基于磁场梯度脉冲涡流检测的航空结构亚表面腐蚀缺陷可视化方法

恶劣复杂的服役环境致使航空金属结构极易出现亚表面腐蚀等缺陷，严重影响结构完整性。作为一种结合匀场激励的新型脉冲涡流检测方法，磁场梯度脉冲涡流检测已在结构腐蚀缺陷检测和评估方面体现了其优势性。针对所获取亚表面腐蚀缺陷图像信息不够丰富等不足，结合积分计算对所获图像进行进一步处理，提取图像新特征，研究其与亚表面腐蚀缺陷深度间的映射关系。研究结果表明：该图像新特征与亚表面腐蚀缺陷深度呈单调递增关系；综合由此建立的关联曲线和已获取的亚表面腐蚀缺陷图像，可对金属结构亚表面腐蚀缺陷的深度、形貌、开口尺寸等进行定量评估。

Visualization of Subsurface Corrosion in Aviation Structures Based on Gradient-Field Pulsed Eddy Current Testing

Hostile and complex environment causes the subsurface corrosion for in service aviation structures, posing a severe threat to the structural integrity. As for the integration of pulsed eddy current testing with uniform excitation yields Gradient field Pulsed Eddy Current testing(GPEC), the gradient field pulsed eddy current testing has reflected its advantages in detection and evaluation of corrosion in conductive structures. This paper focuses on experimental investigation of GPEC further. Aimed at the problems that the imaging information of subsurface corrosion obtained in aviation structures is not abundant, the paper further proposes the relevant imaging processing along with a new image feature proposed. The proposed imaging processing method is further discussed regarding superiority in subsurface corrosion visualization. The results show that the image feature extracted from the post processing images has the linear correlation with the corrosion depth, which, in conjunction with acquired corrosion images, and benefits the quantitative evaluation of subsurface corrosion in aviation structures.