建立了基于三维数字图像相关（3D-DIC）的非接触光学测试系统，对2A12铝合金弹性常数进行了测试，在此基础上分析了DIC子区和步长的大小对材料弹性常数测试结果的影响，并探讨了2A12铝合金在拉伸载荷作用下的变形演化规律。结果表明：3组2A12铝合金试样测得的弹性模量和泊松比分别为66.32，67.51，63.08 GPa和0.333，0.336，0.347；改变子区大小将引起图像噪音的变化，对测试结果的影响较改变步长的影响更为明显，步长则主要作用于DIC算法的运行时间；2A12铝合金试样在整个拉伸过程中依次经过弹性变形、均匀塑性流动以及应变局部化三个阶段后发生断裂。

Non-contact optical measurement system based on three-dimensional digital image correlation (3D-DIC) was established to test the elastic constants of 2A12 aluminum alloy. The effects of different sizes of DIC parameters, i.e. subset size and step size, on the elastic constant test results of the material were investigated, and the deformation evolution law of 2A12 aluminum alloy under the action of tensile load was also discussed. The results show that the elastic modulus and Poisson ratio of three groups of 2A12 aluminum alloy specimens were 66.32, 67.51, 63.08 GPa and 0.333, 0.336, 0.347, respectively. Changing the subset size caused the change of image noise, subset size had more influence on the test results compared to step size, and step size mainly controlled the computational time of DIC algorithm. The 2A12 aluminum alloy specimen fractured after three stages of elastic deformation, uniform plastic flow and strain localization.