Experimental observations and computer simulations of spherical aluminum-alloy projectiles impacting plane limestone targets
The stress distribution within spherical aluminum-alloy (2024) projectiles impacting plane limestone (calcite) targets was observed by converting residual microhardness maps obtained for cross-sections of recovered projectiles impacting from 0.8 to 1.3 km/s. A maximum residual yield stress zone was observed to migrate toward the rear of the impacting projectiles with increasing impact velocity. The maximum occurred at a normalized depth z′/am ≅ 0.5 (where am is the contact radius); consistent with the theoretical result for elastic impacts. Computer simulations showed good agreement with experiment, and demonstrated that elastic assumptions were valid well into the plastic deformation regime.