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Paper 64

Damping Optimization of Viscoelastic Laminated Sandwich Structures using the Direct Multisearch Method

J.F. Aguilar Madeira1,2, A.L. Araújo1, C.M. Mota Soares1 and C.A. Mota Soares1
1IDMEC/IST-Instituto Superior Técnico, Technical University of Lisbon, Portugal
2ISEL, Instituto Superior de Engenharia de Lisboa, Portugal

Keywords: multiobjective optimisation, direct multisearch, sandwich structures, damping.

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Sandwich plates with viscoelastic core are very effective in reducing and controlling the vibration response of lightweight and flexible structures, such as those frequently encountered in the aerospace industry, where the soft core is strongly deformed in shear, as a result of the adjacent stiff layers. The vibration damping of sandwich structures is determined by a large number of parameters which include material properties, thicknesses of both the constraining layers and the viscoelastic layer and fibre orientation of the face layer laminates [1].

A multiobjective approach for optimization of passive damping for vibration reduction in sandwich structures is presented in this paper. A layerwise finite element model for sandwich structures with viscoelastic core and anisotropic laminated face layers is used along with the complex modulus approach and the dynamic problem is solved in the frequency domain. Constrained optimization is conducted for maximisation of modal loss factors and minimisation of weight of sandwich plates with elastic laminated constraining layers and a viscoelastic core, with layer thickness and laminate layer ply orientation angles as design variables. The problem is for the first time solved using the direct multisearch solver (DMS) for derivative-free multiobjective optimization and solutions are compared with alternative ones obtained using genetic algorithms. DMS is a solver for multiobjective optimization problems which does not use any derivatives of the objective functions. It is based on a novel technique called direct multisearch, developed by extending direct search from single to multiobjective optimisation [2].

References

1
A. Araújo, P. Martins, C.M. Soares, C.M. Soares, J. Herskovits, "Damping optimization of viscoelastic laminated sandwich composite structures", Structural and Multidisciplinary Optimisation, 39, 569-579, 2009.
2
A.L. Custódio, J.F.A. Madeira, A.I.F. Vaz, L.N. Vicente, "Direct multisearch for multiobjective optimization", SIAM Journal of Optimization, 21, 1109-1140, 2011.