一种裂纹识别方法的研究及试验验证

Research on the Method of Crack Identification and Experimental Verfication

本文基于数字图像相关法研究了裂纹识别技术。首先介绍了基于位移场的裂纹识别算法的基本原理,建立了对目标函数进行迭代优化的粗细搜索法,然后在模拟位移场数据上添加不同强度的噪声来验证该算法的鲁棒性,接着设计了CCT试件并进行了裂纹扩展试验,在整个裂纹扩展过程中利用裂纹识别技术对裂纹进行了监测,得到了裂纹长度和应力强度因子。结果表明,裂纹识别技术受噪声的影响很小,能够准确获得裂纹扩展试验的裂纹信息。该研究对飞机结构损伤容限试验中的裂纹自动测量的实现具有较高的指导价值和参考意义。

This paper focuses on a method of crack identification based on digital image correlation method. Firstly,the basic principles of crack identification method are introduced and a coarse-fine search method which is used for optimizing the objective function iteratively is established. Then different intensity noises are added on simulated displacement field to verity the robustness of this method. Then center cracked tension specimen and crack propagation test are designed. Crack identification method is used to monitor the crack throughout the test process.Crack length and stress intensity factor are obtained. The results show that this method has little effect by the noise and can exactly get the crack information during crack propagation process. This study has a high engineering value for the realization of automatic crack measurement in the aircraft structure damage tolerance experiment.