A sensitivity enhancement PEC method for bottom flaws and corrosions detection

• Published in: Measurement : journal of the International Measurement Confederation 2022-10, Vol.202, p.111910, Article 111910
• Main Authors: Huang, Pu, Pu, Hang, Ding, Yiqing, Li, Zhengyong, Yin, Wuliang, Xu, Lijun, Xie, Yuedong
• Format: Article
• Language: English
• Subjects: Bottom flaws and corrosion detection; Frequency analysis; Gauss-pulse-modulation eddy current; Image processing technology; Sensitivity enhancement
• ISSN: 0263-2241; 1873-412X
• DOI: 10.1016/j.measurement.2022.111910

•The ETREE analytical solution is applied to analyze the response signal of PMEC and GPMEC.•The effect of carrier frequency and modulation frequency in PMEC is analyzed to obtain the optimal frequency.•The GPMEC excitation signal is investigated, which has higher sensitivity and noise immunity.•The image processing technology is proposed to determine the position of corrosion in C-scan image of GPMEC. Eddy current testing (ECT) is an efficient tool to detect the bottom flaw and corrosion because of its characteristics of non-contact, high sensitivity, and flexible. Compared with conventional ECT, the pulsed eddy current (PEC) testing applies instantaneous power to the measured object, thereby obtaining obvious transient response. In this paper, a novel Gauss-pulse-modulation eddy current (GPMEC) method is proposed to enhance the sensitivity of sensor. The energy excited by excitation coil is higher at the carrier frequency through frequency analysis. Correspondingly, an appropriate carrier frequency is chosen based on skin depth. Moreover, the Gauss window function acts on pulse-modulation signal to further increase the energy distribution. Following this, the experiments for bottom flaws and corrosions detection are carried out. The theoretical analysis and experimental results demonstrate that GPMEC is advantageous over than conventional PEC for bottom flaws detection.