Effects of steel fiber and target thickness on the penetration resistance of UHPC under high velocity small projectile impact loading

Abstract

Ultra high performance concrete (UHPC) with significant compressive strength and elastic modulus is expected to perform well under high–velocity impact loading. This paper introduces a study on the penetration resistance of UHPC based on variables including the thickness, fiber volume ratio, and striking velocity. The maximum striking velocity reaches approximately 1150 m/s. The results indicate that although the addition of steel fiber insignificantly improves the resistance, its effect on restraining the development of damage is non–negligible when the fiber volume ratio increases from 0.5% to 2%. The target thickness substantially influences the residual velocity and depth of penetration. Through computed tomography (CT) scanning, the damage can be divided into two parts: central damage (cratering, penetration tunnel, and scabbing) and interior cracks (radiate cracks, incomplete spalling cracks, and asymmetrical horn–shaped cracks). According to Forrestal's and the authors' previous models, satisfactory prediction results are obtained based on the suggested penetration resistance and modified cratering height.