The digital image correlation method is useful and widely used to measure the deformation of thin film materials for mechanical testing and provides full-field deformation of the specimen. The accuracy and precision of the digital image correlation method depends on the quality of the image obtained during the test. The noise included in the digital image causes errors in the calculated displacement results. Strain is calculated by differentiating the displacement, so the effect of noise is amplified in the calculated result of strain. Therefore, noise is one of the most important factors in measuring displacement using images. In order to evaluate the effect of noise, one hundred images were taken continuously in a stationary state and the distribution of the local strain was calculated using digital image correlation. If the size of the subset is greater than 15×15pixel, the calculated results for strain show that the effect of noise is within the maximum error range of 1% and the standard deviation is 0.11% or less.

This research presents a uniaxial static stress estimation method for concrete structures by using digital image correlation (DIC) and finite element method. DIC is employed to measure the displacement field, which is induced by drilling a small hole on the concrete surface. The initial static stress level can be estimated by comparing the measured displacement field to that from the corresponding finite element model. A series of experiments in the laboratory environment is conducted to validate the proposed method.