An experimental method for eliminating effect of rigid out-of-plane motion on 2D-DIC

• A general model is developed to predict the pseudostrain caused by out-of-plane motion in 2D-DIC.
• An experimental method based on laser strip method is used to measure the out-of-plane motion of specimen.
• Using the theoretical model and the information from the experimental method, the pseudostrain in 2D-DIC caused by out-of-plane can be corrected.

The out-of-plane motion is one of the most important factors that affect the precision of two-dimensional digital image correlation (2D-DIC). In this paper, a novel solution is presented to improve conventional 2D-DIC by eliminating the effect of out-of-plane motion, including translation and rotation. Firstly, an experimental technique using two projected laser strips is proposed to measure the out-of-plane motion of a planar specimen. A theoretical model is then established to predict the pseudostrains caused by out-of-plane motion based on the pin-hole imaging model. Using the measured out-of-plane displacement, the captured deformed images used in 2D-DIC are amended to eliminate the effect of out-of-plane motion by the theoretical model. Finally, two experiments were conducted to validate the effectiveness of the proposed method. Results indicate that application of the proposed method can effectively eliminate the errors caused by out-of-plane motion.