关键词: 较厚钢板, 大电流脉冲, 小波滤噪, 幅值归一化

Abstract:

In order to detect the defects on thicker steel plate, a high-current pulse was needed, which was generated by chopping the low-voltage high power supply. Moreover, cylindrical probe was designed to detect surface defects of steel plate by slow discharging of exciting coil; rectangular probe was also designed to detect sub-surface defects of steel plate by instant discharging of exciting coil. Then the transient induced voltage signal of pulsed eddy current was processed by the wavelet filtering and amplitude normalization. Experimental results show that the wavelet filtering can improve detecting accuracy and the signals amplitude normalized can reflect the relationship of the defect curves at different depths defects more directly. It is concluded that amplitude of high pulsed eddy current signal excited by high-current can reflect the depths of defects on surface and sub-surface of thicker steel plate effectively.

Key words: thicker steel plate, high-current pulse, wavelet filtering, amplitude normalization