Features extraction of sensor array based PMFL technology for detection of rail cracks

Pulsed magnetic flux leakage (PMFL) testing is a new emerging and effective electromagnetic non-destructive testing (NDT) technology which combines the conventional magnetic flux leakage (MFL) technology with the theory of pulsed current. Compared with single sensor, the sensor array can scan larger areas with higher speed and lower lapsus. Finite element method (FEM) is used to get the ideal signal of MFL with defects, including signal horizontal and vertical. According to the analysis of different signal of MFL with defects, the relation between magnetic signal and defect size is received. Then a full set of PMFL system based on sensor array is used to detect the standard specimens. In order to eliminate the noise and extract the feature, the detecting signal is analyzed and processed by some pre-treatments. In the process of time-domain analysis, every peak value of sensor signal is extracted as analyzing signal, then peak values are lined as output signal of the sensor array. By analyzing different characters of curve under different defect sizes, and getting corresponding characteristic quantities, the reasons of the errors are discussed. (C) 2013 Elsevier Ltd. All rights reserved.