Most of existing crack monitoring methods have disadvantages in terms of poor durability and high false alarm probability.A scheme for improving the durability of the Physical Vapor Deposition (PVD) film sensor is proposed,and the performance of crack monitoring of the sensor in coupled environment is tested.First,Cu Is selected as the depositing material of the conductive sensing layer to make the best durability of the film sensor,and the ion plating AIN film and coated 705 silica gel are used to package the PVD film sensor.Second,with comprehensive consideration of service environment,the periodic accelerated environment spectrum is compiled,and the packaged PVD film sensor deposited on the substrate is tested in this spectrum.Finally,fatigue crack monitoring of the post-environment-test specimen is carried out,and the results of film sensor monitoring are compared with those observed from the microscope.Comparison results show that the film sensor is able to endure the test of 1000 h in adverse environment conditions,so it has relatively high durability and stability.The post-environment-test film sensor is sensitive to crack development,and the result of PVD film sensor monitoring consists with measured crack development information.The potential monitoring signal of the PVD sensor can be used as the judging criteria of the crack stage and structural damage extent,and the PVD film sensor can realize quantitative monitoring of the fatigue crack with precision reaching 1 mm.%现有裂纹监测技术多存在耐久性差、虚警率高的问题.以物理气相沉积(PVD)薄膜传感器为研究对象,提出了提高其耐久性的方案,并检验了其在耦合服役环境下的监测性能.首先,选定了Cu作为使传感器耐久性最佳的导电传感层沉积材料,并采用离子镀氮化铝(AlN)薄膜和涂覆705硅胶对PVD薄膜传感器进行了封装保护;然后,综合考虑服役环境因素,编制加速环境谱,将经过封装的制备有薄膜传感器的试验件进行环境耦合加速试验;最后,对环境试验后的薄膜传感器开展疲劳裂纹监测试验,并将薄膜传感器监测结果与显微镜观察测量结果进行对比.试验结果表明:薄膜传感器能承受1 000 h严酷环境的考验,具有较高的耐久性和稳定性;环境试验后的薄膜传感器对裂纹变化敏感,PVD薄膜传感器的监测结果与基体裂纹扩展的实测信息相一致,PVD薄膜传感器的电位监测信号可以作为裂纹扩展状态和结构损伤程度的监测判据,PVD薄膜传感器可以实现对金属结构裂纹的定量监测,监测精度可达到1 mm.
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