Three-dimensional beam element for pre- and post-buckling analysis of thin-walled beams in multibody systems

Abstract This paper presents a three-dimensional beam element for stability analysis of elastic thin-walled open-section beams in multibody systems. The model is based on the generalized strain formulation. In this formulation, set independent deformation modes defined which are related to dual stress resultants co-rotational frame. characterized by strains or deformations, expressed as analytical functions nodal coordinates referred global coordinate system. A nonlinear theory non-uniform torsion adopted derivation and geometric stiffness matrices. Both torsional-related warping Wagner’s stiffening torques taken into account. Second order approximations axial elongation bending curvatures included additional second terms expressions deformations. allows study buckling post-buckling behaviour asymmetric with open cross-section that can undergo moderately large twist rotations. inertia properties described using both consistent lumped mass formulations. latter used rotary inertias cross-section. Some validation examples illustrate accuracy computational efficiency new under various loads (quasi)static boundary conditions. Finally, applications problems presented, including an elementary two-flexure cross-hinge mechanism.