Automated Calibrated Modeling Method of Multiphase Equations of States: Applied to Tin

Equations of state (EOS), combined with the partial differential equations of describing conservations of energy, momentum and mass, form a complete set of fluid dynamics equations on solving dynamic compression behaviors of material. Under dynamic compression, phase transition of material may lead to discontinuous changes of its internal energy, density, strength and other properties, and a multiphase EOS is needed to accurately describe these changes. An automated modeling code of multiphase equations of state (AEOS) is developed, which can construct multiphase EOS model in an automatic way and calibrate parameters of EOS models with a computer intelligent optimization algorithm. By applying AEOS to tin, we obtain three sets of multiphase EOSs. The theoretical results of all the three sets of EOSs are consistent well with the experimental results, which validates the good performance of the AEOS code. And we find that the isentropic release path of tin passes through the three-phase point of the β, the body centered tetragonal (bct), and the liquid phases, when tin is impacted to 17 GPa and then isentropically released to atmospheric pressure. In addition, this result can well explain the experimental phenomenon that tin ejection particles are in a solid-liquid mixture state under the very low impact pressure of 15.4 GPa. The good performance of AEOS insures that it can be widely applied to integrated digital scientific research platforms and scenarios of high-flux material property calculations in the near future.