Experimental investigation on the cellular steel-tube-confined concrete targets against projectile impact

Abstract

Steel-tube-confined concrete (STCC) targets show better anti-penetration performance than semi-infinite concrete targets as the steel tube imposes constraint on the in-filled concrete to enhance its strength and toughness. Cellular structural system for in-plane and multi-layer overlay extension is an effective way to promote the application of STCC targets to practical protective structures. In this paper, penetration tests of cellular STCC targets (single-layer and double-layer 7-cell hexagonal STCC targets) impacted by 12.7 mm Armor Piercing Projectile (APP) were conducted, and side length and thickness of steel tube, steel ratio, impact point and velocity, and repeated impacts were considered. Moreover, single-cell STCC targets and semi-infinite concrete targets were also designed and tested for comparison with the cellular STCC targets. The typical damage modes and parameters of the tested cellular STCC targets including the range, depth and volume of funneled crater and depth of penetration (DOP), were obtained and discussed. It is shown that the 7-cell hexagonal STCC targets show improved anti-penetration performance in comparison to the single-cell STCC targets under the same conditions; the anti-penetration performance of the double-layer 7-cell hexagonal STCC targets was weakened due to the free surfaces between the layers; the side length and thickness of steel tube, steel ratio and impact velocity have significant influence on the DOP of the 7-cell hexagonal STCC targets; optimizing the side length and thickness of steel tube could greatly improve the anti-penetration performance of the cellular STCC protective structures. Moreover, the 7-cell hexagonal STCC targets also show excellent anti-penetration performance under the repeated impacts of 12.7 mm APP.