超低温DIC全场微应变测量精度提高方法

Methods to Improve the Precision of Strain Fields at Cryogenic Temperature Based on Digital Image Correlation

数字图像相关技术在非均质焊接接头的力学性能研究方面具有独特的优势,但低温介质气化引起的气流扰动、起雾、结霜以及低温引起光学玻璃的厚度和折射率发生改变均会对图像产生较大影响,是DIC测试系统的误差的主要来源。本文分析了超低温环境下DIC全场微应变测量误差的影响因素,掌握超低温环境下的光测力学误差产生的机理,提出了DIC全场微应变测量精度提高方法,将超低温环境DIC全场微应变测量精度提高45倍,对准确获取贮箱焊缝结构在低温环境下全场力学性能,提高焊接结构性能,保证焊接结构安全性和可靠性具有重要的意义。

Digital image correlation(DIC)has unique advantages in studying the mechanical properties of heterogeneous welded joints,but the thermal flow disturbance,fogging,frosting caused by low-temperature medium gasification and the changes in the thickness and refractive index of optical glass caused by low-temperature will have a great impact on the image,which are the main sources of errors in the DIC testing system.The influencing factors of the measurement error of cryogenic temperature strain fields based on DIC were analyzed,and the mechanisms of DIC strain measurement’s error in cryogenic temperature were grasped in this paper.Methods to improve the precision of cryogenic temperature strain fields were proposed.The experimental results showed that the precision was improved by 45 times.The technical achievements have important significance to accurately obtain the full field mechanical properties,improve the performance and ensure the safety and reliability of the welding structures in the cryogenic temperature environment.