Buckling and postbuckling of porous cylindrical shells with functionally graded composite coating under torsion in thermal environment

This paper investigates the nonlinear buckling and postbuckling of functionally graded porous circular cylindrical shells reinforced by orthogonal stiffeners resting on Pasternak elastic foundations in thermal environment and under torsional load by an analytical approach. Shells are reinforced by closely spaced stringers and rings in which material properties of the shell and the stiffeners are assumed to be continuously graded in the thickness direction. Basing on the classical shell theory with von Karman geometrical nonlinearity and smeared stiffeners technique, the governing equations are derived. Using the Galerkin method with the three-term solution of deflection, the closed form to find critical load and post-buckling response are obtained. The effects of porosity coefficient, material, temperature, dimensional parameters, stiffener and foundation are analyzed.