Polyurea coated composite aluminium plates subjected to high velocity projectile impact

High velocity projectile penetration through polyurea coated AA5083-H116 aluminium alloy plates has been studied. The effect of different polyurea thickness on the residual velocity of full metal jacket (FMJ) projectiles is examined and presented. Steel-tipped 5.56 calibre (5.56 × 45 mm) projectiles were fired at coated aluminium plates from a distance of 10.0 m at a fixed velocity of 945 m/s. Seven configurations of plate arrangements with different total thicknesses were used. Each configuration consisted of combinations of 5 mm and 8 mm base plates (AA5083-H116) with 6 mm and 12 mm polyurea layers. A 5.56 calibre gun was used to shoot at close range, where the targets were placed perpendicular to the flying direction of the projectile. The input and output velocities were measured using two laser velocity screens. The effectiveness of the polyurea coating in terms of reduction of the residual velocity, damage mechanism, kinetic energy absorption of the plates, and the effect of different layer configurations on residual velocity are presented and discussed. By comparing the different thicknesses of polyurea coatings, it indicated a good ability in absorbing energy, and subsequently, in a reduction of the residual velocity of the projectiles. Also, the ability of the polyurea coating to act as a protective shield against flying particles and fragments was established.