基于涡流阵列传感器的金属结构疲劳裂纹监测

针对飞机金属螺栓连接结构疲劳裂纹实时监测的需求,提出了一种基于柔性平面涡流阵列传感器的飞机金属结构疲劳裂纹监测方案,通过半解析建模对传感器的工作特性进行了研究,搭建了监测系统并通过试验对方案可行性进行了验证.半解析模型结果表明传感器感应通道与激励通道的相位差和幅值比随提离距离及被测试件电导率的变化曲线具有单调性,且幅值比变化大,敏感度高.程序载荷谱作用下2A12-T4铝合金试件疲劳裂纹监测试验结果表明:将各通道幅值比变化曲线中的拐点作为特征点,传感器通道1能对累积损伤进行监测,通道2,3,4能对疲劳裂纹扩展长度进行定量监测,监测精度达到1 mm.所提出的柔性平面涡流阵列传感器能够实现对疲劳试件从累积损伤到疲劳裂纹扩展整个寿命周期的监测.

Fatigue crack monitoring of metallic structure based on eddy current array sensor

To monitor the fatigue crack of aircraft metallic structure in real-time, a scheme for fatigue crack monitoring of aircraft metallic structure based on flexible planar eddy current array sensor is put forward. The characteristics of sensor were analyzed via semi-analytic model, and feasibility of scheme was verified through monitoring experiment based on constructed fatigue crack monitoring system. The result of semi-analytic model shows that the curves of phase difference and amplitude ratio between sensing channel and driving channel varying by lift-off and the conductivity of material under test have singularity and the amplitude ratio changes greatly. The result of fatigue crack monitoring experiment of 2A12-T4 aluminum alloy under constant load indicates that the first channel of sensor is capable of monitoring on accumulated damage and the other three channels are capable of quantitative monitoring on fatigue crack, with monitoring precision of 1mm. The proposed flexible planar eddy current array sensor achieves the whole lift cycle monitoring of specimen from accumulated damage to fatigue crack propagation.