数字图像相关方法测量芳纶纤维复合材料I型裂纹应力强度因子

Evaluation of Mode I Stress Intensity Factor of Aramid Fiber Composite Materials Utilizing Digital Image Correlation Method

将数字图像相关方法用于芳纶纤维复合材料单边裂纹在拉伸载荷作用下的断裂问题研究。介绍数字图像相关方法的基本原理,建立数字图像相关方法中位移场与裂纹尖端应力强度因子之间的关系。通过搭建数字图像相关方法光学非接触测量系统,试验表征含单边裂纹芳纶纤维复合材料试验件在拉伸载荷作用下的全场位移。由数字图像相关方法所得位移场提取不同载荷作用下裂纹尖端应力强度因子,并分析最小二乘拟合项数、数字图像相关计算子区域和步长大小对计算结果的影响。结果表明,增加最小二乘拟合项次和合理选择数字图像相关计算子区域和步长大小可以提高应力强度因子计算精度。

Digital image correlation method was used to study the fracture performance of aramid fiber composites. The principle of the digital image correlation method was described, and the relation between the crack tip displacement and the stress intensity factor was deduced using least squares fitting. The optical measurement system of digital image correlation method was established, and the full field displacement of the single-edge crack specimen was obtained experimentally. The stress intensity factor was extracted from the dis- placement field, and the effects of the number of terms, subset size and subset spacing on the calculation results were analysed. The results show that increasing the number of least squares fitting terms and reasonable selection of digital image correlation subset size im- prove the accuracy of calculated stress intensity factor.