Statistics of Impact Fragmentation of a Steel Sphere

Abstract

The dynamic fragmentation of a 2-mm steel spherical projectile at normal impact velocities ranging from 2.5 to 7.3 km/s impacting 1-mm bumper plates has been studied. The duralumin bumper and the porous bumper made from low-pressed fine copper powder with a density from 2.2 to 4 g/cc have been used. High-porous bumper is applied to decrease the effect of bumper fragments. The areas and the effective diameters for all craters have been measured in the witness plate. The threshold impact velocities for failure of the steel sphere at impact upon the duralumin and porous plates, and the number-size distributions for debris craters have been obtained. The main result of experiments is as follows: at decreasing of linear dimension of fine fragments of steel projectile, the density of number-size distribution is an increasing function. For statistical interpretation of data the Grady-Kipp and the Gilvarry exponential distributions were used. It is shown that the superposition of the above distributions allows to describe the statistical results on fragmentation of steel spherical projectile in the wide range of impact velocities.