ON COLLISIONAL DISRUPTION - EXPERIMENTAL RESULTS AND SCALING LAWS

We present results from an experimental program designed to measure impact strengths, fragment sizes, and fragment velocities resulting from the collisional shattering of cement mortar targets having crushing strengths which vary by an order of magnitude. Both homogeneous and nonhomogeneous targets, together with a variety of projectile types, are used in 116 shots covering a velocity range from 50 to 5700 m/sec. The impact strengths of strong and weak homogeneous mortar targets are found to be nearly identical, contrary to what would be expected from their static strengths. However, combining our data with other published results shows that the dynamic impact strength is correlated with quasi-static material strengths for most materials ranging from basalt to ice. Two materials that do not follow this trend are the weak mortar used in this program and the clay targets used by A. Fujiwara and N. Asada (1983, Icarus 56, 590-602). A simple scaling algorithm based on impact energy, material properties, and collisional strain rate is shown to predict values which are consistent with experimental results for the size of the largest collisional fragment. Data on fragment velocities are given for 30 of our collisional experiments, and we find a shallower exponent for the mass-velocity distribution resulting from catastrophic collisions as compared with cratering impacts into sand. © 1990.