贴附式涡流传感器损伤监测特性仿真与实验研究

Characteristic Simulation and Experiment Study of Attached Eddy Current Sensor on Crack Monitoring

为满足飞机结构裂纹扩展定量化监测和工程化应用的需求，探索MWM（Meandering Winding Magnetometer）传感器进行结构健康监控的可行性，设计了一种贴附式涡流阵列传感器并为传感器的工程化应用开展了仿真优化和实验研究。基于裂纹扩展分段监测的思路，传感器的感应线圈和激励线圈采用阵列化设计。通过将材料的电导率提取为结构的等效损伤参数，构建了传感器损伤监测正向半解析模型，并对线圈厚度和基材层厚度进行了优化。为验证传感器的监测能力，开展了程序载荷谱下的2A12-T4铝合金阳极氧化试件的疲劳裂纹扩展监测实验。仿真优化结果表明，传感器监测灵敏度随提离距离的增加而减小，传感器最优工作频率范围为0.3-0.7MHz。裂纹扩展监测实验结果表明，贴附式涡流传感器具备对金属结构进行实时损伤监测的能力，感应线圈的阵列化布置方式实现了裂纹扩展的定量监测，精度达到毫米级，同断口分析结果相比，平均监测误差为3.85%。

To monitor the crack extension quantitatively in real time and to explore the feasibility of MWM （Meandering Winding Magnetometer）for structure health monitoring,a kind of attached eddy current sensor was put forward and characteristic simulation was carried out as well as experimental study. According to the idea of segmented monitoring the crack,the excitation coils and induction coils of the sensor were arranged in an array. By exacting material’s conductivity as the damage feature,forward semi-analytical model was built and optimizations on thickness of coil were carried out as well as thickness of the substrate layer. In order to verify the sensor performance,crack extension experiment on 2A12-T4 aluminum alloy under the programmed load spectrum was conducted. The results show that the sensitivity decreases with the increase of liftoff,and the optimal working frequency ranges from 0.3MHz to 0.7MHz. The experiment indicates that the sensor is capable of monitoring the crack in real-time and the arrayed arrangement of induction coils allows to measure the crack quantitatively with the accuracy to millimeter. The general error is 3.85%compared with the result of fracture analysis.