  Finite element analysis has been used successfully to estimate the effective
properties of many types of composites. The prediction of effective elastic
moduli of polymer-bonded explosives provides a new challenge. These particulate
composites contain extremely high volume fractions of explosive particles ($>$
0.90). At room temperature and higher, the Young's modulus of the particles can
be 20,000 times that of the binder. Under these conditions, rigorous bounds and
analytical approximations for effective elastic properties predict values that
are orders of magnitude different from the experimental values. In this work,
an approach is presented that can be used to predict three-dimensional
effective elastic moduli from two-dimensional finite element simulations. The
approach is validated by comparison with differential effective medium
estimates and three-dimensional finite element simulations.
