Effect of Subset Size and Gage Length for Measurement Accuracy in Digital Image Correlation

The measurement accuracy and the spatial resolution of displacements and strains by digital image correlation method (DIC) is investigated. Displacements of the in-plane rigid body rotation are measured by DIC using various subset sizes. Displacement gradients are calculated using local least squares method with various gage lengths. Standard deviations of the measured displacement error and the displacement gradients are evaluated. As a result, it is found that the standard deviations of the displacement error and the displacement gradient are affected not only by the subset size and gage length but also by the measurement displacement gradient.