Damage Behaviors of a Ceramic Plate due to Collision of a Flying Sphere

The impact damage in a silicon carbide plate caused by a collision of a silicon nitride sphere was characterized through microscopic observations as well as an analysis based on the Hertz's contact theory. The experimental results in the impact tests were compared with those in the quasi-static indentation tests. It was proved that the minimum and maximum radii of multiple ring cracks increased with increasing speed or maximum collision load, and that the corn crack growth also had the collision speed-dependency. The maximum radius of the ring crack agreed well with a theoretical one which was derived based on the Hertz's theory while the minimum radius of the ring crack becomes smaller than theoretical one at high collision speeds where the sphere was broken into pieces due to impact load. It was presumed from the analysis that a ring crack with a minimum radius was generated when the collision load reached 40% of the maximum one.