Stress Distribution and Deformation Behavior of Alumina Ceramic after Mini Bullet Dynamic Impact

Alumina ceramics sintered at 1350, 1450 and 1550 °C with different grain sizes were tested under dynamic load using a small-scale compressed air gun with sharpened tungsten carbide bullets impacting at a sub-ballistic velocity of 360 km/h. The deformation behavior and sub-surface cracks were recorded by visual examination. Cr³⁺ fluorescence was used to measure the residual stress distribution on and beneath the impact site. The results show the alumina sintered at 1350 °C with a fine grain size of 1.7 μm and high hardness of 18.3 GPa is good at bulletproof due to the cone cracks can spread the dynamic stress effectively and consume much impact energy.