Static and dynamic hygrothermal postbuckling analysis of sandwich cylindrical panels with an FG-CNTRC core surrounded by nonlinear viscoelastic foundations

In this article, analytical and semi-analytical methods are used to analyze the nonlinear static and dynamic hygrothermal postbuckling response of sandwich cylindrical panels with functionally graded carbon nanotube-reinforced composite (FG-CNTRC) core. The sandwich cylindrical panels with an FG-CNTRC core are resting on generalized nonlinear viscoelastic foundations which are consisted of a Winkler and Pasternak foundation parameters augmented by a Kelvin-Voigt viscoelastic model and a nonlinear cubic stiffness. The sandwich cylindrical panels with four types of FG-CNTRC core are considered such that the CNTs distribution types consist of the FG-O, FG-A, FG-X, and UD. Regarding to the classical shell theory and geometrical nonlinearity in von Karman-Donnell sense, the governing equation is obtained and discretized utilizing the Galerkin method. The nonlinear dynamic hygrothermal (NDHT) postbuckling is analyzed by means of the fourth-order Runge-Kutta method. The influences of material parameters, various geometrical characteristics, and nonlinear viscoelastic foundation parameters are studied on the nonlinear static hygrothermal (NSHT) postbuckling and NDHT postbuckling analysis of sandwich cylindrical panels with an FG-CNTRC core. The results show that the different types of CNTs distribution and nonlinear viscoelastic foundation parameters have a strong effect on the hygrothermal postbuckling behaviors of sandwich cylindrical panels with an FG-CNTRC core.