X-ray tomography system to investigate granular materials during mechanical loading

TL;DR

This paper presents a portable X-ray tomography system integrated with mechanical testing to enable in-situ 3D imaging of granular materials under load, providing detailed insights into packing structures with moderate noise levels.

Contribution

The authors develop a novel, portable X-ray tomography setup using a medical C-arm for in-situ imaging during mechanical loading of granular materials, including system design, calibration, and image reconstruction methods.

Findings

Achieved 0.52 mm resolution in 3D reconstructions

Successfully imaged granular packings under load

System exhibits moderate noise levels in reconstructions

Abstract

We integrate a small and portable medical x-ray device with mechanical testing equipment to enable in-situ, non-invasive measurements of a granular material's response to mechanical loading. We employ an orthopedic C-arm as the x-ray source and detector to image samples mounted in the materials tester. We discuss the design of a custom rotation stage, which allows for sample rotation and tomographic reconstruction under applied compressive stress. We then discuss the calibration of the system for 3d computed tomography, as well as the subsequent image reconstruction process. Using this system to reconstruct packings of 3d-printed particles, we resolve packing features with 0.52 mm resolution in a (60 mm)$^3$ field of view. By analyzing the performance bounds of the system, we demonstrate that the reconstructions exhibit only moderate noise.