基于光纤布拉格光栅阵列的铝合金疲劳裂纹预测方法  

Fatigue Crack Prediction Method for Aluminum Alloy Based on Fiber Bragg Grating Array

作　　者：孙玲玉 刘长超 姜明顺[1] 张雷[1] 张法业[1] 隋青美[1] 贾磊[1] Sun Lingyu;Liu Changchao;Jiang Mingshun;Zhang Lei;Zhang Faye;Sui Qingmei;Jia Lei(School of Control Science and Engineering,Shandong University,Jinan,Shandong 250061,China)

机构地区：[1]山东大学控制科学与工程学院,山东济南250061

出　　处：《中国激光》2021年第13期155-165,共11页Chinese Journal of Lasers

基　　金：国家重点研发计划(2018YFE02013);国家自然科学基金(62073193,61903224,61873333);山东省重点研发计划(2019TSLH0301,2019GHZ004)。

摘　　要：针对铝合金结构服役过程中的疲劳裂纹监测问题,提出了一种基于光纤光栅传感阵列的疲劳裂纹实时监测方法。首先,结合扩展有限元技术获得裂纹扩展过程的应变场分布特征,进行传感器布局设计;其次,通过疲劳加载实验获取加载次数、裂纹长度对波长峰峰值的响应特征,采用三参数指数法进行疲劳扩展a-N(其中N为加载次数,a为裂纹长度)曲线拟合;在实验数据基础上,采用梯度提升回归树算法搭建疲劳损伤预测模型,并将其与线性回归、支持向量两种方法进行对比,选取可释方差、平均绝对误差、平均方差、决定系数和五折交叉验证等多种指标进行模型评估。结果表明,梯度提升回归树算法对疲劳裂纹长度的预测效果最佳。Objective Under the action of long-term fatigue loading, the metal structures of the spacecraft, high-speed train, ship, and other large equipment are prone to fatigue crack in the stress concentrated part. Under the repeated action of alternating loading, the structure will be further extended, resulting in failure and fracture, causing major production safety hazards. In the fatigue crack monitoring field, the commonly used technical means are sound emission, ultrasonic guided wave, and strain monitoring. With the development of strain sensors, the strain monitoring method plays an important role in fatigue crack identification and life monitoring. Among them, the fiber Bragg grating(FBG) sensor is characterized by high precision, sensitivity, stability, and portability along with long monitoring range, promoting further development of strain monitoring technology toward higher accuracy, higher sensitivity, higher reliability, and better convenience. In this paper, a real-time continuous crack monitoring method based on the FBG sensor array is proposed for the fatigue crack monitoring of aluminum alloy structures in service.Methods The research method of this paper is shown in a flow chart(Fig.1),which is mainly divided into the following four parts:parameter selection,experiment and data processing,prediction and evaluation,and model building.First,fatigue loading test parameters and crack-propagation characteristics are obtained via tensile tests.The strain field distribution characteristics during crack propagation are obtained via extended finite element simulation.Based on the strain field analysis and fatigue loading experiment results of different crack-propagation stages,a reasonable layout of the FBG sensor array is designed.Through fatigue loading and strain monitoring experiments,the relationships among fatigue loading times,wavelength response,and crack length are obtained.Values of peak-peak wavelength are extracted as characteristic values to exclude the interference of temperature and deformation

关 键 词：光纤光学 光纤光栅 疲劳裂纹 扩展有限元 梯度提升回归树 裂纹预测 

分 类 号：TP212[自动化与计算机技术—检测技术与自动化装置]