Quantifying corrosion damage is vital for the petrochemical industry, and guided wave tomography can provide thickness maps of such regions by transmitting guided waves through these areas and capturing the scattering information using arrays. The dispersive nature of the guided waves enables a reconstruction of wave velocity to be converted into thickness. However, existing approaches have been shown to be limited in in-plane resolution, significantly short of that required to accurately image a defect target of three times the wall thickness (i.e. 3 T) in each in-plane direction. This is largely due to the long wavelengths of the fundamental modes commonly used, being around 4 T for both A0 and S0 at the typical operation points. In this work, the suitability of the first-order shear-horizontal guided wave mode, SH1, has been investigated to improve the resolution limit. The wavelength at the desired operating point is significantly shorter, enabling an improvement in resolution of around 2.4 times. This is first verified by realistic finite-element simulations and then validated by experimental results, confirming the improved resolution limit can now allow defects of maximum extent 3T-by-3T to be reliably detected and sized, i.e. a long-pursued goal of guided wave tomography has been achieved.

中文翻译：

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使用 SH1 导波断层扫描的高分辨率腐蚀厚度图

量化腐蚀损伤对于石化行业至关重要，导波断层扫描可以通过将导波传输穿过这些区域并使用阵列捕获散射信息来提供这些区域的厚度图。导波的色散特性使波速度的重建能够转换为厚度。然而，现有方法已被证明在面内分辨率方面受到限制，明显低于在每个面内方向上准确成像壁厚（即 3 T）三倍的缺陷目标所需的分辨率。这主要是由于常用基模的长波长，A0 和 S0 在典型工作点的波长都在 4T 左右。在这项工作中，一阶横切水平导波模式 SH1 的适用性，已被调查以提高分辨率限制。所需工作点的波长明显更短，分辨率提高了约 2.4 倍。这首先通过真实的有限元模拟进行验证，然后通过实验结果进行验证，确认改进的分辨率限制现在可以允许最大程度的 3T×3T 缺陷被可靠地检测和确定尺寸，即导波长期追求的目标断层扫描已经实现。