Research on the influence of trajectory and pitch angle on the deflection characteristics of projectiles into thin concrete targets

To investigate the coupled effects of trajectory angle and pitch angle on the deflection characteristics of projectiles penetrating thin concrete targets, an extensive numerical simulation study was systematically conducted, focusing primarily on the oblique penetration scenarios of single-layer concrete thin targets. The projectile was divided into six distinct segments (the nose section comprising 2 segments and the body section divided into 4 segments) for detailed force analysis to accurately capture its dynamic response. Various combinations of trajectory angles (ranging from 5° to 30°) and pitch angles (ranging from -6° to 6°) with different magnitudes and directions were selected to examine their individual and combined influences. The reliability of the numerical simulation method was rigorously verified based on the penetration test results of projectiles with different trajectory angles and pitch angles into two-layer spaced concrete targets. The results indicate that the deflection of the projectile is jointly caused by the reversal of the force direction on the projectile head and the change in the direction of the deflection moment induced by the forward motion of the projectile body during penetration. Under positive trajectory angle conditions, the trajectory exhibits an upward deflection. If a pitch angle is present, the sign of the pitch angle determines the direction of the trajectory deflection. When the trajectory angle and pitch angle are in the same direction, the attitude angle of the projectile after exiting the target first decreases and then increases in the opposite direction. Conversely, when the trajectory angle and pitch angle are in opposite directions, a smaller pitch angle causes the attitude angle of the projectile to continuously increase after exiting the target. In this scenario, a larger trajectory angle leads to the projectile undergoing three deflections during penetration. If the pitch angle exceeds 2°, the attitude angle of the projectile after exiting the target first decreases and then increases in the opposite direction.