Strain measurement errors with digital image correlation due to the Savitzky-Golay filter-based method

摘要

Recently, an effective yet easy-to-use strain measurement method, which is based on the Savitzky-Golay filter, was proposed for full-field strain measurement using the digital image correlation technique (DIC). The Savitzky-Golay filter-based method is derived based on a given polynomial. When the order of the deformation is not the same as that of the employed polynomial, the mismatched problem may lead to strain measurement errors. However, in real experiments, the order of the deformation is unknown. In general, the order of the real deformation is higher than that of the employed Savitzky-Golay filter-based method. So, in this paper, strain measurement errors due to the matched or undermatched Savitzky-Golay filter-based method are carefully examined using simulated and real experimental patterns. Four different orders of strain deformations are employed to investigate the matched or undermatched problems. The influence of the strain window size and grid space on the strain measurement are also studied in the paper.