Hypervelocity impacts of polymer spheres on graphite: Experiments and simulations

Space debris is a major concern for aerospace industry, which has to design structures able to withstand hypervelocity impacts of small projectiles at several kilometers per second. To study this phenomenon, a series of nine shots has been performed on a two-stage gas gun at velocities ranging from 2100 m.s⁻¹ to 6300 m.s−¹. Projectiles were 2 mm diameter spheres made of Delrin, a polymer of density 1425 kg.m−³. Targets were 15 mm thick and made of EDM3, a porous and homogeneous graphite of density 1754 kg.m−³. After each shot, the generated crater has been measured using an optical profilometer. Experimental setup and results are detailed in this paper. Especially, the evolution of crater dimensions as a function of projectile velocity is shown and a scaling is proposed to compare these data to others obtained with aluminum projectiles on the same facility. Furthermore, some 2D-axisymetrical Eulerian simulations have been performed with the Hesione hydrocode developed at CEA. Our modeling of EDM3 and Delrin reproduced the nine experiments with satisfactory agreement.