Torsional buckling analyses of functionally graded porous nanocomposite cylindrical shells reinforced with graphene platelets (GPLs)

Due to superior characteristics added to composite structures by using graphene-platelets (GPLs) as nanofillers, this article investigates torsional buckling analysis of functionally graded graphene-platelets reinforced composite (FG-GPLRC) porous cylindrical shell within the framework of the first-order shear deformation theory (FSDT). The relationship between coefficients of porosity and mass density is determined based on the typical mechanical property of an open-cell metal foam. The modified Halpin-Tsai micromechanics model is employed to estimate the effective modulus of elasticity and the rule of mixtures to compute density and Poisson's ratio of the shell material. First-order shear deformation theory and Rayleigh-Ritz method are employed to establish the related eigenvalue equations in order to calculate the critical buckling torque. The accuracy of the applied approach is examined by comparing the numerical results with those published in the available literature and also with the simulation results of ABAQUS. Additionally, the effects of various matrix materials, internal porosities and GPLs distribution patterns, size and concentration of porosities, GPLs weight fraction, graphene plates dimensional ratios, geometric factors such as mid-radius to thickness ratio and length to mid-radius on the torsional performance of FG-GPLRC porous cylindrical shell are inspected. The results of this article can be regarded as practical designing hints for engineers analyzing the mechanical behavior of innovative composite structures.