三维数字图像相关变形测量结果的一致性研究与校验

Consistency research and verification of results of 3D digital image correlation deformation measurement

采用典型四点弯实验对规范测试条件下三维数字图像相关(3D-DIC)变形测量结果的一致性进行了研究,并采用溯源于激光波长的电子散斑干涉(ESPI)计量检测技术对其离面位移测量结果进行校验。结果表明,在规范测试条件下,当相机分辨率为2048pixel×2048pixel时,3D-DIC的应变测试误差在50με以下,当变形大于1000με时,标准离差率始终处于0.05以下。计量检定结果表明,在采用规定的数字散斑图案、规范操作步骤及计算参数的情况下,采用电动位移计对悬臂梁进行加载,位移为0~10μm时,60mm视场3D-DIC系统测量误差不超过0.25μm。综合上述结果表明,通过规范操作步骤及计算方法等因素,能够保证数字图像相关方法在变形测试时的精度,且结果具有良好的一致性。

The consistency of three-dimensional digital image correlation(3 D-DIC) deformation measurement under standard testing conditions was studied by using typical four-point bending experiments, and the out-of-plane displacement measurements were verified by using electronic speckle interference(ESPI) measurement technology tracing to laser wavelength. The results show that under standard test conditions, when the camera resolution is 2048 pixel×2048 pixel, the strain test error of 3 D-DIC is below 50με, and when the deformation is greater than 1000με, the standard deviation is always below 0.05. The metrological verification results show that under the condition of the specified digital speckle pattern, standard operation steps and calculation parameters, the cantilever beam is loaded by an electric displacement meter, and the measurement error of the 3 D-DIC system does not exceed 0.25μm when the displacement range of the cantilever beam is 0~10 μm and the field of view is 60 mm. The above results show that the accuracy of digital image correlation method in deformation test can be guaranteed by standardizing the operation steps and calculation methods, and the results have good consistency.