Three-dimensional mesoscopic investigation on equation of state for dry sand under shock compression

Abstract

The dynamic behavior of dry sand subjected to intensively dynamic loads such as blasts and projectile penetration is a topic of current research for military protection engineering. The equation of state (EoS) plays a crucial rule under such high pressure and high strain-rate. However, experimental investigation on the EoS of dry sand with a comprehensive considerations of sand configuration, such as the particle shape, grain composition and porosity is a complex and expensive task. In the present study, a well-established three-dimensional mesoscopic model for dry sand is presented, in which the dynamic behavior of sand particle (quartz) are described by the HJC model with systematically calibrated parameters. The mesoscopic model is then used to investigate the dynamic response and EoS for dry sand subjected to shock compression and is validated against existing fly-plate-impact test data, in which two homogenization methods used to connect the mesoscopic variables and macroscopic EoS are adopted. A thorough analysis of the numerical shock compression simulation demonstrates that the shock compression of dry sand system can be divided into three stages, i.e., the initial rearrangement of particles, the following formation of stable force chains and the final translation motion. Finally, the effect of sand configuration on the EoS is systematically conducted. It is found that the particle shape and grain composition have limited influence on EoS, the friction between sand particles moderately influences the EoS and porosity strongly influences the EoS.