Buckling analyses of FG porous nanocomposite cylindrical shells with graphene platelet reinforcement subjected to uniform external lateral pressure

In this paper, buckling analyses of functionally graded porous nanocomposite cylindrical shells reinforced with graphene platelets (FGPNCS-R-GPLs) under uniform external lateral pressure are performed for the first time. FGPNCS-R-GPLs are built by infiltrating GPLs into the metal matrix containing open-cell internal pores. Hence, different GPLs and porosity distribution patterns called uniform and non-uniform are considered through the thickness of the shell. The modified Halpin-Tsai micromechanics model and the rule of mixtures are employed to estimate the effective modulus of elasticity and to compute density and Poisson's ratio of the porous nanocomposite shell respectively. The theoretical governing formulations are derived based the first-order shear deformation theory (FSDT), and then they are solved using Rayleigh-Ritz method to obtain the critical buckling pressure. Present formulations are validated by comparing the present numerical results with results obtained by finite element methods. Moreover, the effects of the number layer in the thickness direction, GPLs and porosity distribution patterns, porosity coefficient, GPL weight fraction, GPL shape, circumferential wave number, boundary condition and cylindrical shell dimensions are comprehensively investigated in detail to find the best parameter values to achieve the maximum buckling resistance of FGPNCS-R-GPLs.