Análise de vibração em estruturas sanduíche com materiais compósitos e núcleo viscoelástico utilizando o método da transformada diferencial

Abstract

In this thesis a dynamic analysis is made through the solution of the differential equation of motion of a composite beam model composed of three layers, two with composite material and one with a viscoelastic core. Initially, the differential equation that governs the free vibration movement is obtained through the composite beam theory applying Hamilton’s Principle. This equation is solved using the Differential Transform Method. Modal parameters such as natural frequencies and vibration modes are obtained. We describe step by step the development of specimens made with fiberglass material and epoxy resin, where the viscoelastic layer is embedded together between the layers of the fiberglass mat in the vacuum infusion process known as VARTM. The damping factors for composite beams with viscoelastic core are determined, using the velocity response in time of the free vibration test, using for this the representation of a system with one degree of freedom. Finally, the numerical results obtained are compared with other authors, theoretical and experimental results, in order to analyze the effectiveness of the theoretical equation and the solution method used. A good agreement between theoretical and experimental results is observed.