Experimental and numerical estimation of damping in composite plates with embedded viscoelastic treatments di Angelo De Fenza (Youcanprint)

Structures subjected to dynamic loads, generally show structural damping values wich are just slightly capable of reducing oscillations amplitude. In aerospace field, low structural damping, or high oscillations amplitudes, may impact negatively on structural stability and emitted noise. This is much evident if applied to structures in composite materials. In force of their stiffnessover- weight ratio, composite materials are deeply used in large assemblies and subassemblies belonging to fuselage and/or lifting surfaces (wing, tail empennages, control surfaces); on the other hand, structural advantages related to composite solutions are accompanied by drawbacks mainly due to materials’ high vibration and noise permeability.

By increasing structural damping it is possible to obtain a considerable noise and vibration reduction thus augmenting overall composite appeal in aerospace applications. Among the most common damping treatments in the aerospace field, viscoelastic materials embedding are widespread. This research activity was born in the wake of ARCA and COMFORT research projects, within which different types of composite material structures have been built. In particular, typical aircraft composite fuselage skin made by carbon fiber/epoxy resin pre-preg laminate treated with viscoelastic damping treatments have been utilized in this work. This research activity can be split up in two parts: the first one related to experimental tests; the second related to the numerical simulations.

About the experimental part, the objectives have been primarily the identification and validation of a procedure to extract the loss factor with a low dispersion of the data in different temperature conditions and, subsequently, to characterize the performance of two test panels in different environmental conditions like flight temperature conditions. About the numerical part, the objective has been the identification of a numerical procedure able to give as output the same result of the experimental tests, in terms of loss factor. In this direction, two ways have been undertaken by two different numerical approaches: explicit in time domain and direct in frequency domain.