Rotary shear experiments under X-ray micro-computed tomography.

A rotary shear apparatus (ERDμ-T) was designed, assembled, and calibrated to study frictional behavior. We paired the apparatus with X-ray micro-computed tomography (μCT) to inspect in situ and in operando deformation of the tested specimen. This technology allows us to observe how two rough surfaces interact and deform without perturbing the experimental conditions (e.g., pressure, temperature, and sample position). We performed an experiment employing an aluminum alloy sample to demonstrate the capability of the apparatus. The sample was sheared at incremental steps, and during shearing, normal force, sample shortening, torque, and shearing velocity were measured. The measurements were associated to the μCT imagery, giving a comprehensive understanding of the deformation processes of the samples. The present contribution demonstrates that the ERDμ-T allows (1) linking the variation of physical parameters to the evolution of internal structures of the sample and (2) shedding light on fracturing and frictional sliding processes in solid materials.