Double-layer high-porous copper/duralumin bumper

Normal impacts of a spherical steel projectile 2-mm in diameter on double-layer bumpers are investigated experimentally in a velocity range from 2 to 7.3 km/s. One layer of the bumpers is made of fine copper powder, and the other is made of duralumin. The high-porosity copper/duralumin double-layer bumper of the same thickness and areal density performed better than a single-layer duralumin bumper for impact velocities ranging from 3 to 5 km/s. The maximum depth of penetration of projectile fragments decreased and a smaller number of large craters were observed in the witness plates for the tests with the double-layer bumpers. The order of the layers in the bumper did not have a significant effect on the projectile's failure. As the impact velocity increased to 7 km/s, the difference between the protective properties of the single-layer and double-layer bumpers disappeared. (C) 2003 Published by Elsevier Ltd.