面扫描模式下的涡流热成像缺陷重构方法研究

Defect Reconstruction Method of Eddy Current Thermal Imaging in Dynamically Detecting Mode of Plane Scan

为有效检测海上平台结构损伤,评定结构的安全性和可靠性,提出一种基于面扫描动态检测模式下的涡流热成像缺陷重构方法。研究了涡流热成像的加热过程,并将加热过程进行分阶段分析;采用面扫描方法提高信息采集的完整性及扫描速率,生成检测区域的热图像序列,并定位目标区域(缺陷位置);提取特定加热阶段的温度进行分析,对缺陷的轮廓范围及深度尺寸分别进行研究,将两者相结合,最终利用神经网络对缺陷进行重构,再将结果与缺陷的真实尺寸进行对比,可以反映出该重构方法的实际效果。试验结果表明,基于面扫描动态检测模式下的涡流热成像缺陷重构方法对缺陷长度及深度的重构效果较好,对缺陷宽度检测效果不佳,主要原因是缺陷宽度尺寸较小,试件表面热传导效应对检测结果影响较大。研究结果可为海上平台结构损伤检测方法的研究提供一定的指导。

In order to effectively detect the structural damage of offshore platforms and evaluate the safety and reliability of structures,a defect reconstruction method based on eddy current thermal imaging in dynamically detecting mode of plane scan was proposed.The heating process of eddy current thermal imaging was analyzed in stages.Plane scanning was adopted to improve the integrity and scanning rate of information collection.The thermal imaging sequences for the detection area were generated and the target area(defect area)was located.The temperatures of the specific heating stage were picked up for analysis,and the profile and depth of the defect area were studied respectively.By combining them,the defect area was reconstructed.The test results show that,this defect reconstruction method based on eddy current thermal imaging in dynamically detection mode of plane scan could obtain good results in the construction of length and depth of the defect area,but the width of the defect area could not be detected accurately.This is mainly because the small width of defect area is significantly influenced by the surface heat conduction effect of the test piece.The research results could provide some guidance for the research of structural damage detection methods of offshore platforms.