Keywords: sandwich beams, composite laminates, finite element modelling, core compressibility.

This paper presents a new sandwich plate finite element model with transverse compressibility of the core, which is an important feature for soft core sandwich structures [1]. The element is formulated for dynamic analysis of sandwich plates with viscoelastic core and composite laminated face layers. A layerwise approach is used, where the high shear deformations inside the core are modelled using a higher order deformation theory, allowing for transverse normal stress and strain. The face layers of the sandwich are modelled using a first order shear deformation theory. This element is a generalisation for passive damping of the one developed by Araújo et al. [2] for transversely incompressible cores.

Damping is included for the core material using the elastic-viscoelastic correspondence principle, through the complex modulus approach, which can incorporate frequency dependent properties.

In the paper, the element is validated against solutions found in the literature for soft core sandwich plates and beams. Natural frequencies are compared for both bending and thickness-stretch modes and the agreement is found to be rather good. Modal loss factors are also calculated for a beam with soft damped core and it is evident that the thickness-stretch modes are in general more heavily damped than the bending ones.

1

Y. Frostig, M. Baruch, "Free vibration of sandwich beams with a transversely flexible core: a higher order approach", Journal of Sound and Vibration, 176, 195-208, 1994.

2

A.L. Araújo, C.M. Mota Soares, C.A. Mota Soares, "Finite element model for hybrid active-passive damping analysis of anisotropic laminated sandwich structures", Journal of Sandwich Structures and Materials, 12, 397-419, 2010. doi:10.1177/1099636209104534

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