Numerical and experimental studies for the impact of projectiles on granular materials

Abstract

Over the last decades, a lot of attention has been given to the quasi-static behavior of the granular materials. Also, impact problems become important in the field of material engineering and soil mechanics: for example the penetration into the surface of planet by meteorites or projectiles like Nereus Sample Return Project by the Institute of Space and Astronautical Science (ISAS) in Japan. However, only a few attempts have so far been made at impact dynamics of granular materials and shock waves in granular materials and granular layers. The impact behavior of granular materials is quite different from that of other continuous solid materials because of the compressibility and fluidity of granular materials. In this chapter, the dynamic response of granular materials to impact of a spherical projectile is investigated experimentally and also numerically using discrete element method. The two-dimensional granular material comprised of nylon spheres arranged regularly in a rectangular container is collided by a steel sphere at velocities less than 15m/s. The numerical simulations are compared with the measurements using high-speed video camera. The motion of each particle can be traced in detail by discrete element method. Also, it becomes clear that the walls of the container have a significant effect on the impact behavior of granular materials.