Assessment of natural frequencies and modal loss factors of multi-layered hybrid sandwich composites with frequency-dependent viscoelastic damped polymer core

The present study focuses on the multi-layered sandwich composite panel with a viscoelastic damped polymer core to examine the natural frequencies and their corresponding mode shapes and modal loss factors. Here, three-layered and five-layered sandwich structures are configured with face-sheets, core and intermediate layers. The viscoelastic damped polymer core is defined using the elastic-viscoelastic correspondence model, which enables frequency-dependent material nonlinearity. The sandwich structure’s kinematics is based on the higher-order equivalent single-layer theory. In the present eigenvalue problem comprising a complex stiffness term, the governing equations are obtained using Hamilton’s principle and further solved in a 2D finite element framework via Lagrange elements. The mesh-refinement, followed by verification tests are performed to confirm the accuracy of the present solution. A comprehensive numerical investigation is conducted to demonstrate the impact of geometrical/material/boundary parameters of multi-layered hybrid sandwich panel with soft core on the natural frequencies and their corresponding modal loss factors. The obtained results will help study the dynamic behavior of sandwich composite structures embedded with soft cores.