Characterisation of viscoelastic layers in sandwich lightweight panels through inverse techniques

Constrained layer damping is a common way of passively reducing structural vibrations. To design such damping treatments, the frequency-dependent properties of the viscoelastic material are essential. Direct methods, such as dynamic mechanical analysis, may not be applicable to some polymers. The characterisation of viscoelastic materials through inverse approaches can overcome these limitations. The parameters of a viscoelastic model are identified by minimising residuals between experimental data and predictions from a finite element model. Though successfully applied to beam structures, this kind of approach has not been tested on more complex structures. In this work, the proposed inverse procedure, which identifies the parameters of a fractional derivative model over a large frequency band, is applied to frequency response functions measured on lightweight sandwich panels.