Dynamics Analysis of Viscoelastic Sandwiched Structures Integrated with Aluminum Sheets by Using Finite Element Method

Passive vibration attenuation of modern mechanical structures is one of the most essential technologies applied to the arsenal of modern mechanical structures. In this thesis, dynamics analysis is performed on viscoelastic (VE) beam and plate sandwich structures. The proposed structures are composed of a VE core and aluminum face sheets as the substrate layers on both sides of the structure. The small-strain VE material is modeled based on the complex constant moduli model. In the modal analysis, the model effective mass analysis is performed to investigate its dominant mode shape and its sweet spot at resonance. Then, in the harmonic analysis, the resonance frequency is obtained to evaluate the performance of the VE sandwich structures via the maximum deformation. A comparison between the results of an analysis of viscoelastic sandwiched structures with subsequent done using FE models. A numerical application is accomplished to develop the integral shear finite element and modal assembly of the stiffness element and mass element established according to strain energy and the Hamilton principle. The harmonic analysis is done using ABAQUS® software with both C3D20RH®, CPS8R where C3D20RH indicates a 3- D element with 20 nodes with reduced integration technique and hybrid formulation and CPS8R indicates 2-D plane strain with eight nodes with reduced integration technique, the results are compared against analytical solutions form the literature, a parametric study is done on the beam’s core thickness to study the effect on the damping characteristics of the beam, the results showed that the modal developed in MATLAB® achieved the least error compared to the analytical solution from the literature and then comes the Abaqus® software solution, also the parametric study showed that the natural frequency of the beam does not change with the increase of the core thickness, however, the loss factor is directly proportional to the thickness of the viscoelastic layer of the beam. Keywords: Viscoelastic, Sandwich Beam/Plate, Dynamics Analysis, Complex Constant Moduli, Finite Element Method, Shear Deformation Theory