Experimental identification of equivalent viscoelastic models for vibrating plates.

Aim of the present study is the identification of equivalent viscoelastic models for layered plates, obtained from vibration measurements only, able to fit the experimental data on relatively broad frequency ranges by means of a minimum number of parameters. A novel approach is proposed, based on a definition of an equivalent modal damping ratio applied to the circle-fit technique, to overcome the difficulties related to the identification of modal parameters when adopting non-conventional viscoelastic models. If the structural internal dissipative effects are dominant, this procedure identifies the parameters of an equivalent Young’s modulus in the frequency domain, representing the viscoelastic properties of a homogenized structure as a scalar function with frequency-dependent real and imaginary parts. The proposed procedure is applied to the analysis of Aluminum plates coated by damping pads and of plates made by Quiet Aluminum. To fit the experimentally found equivalent modal damping ratios, the linear Fractional Kelvin-Voigt viscoelastic model is adopted, assessing the accuracy of the identified parameters by comparison of numerically simulated with experimentally measured frequency response functions.