Experimental Identification of Viscoelastic Properties of Plates Made of Quiet Aluminum

The present study is aimed at the identification of equivalent viscoelastic models for layered thin-walled structures, obtained from vibration measurement only. Accurate modeling of modal properties is fundamental for describing metal fatigue, caused by forced vibration on structural components. A new 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. When the structural internal dissipative effects are dominant, this procedure identifies the parameters of an equivalent Young’s modulus in the frequency domain. The proposed procedure is applied to the analysis of plates made by quiet aluminum, adopting the linear fractional Kelvin-Voigt viscoelastic model and assessing the accuracy of the identified parameters by comparison of numerically simulated with experimentally measured frequency response functions.