The aim of this paper is to determine the optimum shape of a symmetric unconstrained viscoelastic damping layer for a laminated composite structure undergoing harmonic excitation. The objective is to minimize the peak displacement at the first damped natural frequency. The material loss factor is monitored to determine the improvement in performance. Beam and plate structures are examined for several boundary conditions. The common assumption of constant viscoelastic material properties is investigated by comparing optimization results for cases with constant properties to those with varying properties. ABAQUS finite element code is used to model the structures. The optimization code uses a Sequential Quadratic Programming algorithm. Results show dramatic improvement in the loss factor for optimized shapes. In addition, the use of frequency dependent viscoelastic properties is insignificant in the cases examined. Finally, results indicate that minimizing the displacement at one frequency may cause significantly worse performance at other frequencies.

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