Abstract <p>The present study is an in-depth theoretical investigation into the influence of fullerenes on the characteristics of Al/C₆₀ composite materials. The paper sets out to explore the dependences of density and stiffness constants on the concentration of inclusions, as well as the bulk and shear moduli for isotropic polycrystalline nanocomposites calculated using the molecular dynamics (MD) method. The analysis demonstrates that the interfacial interaction significantly affects the properties of nanocomposites. The interfacial layer model within the framework of composite materials theory provides a means to account for this effect. The properties of the interfacial layer are determined by the interfacial interaction and can be calculated by approximating the results of calculations employing the MD method. Assumptions about the simplified form of the two-particle distribution function allow for the calculation of the interfacial interaction energy and interfacial layer properties analytically. The numerical results and analytical estimates are compared and the validity of the approximations used is discussed. The analysis performed on the example of Al/C₆₀ composite material has shown the expediency of using the analytical model of the interfacial layer to estimate the effective density and elastic moduli of materials with nanoscale inhomogeneities.</p>