The effect of concrete target diameter on projectile deceleration and penetration depth

We conducted sets of experiments with three diameters of concrete targets that had an average compressive strength of 23 MPa (3.3 ksi) and 76.2-mm-diameter, 3.0 caliber-radius-head, 13-kg projectiles. The three target diameters were D=1.83D=1.83, 1.37, and 0.91, so the ratios of the target diameters to the projectile diameter were D/d=24D/d=24, 18, and 12. The ogive-nose projectiles were machined from 4340 Rc45 steel and designed to contain a single-channel acceleration data recorder. Thus, we recorded acceleration during launch and deceleration during penetration. An 83-mm-diameter powder gun launched the 13-kg projectiles to striking velocities between 160 and 340 m/s. Measured penetration depths and deceleration-time data were analyzed with a previously published model. We measured negligible changes in penetration depth and only small decreases in deceleration magnitude as the targets’ diameters were reduced.