Edge-on impact investigation of fracture propagation in boron carbide

The fracture propagation in boron carbide was visualized in a high-speed photographic study. The specimens of the dimensions 100 mm x 100 mm x10 mm were tested in the so called Edge-On Impact (EOI) configuration and damage propagation was observed by means of a Cranz-Schardin camera, which allows for a maximum frame rate of 10 MHz. Steel cylinders of 30 mm diameter and 23 mm length were used as projectiles. Fracture patterns, single crack velocities and fracture front velocities (damage velocities) were determined as a function of impact velocity, which was varied in the range from 50 m/s to 1000 m/s. Damage velocity increased as the impact velocity was increased. The damage velocity varied in the range from 5796 m/s at an impact velocity of 50 m/s up to 12406 m/s at an impact velocity of 1010 m/s. The damage velocity versus impact velocity curve exhibited a plateau for impact velocities in the range from 100 m/s to 700 m/s, where the damage velocity was about 9000 m/s.