Effect of bio-inspired surface pattern (Pangolin's scales) and grooved mechanisms on the high velocity ballistic performance of aluminum 6061-T6 targets.

The individual influence of target dynamics, curvature, bio-inspired (Pangolin's scale) surface pattern, and presence of external ('V'-shaped) and spaced internal grooves ('M'-shaped) on ballistic performance of lightweight aluminum (6061-T6) target has been investigated. Target thickness of 10 mm and an armor piercing projectile of 9 mm diameter, 7.85 g weight were considered for the numerical simulation. The initial impact velocity of the projectile was varied in the range of 400 to 800 m/s. Compared to the static target, the exit velocity of the projectile was observed to be less (2.3%) for the dynamic target. When the target is moving, it significantly alters the penetration direction and increases the travel length of the projectile. When the 'α' of the target was increased (5 mm to 8 mm), significant improvement (3.63%) in ballistic performance was noted. Among the several conditions simulated, when the curved target received the projectile's impact at an offset distance (35 mm) from the center of the target showed a better performance (up to 10.7%). In addition an angular deflection (–5.1°) of the projectile from the center of the target was noted. Compared to curved targets, increased angular deflection (35°) of the projectile was observed for target having bio-inspired (pangolin's scale) pattern. This is due to cantilever action offered by the scaled pattern. Even though the presence of V-notch pattern could able to resist the projectile's impact, the ballistic resistance was observed to be marginal due to higher stress concentration at the notch root region. Compared to all other cases, the spaced internal grooves ('M' shape) inside the target, enhanced the ballistic resistance (72%) for groove dimensions of pitch and width of 3.5 mm and 0.5 mm. [ABSTRACT FROM AUTHOR]