Quantifying 3D Particle and Pore Dynamics During Rapid Compaction of Rapid Granular Materials

We describe a new technique for inferring 3D particle and pore dynamics during rapid compaction of granular materials and its application to studying soda lime glass and aluminum powders impacted at velocities ranging from 0.7 km/s to 2.1 km/s. The technique for inferring 3D particle and pore dynamics involves performing an initial 3D characterization of the granular packing using x-ray computed tomography and then applying an optimization algorithm that updates the displacements and strains of individual particles by comparing synthetic x-ray phase contrast images with in-situ images. Impact experiments and imaging were performed at the Dynamic Compression Sector (DCS) of the Advanced Photon Source (APS) using a powder gun and four PI-MAX cameras. The scientific objective of the experiments was to identify the distribution of porosity in the granular medium as velocities increase from the quasi-static regime, in which particles only partially plastically deform, to the dynamic regime, in which particles significantly deform, flow, and melt. We describe prior work in which the method was validated using finite element simulations and future work investigating the role of particle material and morphology on pore collapse across the quasi-static to dynamic transition.