基于平面电容传感器的复合材料缺陷检测研究

Research on composite defect detection based on planar capacitance sensor

为实现利用平面电容传感器直接测得的电容值对碳纤维增强复合材料(CFRP)缺陷的表征,本文基于电容边缘效应,在有限元仿真软件COMSOL中构建平面电容传感器,分析电极参数对其性能的影响并进行优化,灵敏度提高2%~52%,穿透深度可达到4.13 mm。当传感器的面积一定时,研究感应电极的最优长宽比,并拟合得出传感器电极长度与面积之间的线性关系。在单电极直流激励的情况下,改变缺陷大小,检测感应电极的电容值变化。结果表明随着缺陷大小的增加,感应电极的电容值会随之减小,利用拟合曲线可以实现对CFRP缺陷的量化评估,其相关系数达到0.996以上。

In order to characterize the defects of carbon fiber reinforced plastics(CFRP) by using the capacitance directly measured by planar capacitance sensor, a planar capacitance sensor is constructed in COMSOL based on the capacitance edge effect, and the influence of electrode parameters on its performance was analyzed and optimized, The sensitivity has been improved by 2%~52%, and the penetration depth can reach 4.13 mm. When the sensor area is constant, we can find the optimal length to width ratio of the sensing electrode, and then we can fit the linear relationship between the electrode length and area. The change in the capacitance value of the sensing electrode is detected when the defect size is varied with a single electrode DC excitation. The results show that the capacitance value of the sensing electrode decreases as the defect size increases, and the quantitative evaluation of CFRP defects can be achieved using the fitted curve with a correlation coefficient of 0.996 or more.