A Study of Mass Loss at Hypervelocity Impacts of Projectiles with Single- and Multilayer Targets

A hypervelocity impact is an impact event where the relative velocity (V) between two colliding objects is close to or exceeds the speed of sound (C0) in each of the object’s materials (usually V > 4 [km/s]). During such an impact, a large amount of kinetic energy is released within a very short time, and supersonic compression shock waves are formed at the contact surface between the colliding objects. They propagate through the objects and are followed by a relief wave (expansion wave). These shock waves form zones of high temperature and pressure (and consequently their high gradients), where strong strains, material deformation, and, in most hypervelocity impacts, destruction of large parts of the object materials are observed. These effects propagate much deeper and farther from the collision point (in comparison to the characteristic size of the hitting projectile). Figure 1 illustrates a calculation [1] of a typical collision of an aluminum projectile (diameter d ) with an aluminum target (thickness t s >> d, i.e., half-infinite target) at different times t after impact.