Dynamic yield strengths of B4C, BeO, and Al2O3 ceramics

The dynamic yield strengths for several ceramics were measured under shock-wave compression. The Hugoniot elastic limit (HEL), taken as the amplitude of the observed elastic precursor traveling ahead of the compressional wave, was 154 and 82 kbar for B4C and BeO ceramics, respectively, and ranged from 61 to 134 kbar for several Al2O3 ceramics. These values apply to 6-mm-thick samples; in some cases there were variations with sample thickness. The offset of the Hugoniot from the isotropic compression curve in the stress-volume plane indicates a nonzero yield strength above the HEL for Al2O3. This yield strength is somewhat less than the yield strength at the HEL. The compaction of porous ceramics is found to follow a quadratic variation with stress, full compaction being reached at about four times the HEL.