Study of elastoplastic deformation and crack evolution mechanism of single-crystal ice during uniaxial compression using 3D digital image correlation

Single-crystal freshwater ice was subjected to uniaxial compression tests with different strain rates and crystal orientations, and the real-time full-field deformation and strain were measured by the three-dimensional digital image correlation (3D DIC) method. The mechanism of elastoplastic deformation and crack evolution of single-crystal ice is discussed based on the basal slip. The maximum compressive strength appeared when the crystal orientation (angle between the C-axis and loading direction) θ=0°/90°. When 45°<θ<90°, an inclined bearing layer appeared and caused the specimen to rotate simultaneously. When 0°<θ⩽45°, the vertical compressive stress was sequentially transmitted through the basal plane, two diagonal expansions to the sidewall appeared. The failure mode and compressive strength of ice exhibited a ductile–brittle transition. The strength was positively correlated with the strain rate below the ductile–brittle transition range. The stress concentration at the crack tip was released through basal slip, inhibiting crack propagation, which showed multi-crack ductile failure. When in the ductile–brittle transition range, the cracks could grow stably, leading to axial splitting failure. When the strain rate was higher, the crack tip could not grow stably, producing inclined cracks and resulting in spalling or axial splitting failure, and the ice exhibited a brittle failure mode.