Abstract In this paper, terahertz (THz) imaging and vibro-thermography (VT) are implemented for non-destructive evaluation (NDE) of CFRP subjected to impact damage. THz inspection is well-known for its outstanding detection depth in dielectric materials but unreliable in conductive materials like carbon fiber reinforced plastics (CFRP): an unwanted electro-magnetic wave will be excited under the irradiation of THz waves in conductive molecules and interrupted the reflective waves leading to a blur in the detection results. However, our experimental results showed THz imaging is comparable when it’s used to detect surface defects and shallow ones caused by impact loads. We conducted a set of VT tests as a contrast test, and the VT data are processed by Fourier transform and eigenvector decomposition algorithms, i.e. independent component analysis (ICA). Compared with VT, THz imaging show more details on surface defects and shallow-buried ones due to the absence of thermal diffusion effects. THz imaging could perform non-invasive, non-ionizing and non-contact inspection on the impact damage based on the differences in reflective index. In the end, signal-to-noise (SNR) evaluation is used as an effective means to quantitatively compare the results of these two techniques.

中文翻译：

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用于碳纤维增强塑料冲击响应的太赫兹成像和振动热成像

摘要 在本文中，太赫兹 (THz) 成像和振动热成像 (VT) 被用于对受到冲击损坏的 CFRP 进行无损评估 (NDE)。太赫兹检测以其在介电材料中出色的检测深度而闻名，但在碳纤维增强塑料 (CFRP) 等导电材料中不可靠：在太赫兹波照射导电分子中会激发不需要的电磁波并中断反射波导致检测结果模糊。然而，我们的实验结果表明，太赫兹成像在检测表面缺陷和由冲击载荷引起的浅层缺陷方面具有可比性。我们进行了一组VT测试作为对比测试，VT数据经过傅里叶变换和特征向量分解算法处理，即 独立成分分析 (ICA)。与VT相比，由于没有热扩散效应，太赫兹成像显示了更多表面缺陷和浅埋缺陷的细节。太赫兹成像可以根据反射率的差异对冲击损伤进行非侵入性、非电离和非接触式检测。最后，使用信噪比 (SNR) 评估作为定量比较这两种技术结果的有效手段。