Abstract The carbon fiber reinforced polymer (CFRP) has been widely used in the aerospace field. During its utilization under the severe environment, CFRP is prone to defects, including impacts, debonds, delaminations, and cracks. Optical pulsed thermography (OPT) nondestructive testing has been used for qualitative and quantitative analysis of such defects. This paper proposes the nonlinear transfer model of peak contrast time analysis to determine defect depth by using OPT technology. The mechanism of the nonlinear relationship between peak contrast time and defect depth is demonstrated and validated by experiments. To effectively predict the defect depth, gaussianization transform is modeled as a nonlinear conversion in defects depth determination. The results of the experiments have indicated that the proposed method has significantly enhanced the accuracy in depth determination.

中文翻译：

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基于非线性变换的脉冲热像检测缺陷深度反演方法

摘要 碳纤维增强聚合物（CFRP）已广泛应用于航空航天领域。CFRP在恶劣环境下使用过程中，容易产生冲击、脱粘、分层、裂纹等缺陷。光学脉冲热成像 (OPT) 无损检测已被用于此类缺陷的定性和定量分析。本文提出了利用OPT技术确定缺陷深度的峰值对比度时间分析的非线性传递模型。通过实验证明并验证了峰值对比度时间与缺陷深度之间非线性关系的机制。为了有效地预测缺陷深度，高斯化变换被建模为缺陷深度确定中的非线性转换。