Effects of warhead shape on hypervelocity impact of a rod-shaped projectile onto a thin plate

When a projectile impacts a thin plate at hypervelocity, the projectile material usually undergoes deformation, fragmentation, and even phase transition under the action of a complex wave system, forming a secondary debris cloud. It has been shown that the head shape of the rod affects the hypervelocity impact between the rod and a thin plate. A series of SPH (smoothed particle hydrodynamics) numerical simulations of the hypervelocity impact by rods with flat head, hemispherical head, and cone head at impact velocities of 3.30 km/s and 6.0 km/s and length-to-diameter ratios of 2/1 and 3/1 were carried out. Simulation results show that the intensity of the shock wave and the failure in the material are affected by the head shape of the rod. With the impact across the plate, the mass loss and kinetic energy loss of the rod are related to the head shape. Obtuse cone head and flat head impact produce the strongest shock wave, most intense projectile fragmentation, and largest loss of rod mass and kinetic energy. A model of the interaction between the rod and the plate, as well as the shock wave generation during the impact, was built. The model shows that there exists a critical half-cone angle (related to the impact velocity and the target material), which leads to continuous interaction between rod and plate and makes the fragmentation of the rod projectile the most violent. For the hypervelocity impact of projectiles with different shapes, in a previous work, the impact-induced shock wave in a cone is more severe than that of a sphere or a rod, while another work has an inconsistent result. The model was successfully used to explain the contradictory results. This paper can provide some references for the research of hypervelocity impact and the protection design of space debris.