Mode and transducer selection for long range Lamb wave inspection
Mode and transducer selection for long range Lamb wave inspection
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DOI：
10.4028/www.scientific.net/kem.167-168.152
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发表时间：
1999-01-01
期刊：
影响因子：
--
通讯作者：
Cawley, P
中科院分区：
文献类型：
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作者：
Wilcox, PD;Dalton, RP;Cawley, P
兰姆波可以沿沿着板壳结构传播数米，因此在“智能结构”应用中具有很大的潜力，其中换能器询问周围结构的显著区域是重要的。然而，存在许多不同类型的兰姆波，并且为了获得可以可靠地解释的简单信号，重要的是在良好控制的方向上激发单模。本文讨论了大型厚板结构（如储油罐）和薄板结构（如飞机蒙皮）的不同模态选择要求。结果表明，最合适的模式是强烈依赖于什么板是在接触。特别是，液体加载板的情况下进行检查。它示出的系统的属性被检查确定哪些模式可以使用，这然后决定所需的换能器的类型。它示出的换能器，主要适用于平面外的力量，如传统的压电器件一般不适合在涉及液体加载或衰减涂层的应用。在这些情况下，有必要考虑替代方案，如电磁声换能器（EMAT）。
Lamb waves can propagate many metres along plate and shell structures, and so have great potential in 'smart structure' applications where it is important for a transducer to interrogate a significant area of the surrounding structure. However, there are many different types of Lamb wave and in order to obtain simple signals that can be reliably interpreted, it is important to excite a single mode in a well controlled direction. This paper discusses the differing mode selection requirements for large, thick plate structures such as oil storage tanks, and thin plate structures such as aircraft skins. It is shown that the most suitable mode is strongly dependent on what the plate is in contact with. In particular, the case of liquid loaded plates is examined. It is shown that the properties of the system to be inspected determine which modes can be used, and that this then dictates the type of transducer required. It is shown that transducers which apply predominantly out-of-plane forces such as conventional piezoelectric devices are not generally suitable in applications involving liquid loading or attenuative coatings. In these cases it is necessary to consider alternatives such as electro-magnetic acoustic transducers (EMATs).