A finite element investigation of the post-buckling strength of thin-walled structural members under compression

By employing the finite element displacement method using the tangent stiffness approach, the paper presents results of post-buckling analysis of plates and three-dimensional thin-walled members subjected to uniaxial compressive loads. A simple rectangular element with six degrees of freedom at each node, suitable for the analysis of nonplanar prismatic members with slope discontinuities (folded plates), is employed. Both geometric and material nonlinearities have been considered based on a Lagrangian coordinate system and. the flow theory of plasticity. The nonlinear equations are solved using the Newton–Raphson method in the elastic range and the step-by-step method with equilibrium corrections in the plastic range. A modified Cholesky decomposition technique is employed to solve the basic stiffness equations.