A nonlinear model-based parametric procedure, aimed at estimating the material complex elastic E(ω) tensile modulus and the G(ω) shear modulus from forced flexural vibration measurements on some beam specimens, made of the same material but different geometry, is proposed. The analytical frequency transfer function, related to the specimen response and excitation in the same experimental degree of freedom, is found. An algebraic, iterative E(ω) and G(ω) material parametric identification procedure is obtained. To filter the contribution of the experimental noise, E(ω) and G(ω) discrete values obtained by means of the identification procedure are fitted by means of B-spline functions. The identification of a known material model from numerically simulated data with added random noise is reported, and some results concerning the experimental identification of the unknown model of some materials are also reported.