A Novel Approach for Measuring the Discontinuous Deformation Fields Based on the Digital Image Correlation Method

An automatic discontinuous deformation measurement (DDM) approach was proposed to evaluate full-field deformations during the crack propagation process based on the digital image correlation (DIC) method. The color speckle pattern and crack identification procedure were applied at first in the DDM approach to obtain the region of interest (ROI) in the speckle images, the DIC analysis was then used to obtain the full-field displacements and strains of the cracked body. Three tests, the uniaxial tensile test (aluminum foil), the three-point bending and the four-point bending fracture tests (steel fiber reinforced cement-based composites), were conducted to validate the accuracy and reliability of the DDM approach. The experimental results demonstrated that the ROI images can be formed automatically, the evolution of the full-field displacements and strains were effectively obtained. Meanwhile, the DDM approach is applicable to the situations with single or multiple growing cracks. The crack mouth opening displacement values obtained by the DDM approach are agreed well with that obtained by the crack displacement clip gauge.