Experimental model identification and validation of standard and functionally graded materials for aerospace, automotive and high speed industrial applications

The constitutive equivalent material models of specimens prepared with standard viscoelastic materials and Functionally Graded Materials (FGM) are identified and optimized by means of a robust identification technique. The constitutive relationship is modelled by means of a generalized Kelvin model and expressed in the form of the ratio of two frequency dependent polynomials. The polynomial parameters are identified by means of a least square error formulation adopting Forsythe orthogonal polynomials. The model non-physical components are eliminated in order to obtain a reduced and optimized model. The procedure is applied on force and displacement data obtained by means of dynamic mechanical measurement tests on standard viscoelastic specimens and composite FGM specimens. Various types of FGM specimens are prepared by producing dual-layer coatings of Ti and TiO2 and single-layer coatings of Al2O3 on different substrate materials and the results are compared and discussed.