Effect of Specimen Size on Localization using Digital Image Correlation

Failure of structures made of brittle materials like rock and concrete exhibits deterministic size effect on post-localization mechanical behavior. The application of advanced image-based instrumentation, along with conventional testing can provide full-field strain and its evolution that can be useful for the analysis of localized behavior of brittle materials. In this view, this study collaborates the Digital Image Correlation technique (DIC) with lateral strain-controlled uniaxial compression tests on Hawkesbury sandstone for insights into size effect on localized behavior. Full-field strain obtained from DIC is synchronized with macroscopic responses to investigate the effect of specimen size on strain localization mechanism. Results from this study demonstrate that the increase in specimen size intensifies the local scale deformation, accelerates the localization process, and increases both strain gradients across the shear band and shear band thickness. The shear band evolution analysis in this study also provides rich quantitative data useful for the development of constitutive models to capture size effect on the behavior of rocks.