Strength of Ice VII: Hydrocode Modeling of Solidification Under Dynamic Loading Conditions

The solidification of liquid water to ice VII under quasi-isentropic loading has gained significant attention, with experimental and computational studies illuminating both homogeneous and heterogeneous nucleation processes and associated rates. However, the mechanical strength of ice VII post-solidification remains largely unexplored. To address this, a recent experimental campaign utilized pressure-shear plate impact experiments to induce shear waves in water at varying pressures, attempting to confirm the liquid-solid transition and measure the strength of ice VII. This effort performs computational simulations using CTH, a hydrocode from Sandia National Laboratories, to model the solidification process. Both phase transition (PTRAN) and SESAME equations of state (EOS) were explored, accepting these equilibrium models lack phase-transition kinetics. A tabular yield strength model (YLDTAB) was developed within CTH, which allows yield strength to be defined as a function of pressure, temperature, or density. Simulation benchmarking using previous uniaxial and pressure-shear data, culminated in the calculation ice VII strength through empirical approximations and CTH simulations, paving the way for advancements in understanding this unique phase transition. Future plans for YLDTAB include developing multi-dimensional yield strength tables, akin to SESAME tables. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. SAND2025-01573A.