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：
10.1177/10453890122145348
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发表时间：
1999-06
影响因子：
2.7
通讯作者：
P. Wilcox;M. Lowe;P. Cawley
中科院分区：
文献类型：
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作者：
P. Wilcox;M. Lowe;P. Cawley
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。在特定应用中选择哪种兰姆波模式取决于许多因素，包括所需的分辨率、待检测的缺陷或损伤类型、衰减和可用的换能选项。本文提出了一个合理的程序，确定合适的兰姆波模式和工作频率为特定的检测任务。它示出，待检查的系统的属性确定可以使用的模式和频率，这然后决定所需的换能器的类型。兰姆波换能器的性能评估程序也证明。作为说明性示例，示出了公知的角度入射换能技术通常不适合于待检查的结构是液体加载的应用。在这种情况下，有必要考虑替代换能选项，如电磁声换能器（EMAT）或剪切压电装置。
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. The choice of which Lamb wave mode to use in a particular application depends on numerous factors, including the resolution required, the type of defects or damage to be detected, the attenuation and the available transduction options. This paper sets out a rational procedure for identifying suitable Lamb wave modes and operating frequencies for a particular inspection task. It is shown that the properties of the system to be inspected determine which mode and frequencies can be used, and that this then dictates the type of transducer required. A procedure for evaluating the performance of Lamb wave transducers is also demonstrated. As an illustrative example, it is shown that the well known angle incidence transduction technique is not generally suitable in applications where the structure to be inspected is liquid loaded. In such cases it is necessary to consider alternative transduction options such as electromagnetic acoustic transducers (EMATs) or shear piezoelectric devices.