基于虚拟示波器的涡流应力测量装置研制

为将涡流阻抗法应用于金属构件应力的快速测量,基于改进的矢量伏安法,采用虚拟示波器技术,研制出一套测量参数可控的便携式阻抗测量装置。实验测试了信号平均次数、电路采样电阻等对涡流传感器阻抗-频率特性曲线测量精度的影响规律,在优化参数条件下,研制的阻抗测量装置与Agilent 4294a的测试结果较为一致,相对偏差在±5%范围。将便携式装置应用于金属杆件的涡流应力测量:先后对45号钢杆和LY12铝合金直杆进行拉伸实验,测量粘贴于直杆上涡流传感器的阻抗变化,回归分析得到阻抗变化率与拉力的直线拟合方程(拟合优度大于0.9)。实验结果表明,基于虚拟示波器的阻抗测量装置可以基于涡流测力原理,实现金属构件应力的快速、有效测量。

Virtual oscilloscope technique based device for stress measurement using eddy current method

In order to apply the eddy current impedance method to the fast stress measurement of metal component, based on the improved vector voltammetry method, a portable impedance measuring device with controllable measurement parameters is developed using virtual oscilloscope technology. The influence of the average number of signals and the circuit sampling resistance on the measurement accuracy of the impedance frequency characteristic curve of the eddy current sensor is studied in experiments; under the optimized parameters, the test result of the developed impedance measuring device and that of the 4294A from Agilent are quite consistent, and the relative deviation is in the range of 5%. The portable device was applied to the eddy current stress measurement of metal bars; the tensile tests on No. 45 steel and LY12 aluminum alloy straight bars were conducted, respectively; the impedance variation of the eddy current sensor adhered on the straight bars was measured, and the linear fitting equation of the impedance change rate vs. the pulling force was obtained with regression analysis (the fitting goodness is greater than 0.9). The result shows that the virtual oscilloscope technique based impedance measuring device can achieve fast and effective measurement of the stress of metal components based on the principle of eddy current detection.