Damage Mechanisms of Chemically Strengthened Glass Bars Due to High-Velocity Ball Impact

Abstract

Ball impact experiments were conducted on unstrengthened and strengthened glass bars at 261 and 345m/s, respectively. Damage propagation was recorded using a high-speed camera at frame rates of 281,000 frames per second. Immediately after the ball impact on the unstrengthened glass, the damage front reached a maximum velocity of 1,967m/s before falling to zero within a short distance. However, the longitudinal wave created due to the impact continued down the bar towards the rear-end. Upon reflection from the rear-end of the bar, a secondary damage front was initiated at 3,192m/s, which eventually arrested. On the other hand, the damage front in the strengthened glass reached a maximum of 2,275m/s immediately after impact, and then stabilized at 1,921m/s until the bar was consumed. It was determined that the stored elastic energy in the strengthened glass fueled the self-sustained damage and allowed it to propagate at a near constant rate. For both glasses, high-speed imaging allowed for observation of energy dissipation modes such as fracture propagation (fracture surface area), radial bar dilation, and high velocity jetting of fine glass particles at the impact site. In addition to the triangular dilation observed in the unstrengthened glass at the impact site, the strengthening process also led to uniform dilation of the entire rod.