Instability of Porous FGM Rectangular Hollow Section (RHS) Beam Element in a Thermal Environment

This work aims to examine the stability of rectangular hollow section (RHS) beams with functionally graded (FG) thin walls that are subjected to thermo-mechanical loads and different boundary conditions. A nonlinear analytical model for predicting thermal buckling that introduces distortional deformation and takes porosity into account is presented. Using Ritz’s method, coupled nonlinear equilibrium equations are established and then the tangential matrix is formed to obtain critical values. Material properties vary continuously and progressively across the thickness according to a power law of the porous volume fraction and are assumed to be unrelated to the temperature. A finite element (FE) simulation using the FE ABAQUS software is employed to verify the applicability of the current model in predicting lateral torsional buckling (LTB) resistance. Several numerical examples are used to illustrate the impacts of temperature, porosity, power-law index, and axial loads on the instabilities of FG box beams.