Malyarenko E V, Hinders M K
Department of Applied Science, College of William & Mary, Williamsburg, Virginia 23187-8795, USA.
J Acoust Soc Am. 2000 Oct;108(4):1631-9. doi: 10.1121/1.1289663.
As the worldwide aviation fleet continues to age, methods for accurately predicting the presence of structural flaws-such as hidden corrosion and disbonds-that compromise airworthiness become increasingly necessary. Ultrasonic guided waves, Lamb waves, allow large sections of aircraft structures to be rapidly inspected. However, extracting quantitative information from Lamb wave data has always involved highly trained personnel with a detailed knowledge of mechanical waveguide physics. The work summarized here focuses on a variety of different tomographic reconstruction techniques to graphically represent the Lamb wave data in quantitative maps that can be easily interpreted by technicians. Because the velocity of Lamb waves depends on thickness, for example, the traveltimes of the fundamental Lamb modes can be converted into a thickness map of the inspection region. This article describes two potentially practical implementations of Lamb wave tomographic imaging techniques that can be optimized for in-the-field testing of large-area aircraft structures. Laboratory measurements discussed here demonstrate that Lamb wave tomography using either a ring of transducers with fan beam reconstructions, or a square array of transducers with algebraic reconstruction tomography, is appropriate for detecting flaws in multilayer aircraft materials. The speed and fidelity of the reconstruction algorithms as well as practical considerations for person-portable array-based systems are discussed in this article.
随着全球航空机队不断老化，准确预测影响适航性的结构缺陷（如隐藏的腐蚀和脱胶）的方法变得越来越必要。超声导波，即兰姆波，可对飞机结构的大片区域进行快速检测。然而，从兰姆波数据中提取定量信息一直需要训练有素且精通机械波导物理的人员。本文总结的工作聚焦于多种不同的层析重建技术，以便在定量图中以图形方式呈现兰姆波数据，技术人员能够轻松解读这些图。例如，由于兰姆波的速度取决于厚度，因此基本兰姆模式的传播时间可以转换为检测区域的厚度图。本文描述了兰姆波层析成像技术的两种潜在实用实现方式，可针对大面积飞机结构的现场测试进行优化。此处讨论的实验室测量结果表明，使用具有扇形束重建的换能器环或具有代数重建层析成像的换能器方形阵列进行兰姆波层析成像，适用于检测多层飞机材料中的缺陷。本文还讨论了重建算法的速度和保真度以及基于便携式阵列系统的实际考量。
