The free vibration and damping characteristics of plates consisting of composite stiff-layers and an isotropic viscoelastic core were studied under thermal loads using finite element method. The temperature dependence of viscoelastic core properties and effects of pre-stresses are taken into account. The inherent composite damping and damping due to viscoelastic layer are compared. Parametric study is conducted with fiber angle, ply lay-up, and core thickness as parameters. The results show some interesting phenomenon like shifting of modes with temperature. © 2005 Elsevier Ltd. All rights reserved.

Pradeep Vangipuram

Natrajan Ganesan

Buckling

Damping

finite element method

Plates (structural components)

Sandwich structures

Thermal load

Viscoelasticity

Free vibration

Composite materials

Composite

FIBER REINFORCED COMPOSITE

finite element analysis

LOADING (TESTING)

Temperature

VIBRATION DAMPING

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Composite Structures

This paper presents numerical studies on the vibration and acoustic response characteristics of a fiber-reinforced composite plate in a thermal environment by considering the inherent material damping property of the composite material. Initially the critical buckling temperature is obtained, followed by free and forced vibration analyses considering the pre-stress due to the imposed thermal environment. The vibration response predicted is then used to compute the sound radiation. The critical buckling temperature and vibration response are obtained using the finite element method based on the Classical Laminate Plate Theory (CLPT) while sound radiation characteristics are obtained using a coupled FEM/BEM technique. It is found that the vibration response of the structure reduces with an increase in uniform temperature rise for both Glass Epoxy and PEEK/IM7 materials, but the overall sound radiation of the plate reduces only marginally due to interaction between reduced stiffness and enhanced damping. © 2008 Elsevier Ltd. All rights reserved.

Journal of Sound and Vibration

Vibration and acoustic response of a composite plate with inherent material damping in a thermal environment

This paper presents numerical simulation studies on the vibration and acoustic response characteristics of an isotropic rectangular plate in a thermal environment using commercial finite element softwares ANSYS and SYSNOISE. First the critical buckling temperature is obtained, followed by modal and harmonic analyses considering prestress due to the thermal field in the plate, with the critical buckling temperature as a parameter. The vibration response predicted is then used to compute the sound radiation. It is found that the displacement response of the structure increases with an increase in temperature for all boundary conditions. The overall sound radiation of the plate marginally increases with an increase in temperature for all boundary conditions when the temperature approaches the critical buckling temperature although there is a sharp increase in sound power levels. Copyright © 2008 by ASME.

Journal of Vibration and Acoustics, Transactions of the ASME

Vibration and acoustic response of an isotropic plate in a thermal environment

The paper deals with the vibration and thermal buckling behavior of sandwich beams with composite facings and viscoelastic core. Sandwich plate and beam elements are compared in this context. Each composite laminate is modeled as an equivalent single layer. Steady state temperature field is assumed. The formulation is a decoupled thermo mechanical formulation where in the temperatures in the domain of the beam are calculated first and made use in further calculations. The effect of fiber angle, the effect of aspect ratio and the effect of the core thickness on the performance of the elements is studied. The study reveals that there is a considerable difference between the predictions of plate and beam elements for some fiber angles. © 2006 Elsevier Ltd. All rights reserved.

Vibration and thermal buckling of composite sandwich beams with viscoelastic core

Composite sandwich structures have extensive applications due to their high strength and structural efficiency. Skew fibre-reinforced composite laminates are used as important structural elements in modern structural design, particularly in the aerospace industry. Natural frequency of these skew laminates is of primary significance to structural designers. The present article studies the free vibration and damping characteristics of sandwich skew plates consisting of composite stiff layers with viscoelastic (VEL) or electrorheological fluid (ER) core, using finite element method. The vibration behavior of these core materials is critically compared. Detailed analysis was conducted by varying the boundary conditions, core to stiff layer thickness ratios and stacking sequence. The inherent composite damping and the damping due to VEL (or ER fluid) core are investigated. The influence of electric field on the frequency and loss factor were also examined. © 2006 Elsevier Ltd. All rights reserved.

Critical comparison of viscoelastic damping and electrorheological fluid core damping in composite sandwich skew plates

The present work deals with the thermal buckling and vibration behavior of multi-layer rectangular viscoelastic sandwich plates. A decoupled thermo-mechanical analysis is made by using finite element method. An all side clamped (C-C-C-C) plate under thermal loads is analyzed for thermal buckling, frequency and damping behavior. The temperature-dependent characteristics of complex shear modulus of viscoelastic core are accounted. The formulation proposed by Kathua and Cheung [Bending and vibration of multi-layer sandwich beams and plates, International Journal for Numerical Methods in Engineering 6 (1973) 11-24] has been extended to study the thermal buckling and for predicting the critical buckling temperature of the multi-layer viscoelastic sandwich plates. The variation of natural frequency and loss factor with temperature has been studied. A parametric study is conducted to estimate the effect of core thickness and progressive sandwiching. Several interesting phenomenon like shifting of modes with temperature, decrease of membrane stiffness with the increase in core thickness and increase in level of sandwiching has been observed. © 2007 Elsevier Ltd. All rights reserved.

Thermal buckling and vibration behavior of multi-layer rectangular viscoelastic sandwich plates

Thermal buckling of angle-ply laminated composite and sandwich plates according to a global higher-order deformation theory

A higher order finite element theory for buckling and vibration analysis of initially stressed composite sandwich plates

Thermal buckling of cross-ply laminated composite and sandwich plates according to a global higher-order deformation theory

A simple C0 isoparametric finite element formulation based on a shear deformable model of higher-order theory using a higher-order facet shell element is presented for the free vibration analysis of isotropic, orthotropic and layered anisotropic composite and sandwich laminates. This theory incorporates a realistic non-linear variation of displacements through the shell thickness, and eliminates the use of shear correction coefficients. The validity and efficiency of the present formulation is established by obtaining solutions to a wide range of problems and comparing them with the available three-dimensional closed-form and finite element solutions. In addition, other plate and shell solutions of different kind and available in the literature are also compiled and tabulated for the sake of completeness. The parametric effects of degree of orthotropy, length-to-thickness ratio, plate aspect ratio, number of layers and fibre orientation upon the frequencies and mode shapes are discussed. © 2004 Elsevier Ltd. All rights reserved.

Fulltext

Free vibration of composite and sandwich laminates with a higher-order facet shell element

Buckling and vibration of rectangular composite viscoelastic sandwich plates under thermal loads

Journal	Composite Structures
ISSN	02638223
Open Access	No