平板导体脉冲涡流场时域解与测厚特征量的提取  

Time-Domain Analytic Expressions for Pulsed Eddy Current Field of Conductive Plate and Characteristic Quantity for Thickness Measurement

作　　者：陈兴乐[1] 雷银照[1] 

机构地区：[1]北京航空航天大学自动化科学与电气工程学院,北京100191

出　　处：《电工技术学报》2013年第6期1-8,共8页Transactions of China Electrotechnical Society

摘　　要：本文求解了脉冲电流下降沿激励下平板导体涡流场时域模型,给出一种可测量板厚的信号特征量提取方法。利用拉普拉斯变换和有限汉克尔变换求解得到了截断涡流场模型在复频域中级数形式的场量表达式。利用留数定理求解拉普拉斯反变换,并利用电流对时间的导数与模型阶跃响应作卷积求解电流下降沿涡流场时域模型。给出了导体内涡流密度随时间的变化规律及其与感应电压之间的关系,并以有限厚平板导体与半无限大导体之间的感应电压差峰值时间作为特征量测量板厚。实验验证了解析式和测厚特征量的可靠性。This paper solves the pulsed eddy current field in time-domain of the conductive plate induced by falling current, and puts forward a way to obtain the signal characteristic quantity for thickness measurement. Through Laplace transformation and finite Hankel transformation, the series expansions for truncated eddy current field are attained in complex frequency-domain. The inverse Laplace transformation is figured out via residue theorem, and a new method is developed to calculate the eddy current field induced by falling current through the convolution between the time derivative of current and the unit step response of the model. The variations of the eddy current density in the conductor are studied and its relationship with induced voltage is presented. The thickness of the plate can be measured by using the peak time of the differential induced voltage between conductive plate and conducting half-space. Analytic expressions and characteristic quantity are verified through the experiments on aluminium plates.

关 键 词：脉冲涡流 时域解析式 测厚 涡流检测 电磁场理论 

分 类 号：TM15[电气工程—电工理论与新技术]