Inferring 3D Behavior of Dynamically Compressed Granular Materials from X-ray Tomography and Dynamic Radiography Measurements*

Dynamically compressed granular materials have primarily been studied using macroscopic measurements (e.g., VISAR, PDV). However, simulations and x-ray imaging measurements have revealed the rich, heterogeneous behavior occurring at the microscale during dynamic compression of granular materials: force chains, non-planar shock fronts, porosity-dependent shock velocities.

I will present the results of recent shock compression experiments performed on granular materials composed of spherical and angular particles at the Dynamic Compression Sector (DCS) of the Advanced Photon Source (APS). We integrate: (1) sample characterization with x-ray computed tomography (XRCT), (2) dynamic x-ray phase contrast imaging (XPCI) performed in situ, (3) an x-ray phase contrast or absorption image generation algorithm, and (4) an optimization algorithm to combining XRCT and XPCI to infer the time-evolution 3D particle positions. We are using this approach to understand the energy budget local heterogeneity, shock-front planarity, and porosity and inter-particle contact-network dependence of shock events.