Digital image correlation using energy minimization in full-field displacement and strain measurement

Abstract

Digital image correlation (DIC) method is an effective way for full-field strain measurement. Optical flow estimation methods combined with a global searching strategy for displacement field measurement are introduced in this paper. Compared with the conventional DIC method, this strategy can lessen possible mismatching between the reference image and warped image. By minimization the energy function of displacement field, displacement continuity and displacement gradients continuity among calculation points are achieved. For detecting large displacements, a coarse-tofine strategy is also employed. More importantly, the architecture parallelization of optical flow estimation and searching strategy can decrease the running time of this method for time-critical conditions. This proposed method is universally applicable to the images with shadows, rotation, and large deformation. Several pairs of simulated digital speckle images were used to evaluate the performance of this novel DIC method, and the experimental results clearly demonstrate its robustness and effectiveness.