Impact mechanisms of aggregate on rigid projectile normal penetration into concrete target

Abstract

<p indent=0mm>Concrete failure mechanisms under projectile penetration at a mesoscale level have recently attracted researchers’ attention. Based on the three-dimensional (3D) mesoscale concrete model, the influences of aggregate strength, size, and volume fraction on deflection angle and penetration resistance of projectile were analyzed during the process of rigid projectile penetration into the concrete. Four stages of projectile deflected during the process of depth penetration were described. The measurement of the deflection angle of the projectile during the penetration process revealed the factors affecting ballistic stability. These factors were investigated quantitatively, and their critical values affecting the deflection angle of projectile were obtained. The effects of the key variables of coarse aggregate on penetration resistance were quantitatively studied. Then, the applicable conditions to satisfy the homogeneous assumption and the upper bounds of aggregate size and volume fraction were identified. The latter influenced the penetration resistance and were dependent on the aggregate configurations. Finally, the influencing mechanisms of coarse aggregate on the rigid projectile normal penetration into mesoscale concrete were described. The results reported here provide a theoretical and practical background for design optimization and safety assessment for protective engineering structures.