Free vibration characteristics of composite sandwich plates with embedded viscoelastic layers

Based on the first-order shear deformation theory, the vibration balance equation of composite sandwich plates with embedded viscoelastic layers (CSPEVL) is obtained by using Hamilton principle. The Navier closed-loop solution is used to solve the damping plate structure with four simply supported constraints. The correctness of the derived vibration balance equation is proved by comparing with the simulation results and reference. The verified equations are employed to analyze the dynamic characteristics of the CSPEVL. The results show that as the relative thickness of damping layer decreases, the first four order vibration frequencies of the whole structure all show a declining trend. However, the first four order loss factors are all distributed in an upward convex parabola. In addition, the damping performance of composite damping plate can be significantly enhanced by increasing the width/thickness ratio and aspect ratio of composite plate. More importantly, when the total thickness of the damping layer is constant, the symmetrical distribution of multilayer damping film greatly improves the dynamic performance of the composite structure. The work provides theoretical guidance for the dynamic optimization and structural design of damping sandwich composite structures.