Improvement of high-temperature deformation measurement accuracy based on image restoration method

Digital image correlation (DIC) is a full-field and non-contact technique based on white-light illumination for displacement and strain measurement. Because of these advantages, it can be used to measure the mechanical properties of materials at high temperature. However, there are still many urgent matters to be solved in using the DIC method in high-temperature measurement, such as the heat flow disturbance. This can warp the images acquired in high temperatures and cause a tiny move of the images acquired at the same temperature, even making the gray value of the images change, so the results of the measurement will not be guaranteed. This paper proposes a method to reduce these influences and improve the accuracy of high-temperature measurement results. Degraded images can be processed by using a combination of the image inverse filter method and an image averaging algorithm. Then the processed images can be used to calculate the displacement and strain. The experimental results show that using an image inverse filter and image averaging algorithm to process images can produce smaller RMS errors and more stable results than the values calculated from the original images with no processing. Using this method can improve the accuracy of high-temperature measurement.