Experimental identification of viscoelastic properties of vibrating plates

Aim of the present study is the identification of equivalent viscoelastic models for layered thin walled structures, obtained from vibration measurement only, able to fit the experimental data on a wide frequency range by means of a minimum number of parameters. An identification method of general validity is proposed, based on the concept of equivalent modal damping ratio and on the classical circle-fit technique. It is applied to the analysis of both Aluminum plates coated by damping pads and plates made by Quiet Aluminum. To fit the experimentally found equivalent modal damping ratios, the linear Fractional Kelvin viscoelastic model is adopted, assessing the accuracy of the identified parameters by comparison of numerically simulated with experimentally measured frequency response functions.