扩展数字图像相关方法中裂尖位移函数的表征研究

探寻适用于扩展数字图像相关方法(X-DIC)的裂纹尖端位移函数,对于提高该方法在裂尖测试精度方面具有重要意义。本文基于断裂力学裂纹尖端位移场函数,进行主导项影响分析,并探究裂尖位移函数中各项及其组合项对位移场表征的贡献程度及对测试精度的影响。通过对I型、II型及混合型裂纹进行测试,发现各项及其组合项在不同裂纹类型测试中的影响有着较大区别,从而得出在X-DIC测试计算中影响裂尖位移场表征的主导项。最后,应用上述研究成果对某航空超硬铝合金的单边裂纹进行拉伸测试。

On the Characterization of Crack Tip Displacement Function in X-Digital Image Correlation Method

Searching crack tip displacement function suitably applied in extended digital image correlation method(X-DIC) is of great significance to improve the accuracy of this method in crack tip measurement. In this paper, based on crack tip displacement field function in fracture mechanics, the dominant term influence is analyzed, and the contribution of every terms and their combination in crack tip displacement field function to the characterization of displacement field and their effect on measurement accuracy of X-DIC method are analyzed. Through the measurement of type I, type II and mixed mode crack, it is found that every terms and their combination in crack tip displacement field function present large differences for different type crack tip measurement. Then the dominant term effecting the characterization of crack tip diaplacement field in X-DIC method is obtained. Finally, above results were applied to a single edge crack tensile test of super-dural umin alloys used in aviation.