Estimation of Foreign-object Damage to Silicon Carbide Plates by Silicon Nitride Spherical Projectiles

This study experimentally and numerically investigated the damage extension of a brittle monolithic silicon carbide plate in response to the high speed impact of a projectile. An out-of-plane impact of a silicon nitride sphere with a velocity of 50 to 600 m/s induced multiple ring cracks on the contact surface. A crater, a cone crack, and a median crack were observed in the cross section under the contact point. The generation and extension of the damage were numerically studied based on linear fracture mechanics. A dynamic stress analysis using the finite element method demonstrated that the distribution of the principal axis corresponding to the maximum principal stress aligned radically from the contact point to induce a circular crack on the surface.