PVD薄膜传感器裂纹检测概率测定与分析

Estimation and analysis of probability of PVD film sensor crack detection

为利用PVD(physical vapor deposition)薄膜传感器对金属结构裂纹的检测能力进行定量化表征,首先采用正交实验优化后适用于LY12-CZ铝合金的工艺参数,在3组中心孔板实验件上分别制备币状、1mm宽同心双环状、0.5mm宽同心三环状3种不同形状的PVD薄膜传感器。随后,在实验室条件下开展疲劳裂纹在线监测实验,对比分析PVD薄膜传感器电位输出信号和显微镜观测结果。最后,采用改进的裂纹尺寸间隔法和二项分布检测模型绘制PVD薄膜传感器总体与不同形状的裂纹检测概率曲线。PVD薄膜传感器在95%置信水平下,对长度大于0.99mm的裂纹检出概率可达93.56%;相比于币状薄膜传感器,同心环状薄膜传感器对小于0.5mm的裂纹更为敏感,且传感器通道宽度越细,对小尺寸裂纹的检测概率越高。

In order to quantitatively characterize the ability of PVD(physical vapor deposition) film sensors to detect cracks in metallic structures, the process parameters applied to LY12-CZ aluminium alloys were first optimized using orthogonal tests, and coin shape, 1mm concentric dual ring shape, 0.5mm concentric tricyclic shape PVD film sensors were prepared on three groups of specimen with central hole using these parameters. Subsequently, the on-line monitoring experiment of fatigue cracks was carried out under laboratory conditions, the potential output signals of the PVD film sensors and microscope observations were compared and analysed. Finally, the probability of detection curves of all kinds of PVD thin-film sensors and PVD film sensor in different shapes were plotted separately using the improved crack size separation method and binomial distribution detection model. PVD thin-film sensors have 93.56% detection probability for cracks with length greater than 0.99mm at 95% confidence level. Compared to coin-shaped thin-film sensors, concentric ring shape film sensors are more sensitive to cracks smaller than 0.5mm, and the sensors with finer channel width have the higher probability of detection on small size cracks.