Impact Crater Formation at Intermediate Velocities

Abstract

The influence of projectile strength on cratering was investigated for projectiles of aluminum alloys impacting semi-infinite aluminum targets over the velocity range of 1 km/sec to 5.0 km/sec. The experimental results showed that crater diameters were not significantly influenced by varying projectile strength. The crater depths were found to vary appreciably with strength at lower velocities but to become virtually the same at 3.5 km/sec for the series of projectile alloys investigated. A simple dynamic model for cratering was developed and compared with the experimental results of this study and other experimental results at higher velocities. These comparisons showed that the model provided predictions of crater diameter which were within 8 percent for the experimental results of this study and within 13 percent for the hypervelocity data. Crater depth predictions showed good agreement with the experimental results of this study for projectiles having greater yield strength than the target material. The predictions of depth as a function of velocity showed qualitative agreement with the hypervelocity data.

On the Fluidic Response of Structures in Hypervelocity Impacts

“…The water sphere and "plate" were modeled using quarter symmetry and a total of 370,000 particles. The aforementioned fluid material model was applied with a density of 1 g/cm 3 , and viscosity was varied from the 0.001 PaÁs of water up to 100 PaÁs. Parameters for the shock behavior were taken from Liu and Liu [16] for the water baseline, and were similarly used for all viscous models.…”

“…Due to the immense kinetic energy of particles traveling in the hypervelocity regime, inertial effects dominate the onset of damaging effects and many materials behave fluidically [3]. However, stiffness and shear effects can contribute to projectile resistance and evolution of the debris cloud in non-negligible magnitudes.…”