Head-shape effects on the hypervelocity impact between a rod onto a thin plate

When a projectile impacts a thin plate at hypervelocity, the projectile material usually undergoes deformation, fragmentation, or even phase transition phenomenon under the action of complex wave system, forming a secondary debris cloud. For rod-shaped projectiles, it has been shown that their aspect ratio is an important factor affecting the fragmentation of rod-shaped projectiles. In this paper, a series of SPH numerical simulations of impacts by the rods with flat head, hemispherical head and cone head are carried out. The results show that, in terms of different head shapes, large obtuse cone head and flat head impact with thin plate produce the strongest shock wave, more intense projectile fragmentation, larger projectile kinetic energy loss. Combined with the analysis of the shock wave during the impact, the phenomenon is qualitatively explained. At the same time, it is predicted that for the cone head, there exists a critical half-cone angle (related to the impact velocity and the target material), which makes the fragmentation of the rod projectile the most violent. The prediction is in line with the existing simulation results. This paper can provide some theoretical references for hypervelocity collision related research such as protection design of non-spherical space debris.