INFLUENCE OF SCALE ON THE PENETRATION OF TUNGSTEN RODS INTO STEEL-BACKED ALUMINA TARGETS

As ballistic tests are often performed in reduced geometrical scale, t he scaling laws are important for the interpretation of the results. I n this study, we tested the validity of replica scaling, by which we m ean that all geometrical dimensions are scaled uniformly, while the ma terials and the impact velocity are kept the same, Long tungsten proje ctiles with length-to-diameter ratio 15 were fired against unconfined alumina targets with steel backing. The tests were carried out with im pact velocities 1500 m s(-1) and 2500 m s(-1), and in three different scales with projectile lengths 30, 75 and 150 mm (diameters 2, 5 and 1 0 mm). The alumina targets were photographed by means of a high-speed camera, and the tungsten projectiles were photographed inside the alum ina targets by means of flash radiography. Also, the residual penetrat ions in the steel backings were measured. The Johnson-Holmquist model for ceramic materials was implemented into the AUTODYN code, which was used for simulation of the experiments. The agreement between results of experiment and simulation was fair, and over the tested interval o f scales replica scaling was found to be valid with reasonable accurac y.