Ballistic behavior of bioinspired layered-and-staggered concrete

Abstract

Inspired by the structure of abalone shells, a layered-and-staggered concrete system composed of concrete tiles joined with rubber mortar was proposed for ballistic protection. Ballistic tests demonstrated that, when subjected to Type 53 API bullet impact at velocities ranging from 780 to 815 m/s, the layered-and-staggered concrete outperformed both steel fiber reinforced bulk concrete and simple layered concrete with comparable compressive strengths in terms of reducing bullet penetration depth. Furthermore, damage in the layered-and-staggered concrete was primarily confined to areas surrounding directly impacted tiles or joints; cracks on the impact face did not propagate radially as observed in bulk concrete but instead deflected along weak interfaces between adjacent tiles. Additionally, crack deflection and bullet yawing were observed in the thickness direction of the layered-and-staggered concrete targets, aligning with expectations for bionic design effects. Incorporating steel micro-fibers into the layered-and-staggered system enhanced individual tile's impact resistance but did not reduce bullet penetration depth. The proposed layered-and-staggered concrete exhibits promising potential for practical applications, particularly in scenarios requiring prompt repair of damaged components.