  We present an experimental and theoretical study of the shape of fragments
generated by explosive and impact loading of closed shells. Based on high speed
imaging, we have determined the fragmentation mechanism of shells. Experiments
have shown that the fragments vary from completely isotropic to highly
anisotropic elongated shapes, depending on the microscopic cracking mechanism
of the shell-material. Anisotropic fragments proved to have self-affine
character described by a scaling exponent. The distribution of fragment shapes
exhibits a power law decay. The robustness of the scaling laws is illustrated
by a stochastic hierarchical model of fragmentation. Our results provide a
possible improvement of the representation of fragment shapes in models of
space debris.
