Bending and instability behaviour of functionally graded cylindrical shells with porosities

This work examines the bending and instability behaviour of porous functionally graded unilamellar cylindrical shells and cylindrical sandwich shells with porous functionally graded core. For this purpose, isogeometric analysis (IGA) method capable of accomplishing easily the smoothness of higher-order continuity and of describing the complex shell geometries with high precision and cost-efficiency is taken advantage of. Quasi-3D (three-dimensional) trigonometric shear deformable shell theory with five unknowns suitable for the bending and instability analysis of thin and thick functionally graded cylindrical shells with porosities is established and utilized to formulate the equilibrium equations. The modified Newton–Raphson iterative technique combined with the arc length method is adopted to follow the entire equilibrium path of the porous functionally graded cylindrical shells in flexure. The proposed quasi-3D IGA approach, by testing the analysis capability through several benchmark problems, is confirmed to be accurate in predicting the flexural behaviour and in tracing the whole equilibrium path. Additional parameter study highlights impacts of the material gradient, porosity volume fraction, shell geometry, load type and constraint on the bending and instability responses. The new findings for the response behaviour of the porous functionally graded cylindrical shells in bending are regarded to be used as the future reference.