基于DBSCAN算法与GMM理论的铝合金板孔边疲劳裂纹萌生监测  

A Methodof Fatigue Crack Initiation-Monitoring at Hole Edge of Aluminum Alloy Plate Based on DBSCAN Algorithm and GMM Theory

作　　者：于翀 宋昊[1] 刘春红[1] 赵启迪 付佳豪 YU Chong;SONG Hao;LIU Chunhong;ZHAO Qidi;FU Jiahao(AVIC Changcheng Institute of Metrology&Measurement,Beijing 100095,China)

机构地区：[1]航空工业北京长城计量测试技术研究所,北京100095

出　　处：《空军工程大学学报》2024年第2期85-94,共10页Journal of Air Force Engineering University

基　　金：航空科学基金(20185644003)。

摘　　要：针对航空结构中多孔铝合金板在疲劳载荷作用下的孔边裂纹萌生监测问题,以光纤传感系统为基础结合小波分解、含噪声的密度空间聚类以及高斯混合模型,提出了一种孔边裂纹萌生监测方法。首先以光纤光栅传感系统采集循环加载条件下多孔铝合金板孔边裂纹萌生至结构断裂全程中孔边微应变并构建孔边微应变曲线。对孔边微应变曲线进行小波分解,得到微应变曲线的低频分量与高频分量,并以低频分量最小值及高频分量突变作为孔边裂纹萌生特征。在分析裂纹萌生时引入DBSCAN算法与GMM理论用于计算孔边裂纹萌生时的疲劳加载循环数并进行比较与分析得到多孔铝合金板孔边主裂纹的萌生位置以及孔边主裂纹裂纹萌生时的疲劳加载循环数。试验结果表明:此监测方法能够准确定位出孔边主裂纹的萌生位置,计算孔边主裂纹萌生时的疲劳加载循环数,且疲劳加载循环数计算误差在5%以内。在未来可应用于全机地面疲劳试验、结构健康监测等多种场景。In view of hole edge crack initiation-monitoring of porous aluminum alloy plates in aviation structures under fatigue load,a method of hole edge crack initiation-monitoring is proposed based on the fiber optic sensing system in combination with wavelet decomposition,density based spatial clustering of applications with noise and Gaussian mixture model.Firstly,a fiber optic grating sensing system is used to collect the micro strain at the edge of a porous aluminum alloy plate during the entire process from crack initiation to structural fracture under cyclic loading conditions,and a micro strain curve at the edge of the hole is constructed.Wavelet decomposition on the micro strain curve at the hole edge is performed to obtain the low-frequency and high-frequency components of the micro strain curve,and the minimum value of the low-frequency component and the sudden change of the high-frequency component are taken as the characteristics of crack initiation at the hole edge.The crack initiation being analyzed,the number of fatigue loading cyclic number is calculated by DBSCAN algorithm and GMM theory when the crack at the hole edge is initiated,and the initiation position of the main crack at the hole edge of the porous aluminum alloy plate and the number of fatigue loading cyclic number are compared and analyzed when the main crack at the hole edge is initiated.The test results show that this monitoring method is capable of accurately locating the initiation position of the main crack at the hole edge,and calculating the fatigue loading cyclic number when the main crack at the hole edge initiates,and the calculation error of the fatigue loading cyclic number is within the range of 5%.In the future,the method can be applied to the ground fatigue test of a whole-aircraft,structural health monitoring and other scenarios.

关 键 词：多孔铝合金板 光纤传感 孔边裂纹 裂纹萌生 DBSCAN算法 GMM理论 

分 类 号：V219[航空宇航科学与技术—航空宇航推进理论与工程]