Nonlinear elastic response of shocked fused silica

Large amplitude, combined compression and shear wave measurements have been obtained in fused silica (Dynasil 1000) shocked to a peak compressive stress of 6 GPa. The in‐material, particle velocity profiles are analyzed to obtain the longitudinal stress‐density relation for uniaxial strain and shear wave velocities in the shocked state. The shear wave velocity decreases with compression to a density compression of 7.6%, and then increases with compression. Bulk modulus, Poisson's ratio, and mean stress in the shocked state were determined from the experimental data. Comparison of the shock and hydrostatic compression results show that the fused silica displays reversible, shear‐enhanced compaction. Although two of the three third‐order elastic constants (C111 and C166) can be calculated from the present data, the difficulty in describing the fused silica response in terms of third‐order constants is discussed. A microscopic model to explain shear enhanced compaction is suggested. [Work supported by AFOSR,...