基于饱和低频涡流检测技术的管道内外缺陷识别方法仿真

Simulation of Pipeline Inner and Outer Defect Recognition Based on Saturated Low Frequency Eddy Current Technique

管道检测中,由于集肤效应的限制,常规涡流检测技术很难对深层缺陷进行检测。通过外加直流磁化场,使用饱和低频涡流技术(SLFEC)将被测工件磁化至饱和状态,可降低其相对磁导率进而增加集肤层厚度,提高检测深度。基于饱和低频涡流检测技术原理,采用有限元方法构建饱和低频涡流检测技术仿真模型。仿真表明,SLFEC技术对壁厚30 mm管道不同埋深裂纹和管道内外腐蚀缺陷均具有较好的检测效果,同时采用阻抗分析法可较好地区分管道不同埋深裂纹和内外腐蚀。

Eddy current testing （ECT） is a normally used nondestructive testing method. However, because of the skin effect, it is difficult to detect the deeper defects by ECT. Using saturated low frequency eddy current technique （SLFECT）, the structure is magnetized to saturation by adding a direct magnetizing field; in addition, the relative permeability is decreased and the skin effect is reduced. In this paper, based on the thesis of SLFECT, the model of SLFECT is built by finite element method. The simulation results indicate that the crack in different depth, inner and outer corrosions can be detected obviously; moreover, using the impedance analysis method, the depth of crack and position of corrosion can be recognized.