Impact Experiments Into Borosilicate Glass at Three Scale Sizes

Abstract

Glass impact experiments were designed at three different scales—0.22-cal, 0.375-cal, and 0.50-cal—named after the diameter of the bullets. Four experimental series were conducted at the three scale sizes: (1) Lexan®-only experiments; (2) monoblock glass experiments; (3) single impact bonded glass experiments, and (4) multi-hit experiments. The experiments were conducted to obtain residual velocity Vr as a function of impact (striking) velocity Vs, including sufficient partial penetrations to calculate a ballistic limit velocity V50. The Vs – Vr data were fit to the Lambert equation to obtain another estimate of V50. The objective of the experiments was to investigate whether a time dependency exists in glass damage/failure for ballistic experiments, and if so, quantify this dependence. No scale effect was observed in experimental results for the Lexan®-only experiments. But a variety of scale effects were observed in the glass impact experiments, suggesting that failure is time dependent within the timeframe of ballistic events.