Displacement measurement of specimen surfaces with damaged areas by digital image correlation

• We investigate the effects of damaged areas in specimen surfaces to digital image correlation.
• Coefficients are set to each pixel for the correlation criterion according to the qualities of them.
• The displacement calculation accuracy of the pixels near damaged areas is improved.

A novel 2D digital image correlation technique is developed to calculate displacement of specimen surfaces with damaged areas. The effects of damaged areas in specimen surfaces to digital image correlation are investigated in this paper. In order to improve calculation accuracy and use all pixels sufficiently in subsets, coefficients are set to each pixel according to the qualities of them. With the calculation path which is from pixels with higher correlation to lower ones, the displacement calculation accuracy of the pixels near damaged areas is improved by the proposed method. The efficiency of the proposed method is tested by computer simulated images with random speckle. Compared with traditional DIC techniques which treat all pixels equally in a subset, the proposed technique is more suitable to specimen surfaces with damaged areas.