Experimental Verification and Numerical Simulation ofSteel Needles Impacting on Glass

In order to verify the probability of hand-thrown needles penetrating a glass plate, the damage features and the ballistic limit velocity were studied using both one-stage gas gun experiments and AUTODYN simulations on the glass plate impacted by common steel needles at velocities of tens of meters per second.Our results show that the damage of the glass plate concentrates in a small region around the impact point, and a cone-shaped hole is formed on the back side of the glass plate.The ballistic limit velocities are determined by the mass and the nose shape of the needles, the thickness of the glass plate, and the impact angle.Furthermore, when the velocity of the needle reaches 30 m/s and the impact angle is less than 10°, the steel needle with a mass of 0.35 g may penetrate a 1.6 mm thick glass plate.Compared with ogive-nosed steel needles, flat-nosed needles penetrate the glass plate more easily, and the damage of the glass primarily results from shear and tensile stresses.The ballistic limit velocity increases with the increases of the glass thickness and the impact angle and decreases with the increase of the needle mass.