A Continuum (filled polymer) is inhomogeneous and anisotropic. The Continuum is used in an injection moulding simulation at first (generally unnewton type of fluid). Then the continuum is solid (after cooling) and it is possible to carry out ordinary dynamics structural analysis with it. The solid continuum has different mechanical properties for each of discrete element. A consequent dynamics properties (natural frequencies) will generally have different values when influence of injection moulding is taken into account for analyses.