Buckling analysis of functionally graded material circular hollow cylinders under combined axial compression and external pressure

The unified formulations of finite cylindrical layer methods (FCLMs) based on the Reissner mixed variational theorem (RMVT) and the principle of virtual displacements (PVD) are developed for the three-dimensional (3D) linear buckling analysis of simply-supported, multilayered functionally graded material (FGM) circular hollow cylinders and laminated composite ones under combined axial compression and external pressure. In this work, the material properties of the FGM layer are assumed to obey the power-law distributions of the volume fraction of the constituents through the thickness coordinate, and full kinematic nonlinearity is also considered. The accuracy and convergence of the RMVT- and PVD-based FCLMs are assessed by comparing their solutions with both the exact 3D and accurate two-dimensional (2D) solutions available in the literature. A parametric study for variations of the lowest critical load parameters with the material-property gradient index, the load intensity, and the orthotropic, length-to-radius, and radius-to-thickness ratios is carried out.