The Incipient Failure of Glass Beads and Glass Bead/Epoxy Composites Under Compression as Observed by In Situ X-Ray Micro-Computed Tomography

Granular materials are utilized in various applications, including civil engineering, energy, and defense. They exhibit very different mechanical behavior under different loading conditions. Glass beads are often used as a model granular material in simulations due to their regular geometries. In this study, we focus on understanding the incipient failure of confined glass beads assembly and a glass bead/epoxy composite under quasi-static compression using in situ X-ray micro-computed tomography (μCT). An μCT system with an integrated mechanical loading frame provides in situ volumetric images in quasi-static compression. Glass beads of various diameters (2, 3, 4, and 5 mm) are placed inside a hollow cylinder, creating an assembly consisting of glass beads with different combinations of volume fraction and particle contacts. In addition, glass bead/epoxy composite cylindrical specimens are also prepared and compressed in a separate set of experiments. The deformed configurations of such glass bead assembly and the glass bead/epoxy composite specimens at different strain levels are captured by the μCT volumetric images. The incipient failure and the damage behavior of glass beads, under the rigid confinement as well as within the epoxy binder in quasi-static compression, are visualized and assessed. This work provides experimental results for the validation of mesoscale simulations.