection of the appropriate mode and frequency range for different inspection requirements and reviews the possible methods of excitation, response measurement and signal processing. It is usually desirable to transmit a single, non-dispersive mode, and excitation methods to achieve this are discussed. A variety of signal processing techniques from simple time domain to relatively complex two-dimensional Fourier analysis are available. Time domain processing can often be applied satisfactorily in low frequency-thickness regions where only two modes can propagate, but tends to be unreliable above the cut-off frequency of the a1 mode. As an example of the design of a Lamb wave testing regime, a set of tests on a butt-welded steel plate with simulated weld defects of different depths is described. It is shown that by operating below the a1 cut-off frequency with judicious selection of testing technique, the presence of defects can be detected reliably from changes in the shape of the received waveform.