Pore collapse during shock compression in granular materials: comparing in-situ experiments with analytical models*

A significant amount of the total energy used to shock compress powders is consumed in plasticity-induced pore collapse (Meyers 1999). In this work, X-ray phase contrast imaging (XPCI) of shock compression experiments was performed at the Dynamic Compression Sector (DCS) of the Advanced Photon Source (APS) with granular materials having varying ductility (aluminum, soda lime glass, Ottawa sand) and grain sizes (350 and 550 µm). From analyzing these XPCI images and employing an image generation algorithm and an optimization algorithm, the 3D particle-scale kinematics were inferred following the methodology of Gupta et al. (2021) with an improvement for modeling large deformation in ductile materials such as aluminum. The pore-size distribution during shock wave propagation was calculated and compared with analytical models of viscoplastic pore collapse developed by Carroll, Kim, and Nesterenko (1986), and the results were analyzed and interpreted for differences that arise as a function of grain material and size. This study will advance our understanding of the dynamic response of heterogeneous materials subjected to shock loading.