  Experiments on crater formation in the strength regime were conducted using
projectiles of various shapes with an aspect ratio of ~1, including both solid
and hollow interiors. The surface diameter, inner (pit) diameter, and depth of
the craters on basalt and porous gypsum targets were measured. Using the bulk
density of the projectile, the surface diameter and depth for basalt and the
pit diameter and depth for porous gypsum were scaled using the pi-scaling law
for crater formation in the strength regime. The numerical code iSALE was used
to simulate the impact of projectiles of various shapes and interior structure
with similar bulk densities. Results show that the distributions of the maximum
(peak) pressure experienced and particle velocity in the targets were similar
regardless of projectile shape and interior structure, implying that the
dimensions of the final craters were almost identical. This is consistent with
the experimental results. Thus, we conclude that the size of the craters formed
by the impact of projectiles with different shape and interior structure can be
scaled using a conventional scaling law in the strength regime, using bulk
density as projectile density.
