FINITE ELEMENT MODELING OF COMPOSITE SANDWICHE PLATES WITH VISCOELASTIC LAYERS (original) (raw)
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VIBRATION ANALYSIS OF VISCOELASTICALLY DAMPED COMPOSITE SANDWICH PLATES
19th International Congress on Sound and Vibration 2012 (ICSV 19), 2012
A numerical method based on a finite element approach to analyze the vibration and acoustic response of composite sandwich plates is presented. This method is an extension of the finite element formulation developed for the study of sandwich composites beams damped by means of viscoelastic materials. It is based on a layerwise displacement field through the plate thickness. The formulation assumes the classical lamination theory for the composite faces and Mindlin's theory for the core. The governing equations, obtained from Hamilton's principle, are discretized using a triangular plate finite element. The proposed approach uses very few unknown variables, and in the context of multilayered sandwich structures, the total number of the unknown variables is independent of the number of layers, which leads to a total number of DOFs much lower than in most zigzag theories, where the number of DOFs increases proportionally to the total number of discrete layers. The accuracy of the presented model is demonstrated by comparing predictions of free and forced vibration analyses of various sandwich composite plates with the results obtained by the PATRAN/NASTRAN finite element software package using a 3-D layered model.
Finite Element Model for Damping Optimization of Viscoelastic Sandwich Plate Structures
Proceedings of the Thirteenth International Conference on Civil, Structural and Environmental Engineering Computing, 2011
In this work a simple and efficient finite element model is used for the damping optimization of multilayer sandwich plates, with a viscoelastic core sandwiched between elastic layers, including piezoelectric layers. The elastic layers are modeled using the classical plate theory and the core is modeled using Reddy's third-order shear deformation theory. The finite element formulation is obtained by assembly of N ''elements'' through the thickness, using specific assumptions on the displacement continuity at the interfaces between layers. The free vibration response of damped multilayer sandwich structures is characterized by solving an eigenvalue problem to obtain the fundamental natural frequency and corresponding modal loss factor. The optimization is conducted in order to maximize the fundamental modal loss factor, using gradient based algorithms, and afterwards, considering steady state harmonic motion the analysis is conducted in time domain to obtain the structure response. The model is applied in the solution of some illustrative examples and the results are presented and discussed.
Damping Evaluation of Conventional and Composite Plates using Different Structures-A Review
2016
Sandwich composites are widely used in aerospace and automobile structure and panels for their excellent stiffness at very low weight. Composite materials exhibit a wide range of mechanical properties and a complex structural behavior. As compared to conventional materials fiber reinforced polymer composites (FRP) has interesting properties such as light weight, high specific strength and stiffness which make it attractive for many engineering applications such as racing shells, automobile structures, body panel, aerospace manufacturing, snowboards, furniture etc. A new finite element model for laminated plate structures with viscoelastic core and laminated orthotropic layers has been formulated using a mixed layer wise approach. Damping is an important aspect related to behavior of composite structures. Damping results in dissipation of energy by a vibration system. The dynamic problem is solved in the frequency domain. In order to obtain a frequency response which includes viscoelastic damping properties, the study is based on Isotropic plates, Laminated sandwich plate, Stiffened sandwich plate and Honeycomb cored sandwich plate in the frequency domain. Three materials are compared for the core: Aluminium (Al), Mild Steel (MS) and Fiber Reinforced Plastic (FRP). For the honeycomb core sandwich plate frequency is being obtained and results compared with the results of different damping ratios. All the work is to be done in ANSYS Software and Experimental Validation with the Fast Fourier Transform.
A finite element analysis of viscoelastically damped sandwich plates
Journal of Sound and Vibration, 1992
A finite element analysis associated with an asymptotic solution method for the harmonic flexural vibration of viscoelastically damped unsymmetrical sandwich plates is given. The element formulation is based on generalization of the discrete Kirchhoff theory (DKT) element formulation. The results obtained with the first order approximation of the asymptotic solution presented here are the same as those obtained by means of the modal strain energy (MSE) method. By taking more terms of the asymptotic solution, with successive calculations and use of the Pad6 approximants method, accuracy can be improved. The finite element computation has been verified by comparison with an analytical exact solution for rectangular plates with simply supported edges. Results for the same plates with clamped edges are also presented.
Composite Structures, 2001
The dynamic behaviour of ®bre reinforced plastic sandwich plates with PVC foam core is investigated in this paper. Recently, the authors have developed an analytical method based on Reddy's re®ned high-order shear deformation theory to study the dynamic behaviour of undamped ®bre reinforced plastic (FRP) sandwich plates. The present paper explains how the dynamic constitutive material properties (obtained by carrying out DMTA tests) are introduced into the analytical model using the elastic±viscoelastic principle. The obtained equations of motion are used to carry out steady state analysis and to determine the natural frequencies and modal loss factors of speci®c composite sandwich plates.
Analysis of flexural vibration of viscoelastically damped sandwich plates
Journal of Sound and Vibration, 1988
The simplified governing equations and corresponding boundary conditions of flexural vibration of viscoelastically damped unsymmetrical sandwich plates are given. The asymptotic solution to the equations is then discussed. If only the first terms of the asymptotic solution of all variables are taken as an approximate solution, the result is identical with that obtained from the Modal Strain Energy (MSE) Method. As more terms of the asymptotic solution are taken, the successive calculations show improved accuracy. With the natural frequencies and the modal loss factors of a damped sandwich plate known, one can calculate the response of the plate to various loads providing a reliable basis for engineering design.
A finite element model for the analysis of viscoelastic sandwich structures
Computers & Structures, 2011
In this work a finite element model is developed for vibration analysis of active-passive damped multilayer sandwich plates, with a viscoelastic core sandwiched between elastic layers, including piezoelectric layers. The elastic layers are modelled using the classic plate theory and the core is modelled using the Reissener-Mindlin theory. The finite element is obtained by assembly of N ''elements'' through the thickness, using specific assumptions on the displacement continuity at the interfaces between layers. The lack of finite element plate-shell models to analyse structures with passive and active damping, is the principal motivation for the present development, where the solution of some illustrative examples and the results are presented and discussed.
Damping analysis of an advanced sandwich composite structure
2006
The aim of the paper is to determine the most important features of damping in the case of an advanced sandwich composite structure starting from the dampings, dynamic Young moduli and Poisson ratio for every lamina. The structure features two carbon/epoxy skins reinforced with a twill weave fabric and an expanded polystyrene (EPS) core. At the damping analysis of fiber
Finite Element Vibration Analysis of Damped Composite Sandwich Beams
The International Journal of Acoustics and Vibration
In this study, a finite element model for the vibration analysis of cross-ply laminated sandwich beams is presented. This formulation is an extension of our previous work on predicting the acoustic and vibration responses of sandwich beams and plates with homogeneous elastic faces and a viscoelastic core. The formulation is based on a layerwise linear axial displacement through the beam thickness. The formulation assumes the classical lamination theory for the faces and Timoshenko theory for the core. The governing equations of motion are obtained using Hamilton's principle. A finite element method and a beam element are further developed to predict the natural frequencies and modal loss factors. In order to validate the proposed model, several free vibration analyses of composite sandwich beams with different boundary conditions, length-to-thickness ratios and face laminations are presented. The results are then compared with solutions available in the literature and with those obtained by the PATRAN/NASTRAN finite element software package. These results show the validity of the present formulation. Finally, the effects of ply-stacking sequence, core-to-face stiffness ratio and core-to-face thickness ratio upon the natural frequencies and modal damping are investigated.