  The paper analyzes theoretically the influence of fullerenes on the
characteristics of $\mathrm{Al/C}_{60}$ composites. The molecular dynamics
method is used to study the dependences of density and stiffness constants on
the concentration of inclusions, and to calculate the values of the bulk and
shear moduli for isotropic polycrystalline nanocomposites. The analysis shows
that interfacial interaction significantly affects the properties of
nanocomposites. This effect can be taken into account within the framework of
the theory of heterogeneous media using the interphase layer model. The
properties of the interphase layer are determined by interfacial interaction
and can be calculated by approximating the results of molecular dynamics
calculations. Using assumptions about the simplified form of the two-particle
distribution function allows the interfacial interaction energy to be
calculated and the interphase layer properties to be assessed analytically. The
paper compares numerical results and analytical estimates, and discusses the
validity of the approximations used. The analysis performed on the example of
an $\mathrm{Al/C}_{60}$ composite material demonstrates the feasibility of
using the analytical model of the interphase layer to estimate the effective
density and elastic moduli of heterogeneous media with nano-inhomogeneities.
