Increasing Measuring Area of Deformed Solid by Digital Image Correlation

Knowledge of mechanisms of deformation and fracture of constructional materials allows optimizing their composition and microstructure. The digital image correlation technique is used for this purpose due to its high accuracy and simplicity in data processing. Physical processes at the meso-level are studied by optical microscopy, which, however, reduces the measuring area. The paper presents a short description of approaches allowing to increase the measuring area without loss in accuracy. It is shown that this problem can be solved by stitching the overlapping fields of view or separate displacement fields to obtain a combined displacement field. Another solution of the problem is associated with a decrease in the optical magnification, while the invariance of the absolute error at the given level is provided by the calculation of sub-pixel accuracy. In this paper, this approach is applied to the welding joint under fatigue loading conditions.