Improvement on measurement accuracy of high-temperature DIC by grayscale-average technique

•A method to minimize the thermal disturbance in high-temperature DIC is proposed.•A method to characterize the intensity of the thermal disturbance is developed.•Effect of image number and temperature in grayscale-average technique is studied.

In this paper, an effective grayscale-average technique is proposed to minimize the thermal disturbance in digital image correlation (DIC) measurement method under high-temperature atmosphere environment. First, both the grayscale-average technique and the simulated high-temperature speckle image are developed to investigate the influences of thermal disturbance on DIC method under high-temperature environment. Second, a high-temperature DIC experiment has been performed to verify the validity of the proposed grayscale-average technique. Finally, the displacement fields and average thermal strains of several temperature conditions are extracted from the simulated speckle images and the experimental images, also the effects of the image number and the temperature in the grayscale-average technique are analyzed. The results will provide a new method for improving the measurement accuracy in DIC full-field deformation measurement under high-temperature atmosphere environment.