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Yang Wang published “Frequency Domain Analysis of Magnetic Field Images Obtained Using TMR Array Sensors for Subsurface Defect Detection and Quantification” on NDT&E

Release time:2020-08-15
Chaofeng Ye, Yang Wang, Meiling Wang published “Frequency Domain Analysis of Magnetic Field Images Obtained Using TMR Array Sensors for Subsurface Defect Detection and Quantification” on NDT&E in April, 2020. In this paper, a new ECT method for subsurface defect detection and quantification is proposed. Eddy currents with continuously varying frequency in a selected frequency band is induced in the conductive sample by using a chirp modulated excitation scheme. The footprint of the defect is calculated using spatial features of the C-scan image while the depth of the defect is estimated by analyzing the frequency characteristics of the measured chirp signal. A three-dimensional estimate of the dimensions of any subsurface defect can be obtained using the empirical procedure. An aluminum sample with embedded defects was tested using the prototype probe. It is seen that the proposed scheme utilizing spatial and frequency domain features is capable of quantitatively characterizing subsurface defects.