Collisional Experiments of Gypsum Spheres at Low Velocities : Compactions and Restitution Coefficients of Simulated Porous Small Bodies

Abstract

Collision between solid bodies at low velocity regime is one of the most important elementary processes in the planetary formation or in the Saturn's ring particles collision.In our previous study, we performed low velocity collision experiments of gypsum spheres of about 50% in porosity.We found that compaction occurred at lower velocities than those where fragmentation fracturing occurred and the compaction reduced the value of restitution coefficient.We prepared gypsum spheres with porosity was higher than the previous ones in order to compare the degree of compaction and the effect of the porosity on the restitution coefficient.We quantitatively estimated the fraction of the energy partitioned to the compaction process, tangential velocity and rotational motion of the sphere after the impact and investigated the effects on the value of restitution coefficient.