基于涡流脉冲热成像的角焊缝表面裂纹检测北大核心CSCD

角焊缝裂纹是焊接结构中常见的缺陷之一,由于其所处位置特殊而常出现漏检、错检等情况。本文采用涡流脉冲热成像技术对T形角焊缝裂纹进行了研究,并提出了一种包含表面裂纹热图像前、后处理及定量检测的检验方法。首先,采用L形铁氧体磁芯对角焊缝缺陷试件进行检测,然后基于独立成分分析算法(ICA)对整个图像序列进行前处理,并提出了一种改进区域生长算法用于提取缺陷特征,最后利用所提出的检测方法对缺陷进行了定量检测和误差分析。实验结果表明,所提出的检测方法可以实现对焊缝表面裂纹的检测,抑制不均匀加热和边缘效应,改善图像分割中的欠分割和过分割现象,且检测出的缺陷长度和宽度相对误差仅为0.4%和14%。

Surface crack detection of fillet weld based on eddy current pulse thermography

Fillet weld crack is one of common defects in welding structure,due to its special position,missing and false detection often occurs.In this paper,eddy current pulse thermography technology is used to detect the cracks of T shaped fillet weld,and a detection method including the thermal image pre processing,post processing and quantitative detection of surface crack is proposed.Firstly,the L shaped ferrite core is employed to detect the weld defect specimen,then the whole image sequence is pre processed based on independent component analysis(ICA)algorithm.Second,an improved region growth algorithm is proposed to extract defect features.Finally,the proposed detection method is used for quantitative detection and error analysis of the defects.The experimental results show that the proposed detection method can detect the weld surface crack,suppress the uneven heating and edge effect,improve the under segmentation and over segmentation in image segmentation,and the relative errors of defect length and width are only 0.4% and 14%.