Scaling laws for size distribution of fragments resulting from hypervelocity impacts of aluminum alloy spherical projectiles on thick aluminum alloy targets: Effects of impact velocity and projectile diameter

The effects of projectile diameter and impact velocity on fragment size distribution were investigated by striking aluminum alloy 6061-T6 targets with aluminum alloy 2017-T4 spheres of 1.6 to 7.0 mm in diatheter at impact velocities ranging from 2 to 7 km/s. Two-stage light-gas guns from the Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency and Nagoya Institute of Technology were used for the experiments. After the impact experiments, fragments were collected from the test chamber, and the fragment lengths were measured. Scaling laws for size distribution of fragments were discussed. The fragment length was directly proportional to projectile diameter. When the horizontal axis of the fragment length distribution was divided by the projectile diameter, the normalized fragment length distribution was proportional to the impact velocity raised to the power 1.5. The empirical formula with respect to the fragment length distribution could be expressed using the projectile diameter and impact velocity. The proposed scaling law with respect to fragment length could be applied to projected areas of fragments and fragment masses and the validity of the scaling law was confirmed. The fragment length was directly proportional to crater size such as crater diameter and crater depth. The horizontal axis of the fragment length distribution could be normalized by each crater depth or crater diameter. (C) 2017 Elsevier Ltd. All rights reserved.