Microstructural imaging of simple shear deformation through synchrotron tomography

The micro-mechanical behaviour of granular materials controls their macro-mechanical response during shearing. This study aims to bridge the gap between both the micro and macro scales by introducing an imaging-friendly, modified simple shear apparatus. The modified simple shear apparatus combines an oedometer frame and components of a commercially available simple shear system to enable unrestricted imaging of grain samples under shearing. The modifications include the use of X-ray transmissive confining rings and manual shearing using a micrometre. Compliance testing against a conventional simple shear apparatus was conducted to verify the impact of these modifications. Using the modified apparatus, the fabric evolution of industrial-grade glass beads was successfully imaged and quantified before shearing, at peak and post-peak state by way of synchrotron X-ray microtomography. The evolution of scalar fabric parameters, including coordination number and porosity, was quantified across shear stages, demonstrating the effectiveness of the modified setup without compromising specimen size or boundary conditions.