Nonlinear torsional buckling of functionally graded graphene‐reinforced composite (FG‐GRC) laminated cylindrical shells stiffened by FG‐GRC laminated stiffeners in thermal environment

The main aim of this article is to establish an analytical approach on the torsional postbuckling for functionally graded graphene‐reinforced composite (FG‐GRC) laminated circular cylindrical shells stiffened by FG‐GRC laminated stiffener system in thermal environment and subjected to torsion loads. The polymer matrixes of shell skin and stiffeners are reinforced by graphene with two graphene reinforcement directions, namely, zigzag and armchair directions. The anisotropic smeared stiffener technique for FG‐GRC stiffener system is used, and the governing equations are established based on the Donnell shell theory with von Kármán–Donnell‐type geometrical nonlinearity and the Airy's stress function. A three‐state solution of deflection is chosen and Galerkin's method is applied, the explicit forms of critical buckling torsion and expression of load‐deflection postbuckling curves relation are obtained. The effects of graphene‐reinforced composite laminated stiffeners, uniformly distributed temperature, the volume fraction of graphene of stiffened shell on the nonlinear torsional buckling behavior are numerically investigated.