We present a model of solids made from polygonal cells connected via beams.
We calculate the macroscopic elastic moduli from the beam and cell parameters.
This modellisation is particularly suited for the simulation of fragmentation
processes. We study the effects of an explosion inside a circular disk and the
impact of a projectile and obtain the fragment size distribution. We find that
if breaking only happens under tensile forces a layer on the free wall opposed
to impact is first ejected. In that case the distribution follows a power-law
with an exponent that in most cases is around two.Comment: 16 pages in LaTex format, 17 PostScript figures. Figures are
available upon request from the authors. Submitted to Int. J. of Mod. Phys.