Deformation Measurement of a SS304 Stainless Steel Sheet Using Digital Image Correlation Method

The digital image correlation (DIC) method is widely used in deformation measurements as it has the advantages of being a non-contact, high precision method that provides full field measurements, and requires simple experimental equipment. Traditionally, the grayscale speckle patterns captured by a monochromatic camera are used in the DIC method. With the growing development of consumer color cameras, there is great potential for developing color information in the DIC method. This paper proposes a displacement- and stress–strain-invariant DIC deformation measurement method based on the integer-pixel matching approach for speckle patterns during a tension test. For the integer-pixel matching stage, the load and displacement and stress–strain-invariant histories feature is used to estimate the initial value of the deformation parameters. In addition, this paper proposes a reverse retrieve strategy, instead of a forward search, to reduce the search time. Experiments show that the proposed DIC deformation measurement approach is not only capable of displacement invariance measurement, with robustness and high efficiency, but also that the average accuracy of the stress–strain result can reach 0.1%.