Complex eigenfrequencies of constant-modulus/frequency-dependent viscoelastic soft core embedded sandwich composite curved panels

The present study examines the natural frequencies and corresponding modal loss factors of sandwich composites with viscoelastic cores defined using constant-modulus and frequency-dependent generalized Maxwell models. Here, sandwich panels with various curvature profiles such as flat, elliptical, spherical, cylindrical and hyperbolic are modelled. The frequency-dependent complex material properties of the soft viscoelastic core are adopted using elastic viscoelastic correspondence relations. Hamilton's principle is employed to obtain the governing equation via higher-order kinematics and a frequency-dependent constitutive model. The present viscoelastic core-based sandwich models are developed in a 2D Lagrange finite element platform to compute the natural frequencies and their corresponding modal loss factors. The present model is verified and validated by comparing with reported numerical and experimental models. A comprehensive numerical examination is executed to demonstrate the effect of the thickness of the viscoelastic soft core on the natural frequencies and their corresponding modal loss factors at different vibrational modes of sandwich configurations with different curvature profiles.