Damage evolution study of sandstone by cyclic uniaxial test and digital image correlation

The damage evolution process and crack development of rocks under cyclic uniaxial compression were studied. In this work, sandstone samples subjected to axially cyclic loading with different amplitudes were tested and optical images of specimen surface in loading-unloading periods are presented for digital image correlation (DIC) analysis. The experimental results obtained are then used to determine apparent strains of the sandstones by means of DIC approach. The apparent strains are in turn employed to describe the process of damage evolution, crack nucleation and propagation until failure. Axial load-displacement curves show that the residual displacement increases slightly with an increase in cycles and the dissipated energy decreases rapidly after the first cycle then tends to remain constant. It is found from the full-field apparent strains that when the amplitude of the cyclic load exceeds a certain value, the value of cycles has a significant effect on the apparent strain localization and damage evolution. (C) 2013 Elsevier B.V. All rights reserved.