Nonlinear free vibration of functionally graded fiber-reinforced composite hexagon honeycomb sandwich cylindrical shells

In the present study, the nonlinear free vibration of functionally graded fiber-reinforced composite hexagon honeycomb sandwich cylindrical shells is investigated with consideration of the large-amplitude effect. First, an analytical model of such shell structures is proposed, which considers the functionally graded fiber-reinforced composite skins and a hexagon honeycomb core with their respective effective material properties being evaluated through the micromechanical model of Halpin-Tsai and the mixture law, as well as the modified Gibson's formula. Meanwhile, based on the first-order shear deformation theory and von K ' arm ' an geometrical nonlinear relations, the nonlinear partial differential governing equations are deduced via Hamilton's principle, which is further discretized into several ordinary differential equations by the Galerkin approach. Subsequently, the static condensation technique is adopted to decrease the degrees of freedom, and the frequency-amplitude relationships are obtained by the multiple scale expansion method. Following the validation of the developed model via comparing the predicted results to literature ones, a detailed parameter study of critical geometric and material parameters on the nonlinear vibration characteristics of the structure is conducted, with some important conclusions being provided to weaken the nonlinear hardening-spring behavior of the structure.

Automated summary

In this study, the nonlinear free vibration of functionally graded fiber-reinforced composite hexagon honeycomb sandwich cylindrical shells is investigated, taking into account the large-amplitude effect. An analytical model is proposed to describe the shell structures, and the governing equations are deduced based on the first-order shear deformation theory and von Kármán geometrical nonlinear relations. The frequency-amplitude relationships are obtained using the multiple scale expansion method. The study provides important conclusions on the nonlinear vibration characteristics of the structure through a parameter analysis.