Nonlinear vibrations of all-composite sandwich plates with a hexagon honeycomb core: Theoretical and experimental investigations

In this paper, the nonlinear vibration characteristics of an all-composite sandwich (ACS) plate with a hexagon honeycomb core (HHC) are investigated. Based on vibration tests on the HHC-ACS plate specimens, the amplitude-dependent vibration phenomenon owing to the material nonlinearity of the honeycomb core is recorded, whereby it is observed that the natural frequencies with different mode orders display an inversed downward trend with increasing the excitation amplitude of the base vibration. By introducing the amplitude-dependent fitting coefficients, the modified equivalent elastic moduli of HHC are assumed, thus facilitating the development of a nonlinear theoretical model. This model is based on Reddy's third-order shear deformation theory, together with Hamilton's principle and the four-node plate element method. After the amplitude-dependent natural frequencies and vibration responses are successfully solved, the calculated results are verified against the measured results through detailed comparisons. Using the validated model, the effects of material and geometric parameters of HHC on the amplitude-dependent vibration behavior are investigated, with some important conclusions being summarized to improve the anti-vibration capability. This research provides an effective model for analyzing the amplitude-dependent vibrations of the HHC-ACS plates, which can be easily extended to other types of composite sandwich plates.