基于平衡电磁技术的管道裂纹全角度检测方法

针对管道表面裂纹缺陷方向各异的问题,提出一种基于平衡电磁技术的裂纹全角度检测方法。通过麦克斯韦方程分析了时谐电磁场下管道内表面的电磁分布,根据磁通与感应电流的畸变分析了管道表面各方向裂纹的检测机理与检测信号规律,并证明了平衡电磁技术对管道裂纹全角度检测的有效性。利用有限元方法计算分析了裂纹与检测方向成七种不同角度时管道内表面的电磁畸变程度,并通过仿真得到相应的感应电压信号,根据仿真结果进行有效性试验,结果表明,平衡电磁检测技术能够对管道表面裂纹实现全角度检测,检测信号特征以检测方向与裂纹成30°夹角为分界,0°～30°信号特征为先波谷后波峰,检测信号幅度随着角度增加逐渐减小,峰谷间距快速变小;30°～90°信号特征为先波峰后波谷,检测信号幅度随着角度增加逐渐增大,峰谷间距缓慢变小;当检测方向与裂纹成30°时,感应电压信号为双峰谷特征,且峰峰值最小。该方法为管道表面裂纹角度的量化研究提供了理论依据和实验基础。

Full-angle detection method of pipeline crack based on balancedelectromagnetic technology

Aiming at the problem of different directions of erack defects on the surface of the pipeline, a crack detection method based onbalaneed electromagnetie technology is proposed. The eleetromagnetie distribution of the inmer surface of the pipeline under the time-harmonic electromagnetic field is analyzed by Maxwell''s equations. According to the distortion of magnetie flux and induced current, thedeteetion mechanism and signal law of eracks in all directions on the pipeline surface are analyzed, and the effectiveness of the balancedeleetromagnetie technology for all angle detection of pipeline cracks is proved. The finite element method is used to caleulate and analyzethe electromagnetie distortion degree of the inner surface of the pipeline when the crack is at seven diferent angles to the detectiondirection, and the corresponding induced voltage signal is obtained through simulation, Aceording to the simulation result, the validitytest is carried out. Results show that the balaneed eleectromagnetie deteetion technology can realize the full angle detection of the surfaceerack of the pipeline. The deteetion signal feature is divided by the detection direction and the crack at an angle of 30°. The 0°~30°signal feature is the first trough followed by the peak. The amplitude of the detection signal gradually decreases as the angle increases,and the peak-to-valley spacing decrease rapidly, 30°~90° signal features a peak first and then a trough. The amplitude of the deteetionsignal gradually inereases as the angle inereases, and the peak-to-valley spacing slowly decreases; when the detection direction is 30°t0the crack, the indueed voltage signal has a double peak-valley feature, And the peak-to-peak value is the smallest. This method providesa theoretical basis and experimental hasis for the quantitative study of the erack angle on the pipe surface.