has developed around the conical damage region. Later on these cracks run together to form few oblique cracks (see Fig. \[snapshots\]c) directing radially outward. As crack propagation is very energy dissipative, when these oblique cracks move outwards, the intensity of the compressive wave gradually decreases and hence larger fragments appear opposite the impact point.

To demonstrate the effect of the impact velocity on the break-up process, in Fig. \[snapshot\] final states of the process are shown obtained at different impact velocities, with the fragments reassembled into the initial disc. At low velocities the compressive wave intensity generated at the impact point is low, and hence, the cone could not develop fully. Moreover, only a few oblique cracks are obtained, and they do not reach the opposite surface of the disc (Fig. \[snapshot\]a). As the velocity increases, more oblique cracks develop and cover a greater distance (Fig. \[snapshot\]b) and a considerable part of the initial kinetic energy goes into the motion of the residue resulting in rebound. At the impact velocity where the oblique cracks reach the outer surface of the disc opposite to the impact point, the break-up process drastically changes: below this velocity mostly contact damage occurs in the 