中文摘要：

以厚壁铁磁性材料为对象,研究了基于晚期信号斜率的脉冲涡流测厚方法。首先分析了铁磁性材料脉冲涡流时域信号的特点,得出峰值、峰值时间、过零点、提离交叉点等特征量难以适用的结论。然后将感应电压信号从直角坐标系转换到单对数坐标系,针对单对数坐标系下晚期信号趋于直线且直线斜率与材料厚度一一对应的特征,提出以信号斜率为特征量的脉冲涡流信号分析方法。最后开发了实验系统,运用该方法在16MnR阶梯钢板上进行了实际测量。实验结果表明,该方法能有效地用于铁磁性材料的厚度检测,检测范围大,壁厚误差小于5%,且不受提离影响。

英文摘要：

Thickness measurement of thick-wall ferromagnetic materials using pulsed eddy current（PEC） technology was studied based on the feature of late signal slopes.At first,time domain features of the ferromagnetic material PEC signals are analyzed in time domain,which indicates that the common features such as peak value,time to peak value,time to zero crossing and point of lift-off intersection are difficult to apply.So,we switch the Cartesian coordinate system to the semi-logarithmic coordinate system;and use the characteristic that in the semi-logarithmic coordinate system,the late signal tends to a straight line and the straight-line slope corresponds with the thickness of the test specimen.A new feature based on the late signal slopes is extracted to analyze the PEC signals.Finally,experiments were carried out on a 16MnR steel step wedge to verify this method.Experiment results show that this method can be effectively used to measure the thickness of ferromagnetic materials with large detection range,small relative error（less than 5%） and independence of lift-off.