数字图像相关方法在A508-3钢J积分测试中的应用

Application of digital image correlation method in J-integral test of A508-3 Steel

J积分作为评定韧性金属材料结构安全性的基本数据在断裂力学实验中有着大量的应用,但目前对J积分测试中关键数据裂纹增量Δa的测量经常出现随实验力的增加,裂纹发生"负增长"的现象,且对加载过程中转动中心的定位存在偏差,导致修正公式不准确.为提升J积分测试准确性,应用数字图像相关方法对A508-3钢的紧凑拉伸试样在J积分测试实验过程中的全场变形情况进行分析,确定其加载过程中裂纹面转动中心的位置,并利用数字图像相关方法代替柔度法对裂纹增量Δa进行了测量,计算得到了A508-3钢的JR曲线.

J-integral has a large number of applications in fracture mechanics experiments as basic data for assessing the structural safety of ductile metal materials.However,the negative crack extension often happens in the measurement of the crack increment in the J-integral test,and the modified formula is inaccurate due to the deflection of rotation center of crack surface.To improve the accuracy of the J-integral test,digital image correlation method was used in this paper to analyze the full field deformation situation of the compact tensile specimen of A508-3 steel,and the position of the rotation center of crack surface of the CT samples during the loading process was determined.The crack increment was also measured by digital image correlation method instead of the compliance method.The J R curve of A508-3 steel were calculated at the same time.