Fragmentation of a steel sphere by a high-velocity impact on a highly porous thin bumper

The number-size distribution of fragments arising during fragmentation of a steel projectile upon its normal impact on a thin bumper with a velocity of 2.5–7.3 km/sec is obtained. High-porous sheets made of fine copper powder are used to reduce the number of large fragments of the bumper in the debris cloud behind the bumper. As the impact pressure increases from 30 to 160 GPa, the character of fragmentation of the steel sphere changes from irregular fragmentation near the projectile-failure threshold to more uniform fragmentation with the maximum impact velocity. The main result of the experiment is the observation that the density distribution of the number of fragments increases and does not tend to zero as the size of fragments decreases. The data are analyzed within the framework of the Grady and Gilvarry exponential distributions.