相轨迹电涡流无损检测方法及频率响应特性研究  

Study on frequency response characteristics of the eddy current non-destructive testing method based on the phase trajectory

作　　者：张牧[1] 刘珊[1] 张荣华[1] 王化祥[2] 柳干[1] 

机构地区：[1]天津工业大学电气工程与自动化学院,天津300387 [2]天津大学电气与自动化工程学院,天津300072

出　　处：《仪器仪表学报》2016年第10期2267-2273,共7页Chinese Journal of Scientific Instrument

基　　金：国家自然科学基金青年科学基金(61402330);高等学校博士点专项科研基金(20131201120002);天津市高等学校科技发展基金(20140727)项目资助

摘　　要：基于电磁涡流检测的变压器等效理论,研究了激励频率对电涡流等效变压器模型中各参数的影响。对不同频率正弦激励下空间磁通密度法相分量B_z信号进行相敏解调,并绘制其相轨迹图。仿真及实验结果表明,在不同频率的电流激励下,B_z的相轨迹最大值点所处位置相同.在该最大值点处,单一频率激励下B_z的相轨迹均呈现较好的线性度。而当激励频率变化时,相轨迹的斜率k_B呈现出高维度的变化规律,利用多项式拟合方法对k_B=f(ω)进行最小二乘拟合后发现,被测材料表面及内部缺陷均会对k_B=f(ω)的模型产生影响,表面缺陷对高频部分影响更明显,而内部缺陷使低频部分的变化更大。利用这一结论可有效识别缺陷深度,且该方法实现了对提离噪声的抑制。The effect of excitation frequency on parameters of the equivalent transformer model is investigated based on the transformer equivalent theory for eddy current detection.The signals of Bz,the normal component of the space magnetic flux density,under sinusoidal excitations with various frequencies are phase-sensitively demodulated.The phase trajectories of them are drawn.The simulation and experimental results show that the positions of the maximum points in the phase trajectories of Bz under excitations with various frequencies are the same.The phase trajectory of Bz under the single frequency excitation is linear.kB ,the slope of the phase trajectory,changes with the high dimension if the excitation frequency changes.The change trend is expressed as kB =f（ω）.The least square fit is carried out to with the method of Polynomial fitting.The fitting result shows that both the surface and inner defects of the tested material affect the model of f（ω）.The surface defects mainly affect the high frequency part compared with the low frequency part which is mainly influenced by the inner defects.The method can be used to effectively identify the depth of defects,and the lift off noise can be suppressed.

关 键 词：涡流检测 相敏解调 变压器等效电路 多频激励 提离高度 

分 类 号：TH701[机械工程—仪器科学与技术]