Analytical and Mesoscale Models for Shock Compression of Particle Mixtures with Linear and Nonlinear Hugoniot*

We use theory and computation to explore the relationships between particle size and timescale in reaching various thermodynamic states following shock compression of particle composites without porosity in the weak shock limit. First, mesoscale simulations are used to evaluate thermal equilibration timescales for composites containing spherical particles of different sizes at representative shock-state temperatures. The results are used to define regimes of mechanical and thermal equilibrium and to corroborate model assumptions. Corresponding Hugoniot mixture models are then compared to mesoscale hydrodynamic simulations of shock-compressed composites with Hugoniot relationships that are linear (aluminum/copper mixtures) or nonlinear (ceria/polyethylene mixtures) to explore the utility of various homogenization approaches.