Equation of State and Evidence of Enhanced Phase Transformation for the Shock Compression of Distended Compounds

Shear stress and deformation is inherent to shock-wave compression. Shear deformation is enhanced when the material subject to shock compression is in an initial distended state. Shock Hugoniot data for full-density and porous compounds of boron carbide, silicon dioxide, tantalum oxide, uranium dioxide and playa alluvium are investigated for purposes of equation-of-state representation of intense shock compression. Hugoniot data of distended materials reveal evidence of accelerated solid-solid phase transition as a consequence of shock compaction and accompanying enhance shear deformation. A phenomenological thermo-elastic equation-of-state model is constructed that accounts for both deformation- induced phase transformation and the extreme shock compaction of distended solids, and applied to the compounds studied.